volume 12 of _Nietzsche's Works_, edit. Naumann-Kröner, Leipzig, 1886.)
In this strange association of inorganic salts with human temperaments, the role of iron phosphate as a producer of courage is particularly interesting. What would a modern philosopher conclude if he followed the development of insight into the composition and function of complex phosphate compounds in organisms?
From Inorganic to Organic Phosphates
By the middle of the 19th century, the source of phosphorus in natural phosphates and the chemistry of its oxidation products had been established. The main difficulty that had to be overcome was that these oxidation products existed in so many forms, not only several stages of oxidation, but, in addition, aggregations and condensations of the phosphoric acids. Once the fundamental chemistry of these acids was elucidated, the attention of chemists and physiologists turned to the task of finding the actual state in which phosphorus compounds were present in the organisms. It had been a great advance when it had been shown that plants need phosphates in their soil. This led to the next question concerning the materials in the body of the plant for which phosphates were being used and into which they were incorporated. Similarly, the knowledge that animals attain their phosphates from the digested plant food called, in the next step of scientific inquiry, for information on the nature of phosphates produced from this source.
The method used in this inquiry was to subject anatomically separated parts of the organisms to chemical separations. The means for such separations had to be more gentle than the strong heat and destructive chemicals that had been considered adequate up to then. The interpretation of the new results naturally relied on the general advance of chemistry, the development of new methods for isolating substances of little stability, of new concepts concerning the arrangements of atoms in the molecules, and of new apparatus to measure their rates of change.
In the system of chemistry, as it developed in the first half of the 19th century, the new development can be characterized as the turn from inorganic to organic phosphates, from the substance of minerals and strong chemical interactions to the components in which phosphate groups remained combined with carbon-containing substances.
Phosphatides and Phosphagens
The important phosphorus compounds in organisms are much more complex than the simple salts, to which Nietzsche attributed such influence on man's character. Long before he wrote, it was known that phosphoric acid combines not only with inorganic bases to form salts, but with alcohols to form esters. In the middle of the 19th century, Théophile Juste Pelouze (1807-1867) extended this knowledge to an ester of glycerol. This proved to be significant in several respects. Glycerol had been shown by Michel Chevreul (1786-1889) as the substance in fats that is released in the process of soap boiling, when the fatty acids are converted into their salts. That it has the nature of an alcohol had been demonstrated by Marcellin Berthelot. Instead of one "alcoholic" hydroxyl group, OH, like ethanol (the alcohol of fermentation), or two hydroxyl groups (like ethylene glycol), glycerol contains three such groups. It was the only "natural" alcohol known at that time. That this alcohol would combine with phosphoric acid could be predicted, but that the ester, as obtained by Pelouze, still contained free acidic functions and formed a water-soluble barium salt was a new experience.
ALCOHOLIC FERMENTATION
(C_{6}H_{10}O_{5})_{_n_} C_{6}H_{12}O_{6} C_{6}H_{12}O_{6} glycogen glucose fructose ^| ^| ^| || H_{3}PO_{4} || <-- ATP || <--ATP |v |v |v ---------------+ ------+ H--C--OPO_{3}H_{2}| H--C--OH | H _{2}C--OH | | | | | H--C--OH | H--C--OH | C--(OH)--+ | | | | | | HO--C--H O <==> HO--C--H O <=======> HO--C--H | | | | | | O H--C--OH | H--C--OH | H--C--OH | | | | | | | H--C--------------+ H--C-----+ H--C--------+ | | | CH_{2}OH H_{2}C--OPO_{3}H_{2}+ADP H_{2}C--OPO_{3}H_{2}+ADP
glucose-1-phosphate glucose-6-phosphate fructose-6-phosphate (Cori-ester) (Robison-ester) (Neuberg-ester) ^ | | | <-- ATP +----| | | +------| | | | v H_{2}C--OPO_{3}H_{2} | C(OH)--+ | | HO--C--H | fructose-1,6-diphosphate | O (Harden-Young-ester) H--C--OH | | | H--C------+ | H_{2}C--OPO_{3}H_{2} + ADP ^| || O || // CH_{2}OPO_{3}H_{2} || CH | |v | 3-phosphoglycer-aldehyde dihydroxyacetone-phosphate C=O <=============> CHOH (Fischer-ester) | | CH_{2}OH CH_{2}OPO_{3}H_{2} || + coenzyme + H_{3}PO_{4} O=C--OPO_{3}H_{2} | 1,3-diphosphoglyceric acid CHOH + dihydro-coenzyme (Negelein-ester) | CH_{2}OPO_{3}H ^| ADP --> || || O |v// C--OH | +---+ 3-phosphoglyceric acid CHOH + |ATP| (Nilsson-ester) | +---+ CH_{2}OPO_{3}H_{2} ^| |v COOH 2-phosphoglyceric acid | CHOPO_{3}H_{2} | CH_{2}OH ^| |v COOH | phosphopyruvic acid COPO_{3}H_{2} (enol-) || CH_2 ADP --> || COOH +------+ | +---+ |CO_{2}| + CH_3CHO <-------- C=O + |ATP| +------+ acetaldehyde | +---+ carbon | CH_{3} dioxide | + dihydro-coenzyme pyruvic acid | v +----------------+ | CH_{3}CH_{2}OH | + coenzyme +----------------+ ethyl alcohol
Shortly after this experience had been gained, it became valuable for understanding the chemical nature of a new substance extracted from a natural organ. This substance was named lecithin by its discoverer, Nicolas Théodore Gobley[27] (1811-1876), because he obtained it from egg yolk (in Greek, _lékidos_). He used ether and alcohol for this extraction. Had he used water and mineral acid instead, he would not have found lecithin, but only its components. As Gobley and, slightly later, Oscar Liebreich (1839-1908), subjected lecithin to treatment with boiling water and acid, they separated it into three parts. One of them was the glycerophosphoric acid of Pelouze, the second was the well-known stearic acid of Chevreul, but the third was somewhat mysterious. This third substance was the same as one previously noticed when nerves had been subjected to an extraction by boiling water and acid and, therefore, called nerve-substance or neurine. Adolf Friedrich Strecker (1822-1871) established the identity of this neurine with a product he had extracted from bile and which went under the name of choline. Adolphe Wurtz (1817-1884) succeeded in synthesizing this substance from ethylene oxide, CH_2.O.CH_2 and trimethylamine N(CH_3)_3.[28] Thus, all three parts were identified, and Strecker put them together to construct a chemical formula for lecithin, glycerophosphoric acid combined with a fatty acid and with choline (a hydrate of neurine).
{ OH } N { (CH_3)_3 } Choline { C_2H_4O }
C_18H_33O_2 } HO } } } PO C_16H_31O_2 } C_3H_5O }
Fatty Acids Glycerophosphate \--------v-------/ Lecithin according to Strecker
This formula was not quite correct. Richard Willstätter showed that an internal neutralization takes place between the amino group and the free acidic residue. This is expressed in his lecithin formula of 1918.
CH_{2}·O·R | CH_{2}·O·R_2 | | O·CH_{2}·CH_{2} | / \ CH_{2}·O--P=O N(CH_{3})_{3} \ / \---O----/
When the aim was to distill elementary phosphorus out of an organic material, it did not matter whether this was fresh or putrified. For obtaining lecithin out of egg yolk and similar materials, it was essential to use it in fresh condition. Otherwise, enzymes would have decomposed it. Through more recent work, four enzymes have been separated, which act specifically in decomposing lecithin. Enzyme A removes one fatty acid and leaves a complex residue, called lysolecithin, intact. Enzyme B attacks this residue and splits off the remaining fatty acid group from it, enzyme C liberates only the choline from lecithin, and enzyme D opens lecithin at the ester bond between glycerol and phosphoric acid. This is shown in the following diagram.
ENZYMATIC SPLITTING OF LECITHINS
ENZYME SUBSTRATE PRODUCTS
A Lecithin Lysolecithin and fatty acids.
B Lysolecithin Glycero-phospho-choline and fatty acids.
C Lecithin Phosphatidic acid and choline.
D Lecithin Phosphoryl choline and diglyceride.
Several fatty acids can be present in lecithin from various sources: palmitic and oleic acid, besides the stearic acid which at first had been thought the only one involved. In another group of extracts from brain or nerve tissue, amino-ethanol H_{2}NCH_{2}CH_{2}OH is found instead of the choline of lecithin. The variations include the alcohol, to which the fatty acids and choline phosphate are attached, for example, glycerol can be replaced by the so-called meat-sugar, inositol, which has six hydroxyl groups in its hexagon-shaped molecule C_{6}H_{6}(OH)_{6}.
The generally similar behavior of these phosphate-and fat-containing substances was emphasized by Ludwig Thudichum (1829-1901). He coined the name phosphatides for this group of substances from seeds and nerves.[29] His work on the phosphates in brain substance aroused particular interest. When William Crookes drew his highly imaginative picture of an "evolution" of the chemical elements, he put into it "phosphorus for the brain, salt for the sea, clay for the solid earth...."[30] But phosphatides occur in many places of organisms, in bacteria, in leaves and roots of plants, in fat and tissues of animals. And where phosphatides are found, there are also enzymes that specifically act on them. They are called phosphatases to imply that they split the phosphatides. In addition, enzymes are present, which transfer phosphate groups from one compound to another. They are more abundant in seeds of high fat content than in the more starch-containing seeds, but even potatoes and orange juice have phosphatases.[31]
Thus, from phosphatides, phosphoric acid is generated, and they could also be called phosphagens. Since 1926, however, the name phosphagens has been reserved for a group of organic substances that release their phosphoric acid very readily. The link between phosphorus and carbon is provided by oxygen in the phosphatides, by nitrogen in the phosphagens. In vertebrates, the basis for the phosphoric acid is creatine, whereas invertebrates have arginine instead.
H OH OH | / / N--P=O NH--P=O / \ / \ C=NH OH C=NH OH \ \ N--CH_{2}COOH NH | | CH_{3} CH_{2} | Creatine phosphate CH_{2} | CH_{2} | CHNH_{2} | COOH
Arginine phosphate
Nuclein and Nucleic Acids
All parts of an organism are essential for life. Only with this in mind does it make sense to say that the most important part of the cell is its nucleus. From the nuclei of cells in pus and in salmon sperm, Johann Friedrich Miescher (1811-1887) obtained a peculiar kind of substance, which he named nuclein (1868). Its phosphate content was easily discovered, but to find the exact proportions and the nature of the other components required special methods of separation from phosphatides and other proteins. It was difficult to develop such methods at a time when little was known about the properties, and particularly the stability, of a nuclein. For preparing nuclein from yeast cells, Felix Hoppe-Seyler (1825-1895) described the following details: Yeast is dispersed in water to extract soluble materials, like salts or sugars. After a few hours, the insoluble material is separated, washed once more with water, and then extracted with a very dilute solution of sodium hydroxide. The slightly alkaline solution, freed from insoluble residues, is slowly added to a weak hydrochloric acid. A precipitate forms which is separated by filtration, washed with dilute acid, then with cold alcohol, and finally extracted by boiling alcohol. The dried residue is the nuclein.[32] It contains six percent phosphorus. A little more washing with water, a slightly longer treatment with acid or alcohol gives products of lower phosphorus content. Many experimental variations were necessary to establish the procedure that leads to purification without alteration of the natural substance.
This was also true for the methods of chemical degradation, carried out in order to find the components of nucleins in their highest state of natural complexity. It was learned for example, that the special kind of carbohydrate present in nucleins was very susceptible to change under the conditions of hydrolysis by acids. Phoebus Aaron Theodor Levine (1869-1940), therefore, used the digestion by a living organism. With E. S. London, he introduced a solution of nucleic acid into, e.g., the gastrointestinal segment of a dog through a gastric fistula and withdrew the product of digestion through an intestinal fistula. Fortunately, the products obtained in such degradations were not new in themselves. The carbohydrate in this nucleic acid proved to be identical with D-ribose, which Emil Fischer had artificially made from arabinose and named ribose to indicate this relationship (1891). The nitrogenous products of the degradation were identical with substances previously prepared in the long study of uric acid. In the course of this study, Emil Fischer established uric acid and a number of its derivatives as having the elementary skeleton of what he called "pure uric acid," abbreviated to purine. Out of Adolf Baeyer's work on barbituric acid came the knowledge of pyrimidine and its derivatives.
From these findings, together with what Oswald Schmiedeberg (1838-1921) had established concerning the presence of four phosphate groups in the molecule (1899), Robert Feulgen (1884-1955) constructed the following scheme of a nucleic acid. Feulgen's formula of 1918 is:
Phosphoric acid--Carbohydrate--Guanine Phosphoric acid--Carbohydrate--Cytosine Phosphoric acid--Carbohydrate--Thymine Phosphoric acid--Carbohydrate--Adenine
Of the four basic components on the right, thymine occurs in the nucleic acid from the thymus gland. Yeast contains uracil instead. The difference between these two bases is one methyl group: thymine is a 5-methyluracil. In all of these basic substances, the structure of urea
NH_{2} / C=O \ NH_{2}
is involved, and they form pairs of oxidized and reduced states:
PURINE PYRIMIDINE
(reduced) Adenine + (oxidized) Thymine (oxidized) Guanine + (reduced) Cytosine
3N = CH4 | | 2H--C CH5 || || 1N--CH6
Pyrimidine
1N==CH6 | | H | | 7/ N==C--NH_{2} 2H--C C--N | | || ||5 \ H--C C--NH || || \ || || \ || || CH8 || || CH || || // || || // 3N--C--N N--C--N 4 9 Adenine Purine
HN--C=O | | NH_{2}--C C--NH N==C--NH_{2} H--N--C=O || || \ | | | | || || CH O=C C--H O=C CH || || // | || | || N--C--N H--N--CH HN--CH
Guanine Cytosine Uracil
The carbohydrate is ribose or deoxyribose.
CHO CHO | | H--C--OH HO--C--H | | HO--C--H HO--C--H | | HO--C--H HO--C--H | | CH_{2}OH CH_{2}OH
Arabinose L-Ribose
Fischer and Piloty, 1891
H \(1)/-----O-----\(4) (5) C CH--CH_{2}OH / \(2) (3)/ HO CH_{2}--HC(OH)
Deoxyribose
The exact position of phosphoric acid was established after long work and verified by synthesis.[33]
A compound of adenine, ribose, and phosphoric acid was found in yeast, blood, and in skeletal muscle of mammals. From 100 grams of such muscle, 0.35-0.40 grams of this compound were isolated. If the muscle is at rest, the compound contains three molecules of phosphoric acid, linked through oxygen atoms. It was named adenosine triphosphate or adenyltriphosphoric acid,[34] usually abbreviated by the symbol ATP. It releases one phosphoric acid group very easily and goes over in the diphosphate, ADP, but it can also lose 2 P-groups as pyrophosphoric acid and leave the monophosphate, AMP.
N==C--NH_{2} | | HC C--N +----O----+ || || \\ | | || || CH | OH OH | H OH || || / | | | | | / N--C--N-----C--C---C--C--C--O--P=O | | | | | \ H H H H H OH \---------/\---------------/\--------/ Adenine D-Ribose Phosphoric acid
This change of ATP was considered to be the main source of energy in muscle contraction by Otto Meyerhof.[35] The corresponding derivatives of guanine, cytosine, and uracil were also found, and they are active in the temporary transfer of phosphoric acid groups in biological processes.
Thus, the study of organic phosphates progressed from the comparatively simple esters connected with fatty substances of organisms to the proteins and the nuclear substances of the cell. The proportional amount of phosphorus in the former was larger than in the latter; the actual importance and function in the life of organisms, however, is not measured by the quantity but determined by the special nature of the compounds.
The study of this function is the newest phase in the history of phosphorus and represents the culmination of the previous efforts. This newest phase developed out of an accidental discovery concerning one of the oldest organic-chemical industries, the production of alcohol by the fermentative action of yeast on sugar. A transition of carbohydrates through phosphate compounds to the end products of the fermentation process was found, and it gradually proved to be a kind of model for a host of biological processes.
Specific phosphates were thus found to be indispensable for life. In reverse, the wrong kind of phosphates can destroy life. As a result, an important part of the new phase in phosphorus history consisted in the study--and use--of antibiotic phosphorus compounds.
Phosphates in Biological Processes
The first indication that phosphorus is important for life came from the experience that plants take it up from the substances in the soil. They incorporate it in their body substance. What makes phosphorus so important that they cannot grow without it? The next insight was that animals acquire it from their plant food. It is then found in bones, in fat and nerve tissue, in all cells and particularly in the cell nuclei. What are its functions there?
The answers to such questions were developed from the study of a long-known process, the conversion of carbohydrates into carbon dioxide and alcohol by yeast. It started with Eduard Buchner's discovery of 1890, that fermentation is produced by a preparation from yeast in which all living cells have been removed. When yeast is dead-ground and pressed out, the juice still has the ability to produce fermentation.
It is strange, but in many ways characteristic for the process of science, that the "riddle" of phosphorus in life was solved by first eliminating life. In such "lifeless" fermentations, Arthur Harden found that the conversion of sugar begins with the formation of a hexose phosphate (1904). The "ferment" of yeast, called zymase, proved to be a composite of several enzymes. Hans von Euler-Chelpin isolated one part of zymase, which remains active even after heating its solution to the boiling point. From 1 kilogram of yeast, he obtained 20 milligrams of this heat-stable enzyme, which he called cozymase and identified as a nucleotide composed of a purine, a sugar, and phosphoric acid.[36] In the years between the two World Wars, zymase was further resolved into more enzymes, one of them the coenzyme I, which was shown to be ADP connected with another molecule of ribose attached to the amide of nicotinic acid, or diphosphopyridine nucleotide:
^ NH_{2} / \\ | / \\ N ^ || |-CONH_{2} //\ / \\ || | | || N \ // | || | N_{+} N--+ | | | \// | | N H--C------+ H--C------+ | | | | H--C--OH | H--C--OH | | O | O H--C--OH | H--C--OH | | | | | H--C------+ O O H--C------+ | || || | CH_{2}--O--P--O--P--O--CH_{2} | | O- OH
Coenzyme I
Its function is connected with the transfer of hydrogen between intermediates formed through phosphate-transferring enzymes. Fermentation proceeds by a cascade of processes, in which phosphate groups swing back and forth, and equilibria between ATP with ADP play a major role.
Many of the enzymes are closely related to vitamins. Thus, cocarboxylase A, which takes part in the separation of carbon dioxide from an intermediate fermentation product, is the phosphate of vitamin B_{1}. Others of the B vitamins contain phosphate groups, for example those of the B_{2} and B_{6} group, and in B_{12}, one lonely phosphate forms a bridge in the large molecule that contains one atom of cobalt: C_{63}H_{90}N_{14}O_{14}PCo. The formation of vitamin A from carotine occurs under the influence of ATP.
The first stages in fermentation are like those in respiration, which ends with carbon dioxide and water. These two are the materials for the reverse process in photosynthesis. When light is absorbed by the chlorophyll of green plants, one of the initial reactions is a transfer of hydrogen from water to a triphosphopyridine nucleotide, which later acts to reduce the carbon dioxide. Under the influence of ATP, phosphoglyceric acid is synthesized and further built up by way of carbohydrate phosphates to hexose sugars and finally to starch. In many starchy fruits, a small proportion of phosphate remains attached to the end product.
The synthesis of proteins is under the control of deoxyribonucleic acid or ribonucleic acid, abbreviated by the symbols DNA and RNA. The genes in the nucleus are parts of a giant DNA molecule. RNA is a universal constituent of all living cells. Where protein synthesis is intense, the content in RNA is high. Thus, the spinning glands of silkworms are extraordinarily rich in RNA.[37]
In his research on the radioactive isotope P^32, George de Hevesy gained some insight into the surprising mobility of phosphates in organisms: "A phosphate radical taken up with the food may first participate in the phosphorylation of glucose in the intestinal mucose, soon afterwards pass into the circulation as free phosphate, enter a red corpuscle, become incorporated with an adenosine triphosphoric-acid molecule, participate in a glycolytic process going on in the corpuscle, return to circulation, penetrate into the liver cells, participate in the formation of a phosphatide molecule, after a short interval enter the circulation in this form, penetrate into the spleen, and leave this organ after some time as a constituent of a lymphocyte. We may meet the phosphate radical again as a constituent of the plasma, from which it may find its way into the skeleton."[38] Much has been added in the last 30 years to complete this picture in many details and to extend it to other biochemical processes, including even the changes of the pigments in the retina in the visual process, or in the conversion of chemical energy to light by bacteria and insects.
Medicines and Poisons
In the delicate balance of these processes, disturbances may occur which can be remedied by specific phosphate-containing medicines. Thus, adenosine phosphate has been recommended in cases of angina pectoris and marketed under trade names like sarkolyt, or in compounds named angiolysine. A considerable number of physiologically active organic phosphates can be found in the patent literature.[39] Yeast itself is considered to be a valuable food additive.
On the other hand, there are phosphate compounds that act as poisons. One group of such compounds was discovered in 1929 by W. Lange, who wrote: "Of interest is the strong action of mono-fluorophosphate esters on the human body--the effect is produced by very small quantities."[40] Diisopropyl fluorophosphate has since become a potential agent for chemical warfare. It inactivates an enzyme which controls the transmission of nerve impulses to muscle, acetylcholine esterase.
Organic esters of phosphoric acids are used as insecticides. The hexa-ethylester of tetraphosphoric acid, prepared by Gerhard Schrader by heating triethylphosphate with phosphorus oxychloride,[41] actually contains tetraethylpyrophosphate (TEPP) among others. Bayer's Dipterex, the dimethyl ester of 2,2,2-trichloro-1-hydroxyethyl-phosphonate, has been modified to dimethyl-2,2-dichlorovinyl-phosphate and is especially active against the oriental fruit fly.[42]
Cl H O | | || OCH_{3} | | ||/ Cl--C--C--P Bayer's L 13/59 | | \ (Dipterex) | | OCH_{3} Cl OH
(CH_{3})_{2}N O O N(CH_{3})_{2} \|| ||/ P--O--P Schradan / \ (CH_{3})_{2}N N(CH_{3})_{2}
Octamethylpyrophosphoramide
The story of phosphorus, which began 300 years ago, has acquired new importance in this century. Many scientists have contributed to it: 13 of them have received Nobel Prizes for work directly bearing on the chemical and biological importance of phosphorus compounds. In chronological order, they are: Eduard Buchner, Albrecht Kossel, Otto Meyerhof, Arthur Harden, Hans von Euler-Chelpin, George de Hevesy, Carl F. Cori, Gerty T. Cori, Fritz Lipmann, Lord Alexander Todd, Arthur Kornberg, Severo Ochoa, and Melvin Calvin. The developers of industrial production and commercial utilization of phosphate compounds have had other rewards.
Some impression of the continuing growth in this field[43] can be gained from the following data.
PHOSPHATE ROCK
annually "sold or used by producer" in the United States in million long tons (2,240 lbs.)
1880 0.2 1890 0.5 1900 1.5 1910 2.655 1920 4.104 1930 3.926 1940 4.003 1945 5.807 1950 11.114 1955 12.265 1955 (world: about 56) 1960 17.202 1962 19.060
Sources: U.S. Bureau of the Census. _Historical Statistics of the United States 1789-1945_ (1949); _Statistical Abstract of the United States._
ELEMENTAL PHOSPHORUS
annually produced in the United States in short tons (2,000 lbs.)
1939 43,000 1944 85,679 1950 153,233 1956 312,200 1958 335,750 1959 366,350 1960 409,096 1961 430,617 1962 451,970
Source: U.S. Department of Commerce.
* * * * *
FOOTNOTES
[1] WILHELM HOMBERG, _Mémoires Académie, 1666-1699_ (Paris, 1730), vol. 10, under date of April 30, 1692, pp. 57-61.
[2] FORTUNIO LICETUS, _Lithiophosphorus sive de lapide Bononiensi_ (Venice, 1640).
[3] Cited in PETER JOSEPH MACQUER _Chymisches Wörterbuch_, 2nd ed. (Leipzig: Weidmann, 1789), vol. 4, p. 508, footnote "c" as "Kletwich (de phosph. liqu. et solid. 1689, Thes. II)."
[4] FERDINAND HOEFER, _Histoire de la Chimie_ (Paris, 1843), vol. 1, p. 339.
[5] G. W. VON LEIBNIZ, _Mémoires Académie_ (Paris, 1682); _Akademie der Wissenschaften, Miscellanea Berolinensia_ (Berlin, 1710), vol. 1, p. 91.
[6] JEAN HELLOT, _Mémoires Académie 1737_ (Paris, 1766), under date of November 13, 1737, pp. 342-378.
[7] MACQUER, op. cit. (footnote 3), p. 551.
[8] A. S. MARGGRAF, _Akademie der Wissenschaften, Miscellanea Berolinensia_ (Berlin, 1743), vol. 7, 342 ff.; see also WILHELM OSTWALD _Klassiker der Exakten Naturwissenschaften_ (Leipzig: Engelmann, 1913), no. 187.
[9] G. HANCKEWITZ, [Hankwitz], _Philosophical Transactions of the Royal Society of London_, 1724-1734, abridged (London, 1809), vol. 7, pp. 596-602.
[10] ANTOINE LAURENT LAVOISIER, "Sur la Combustion du Phosphore de Kunckel, Et sur la nature de l'acide qui resulte de cette Combustion," _Mémoires Académie 1777_, (Paris, 1780), pp. 65-78.
[11] GUYTON DE MORVEAU and others, _Méthode de Nomenclature Chimique_, Proposée par MM. de Morveau, Lavoisier, Bertholet, & de Fourcroy (Paris, 1787), plate 9.
[12] MACQUER, op. cit. (footnote 3), p. 513.
[13] MARIE BOAS, _Robert Boyle and Seventeenth Century Chemistry_ (New York: Cambridge University Press, 1958), p. 226; see also WYNDHAM MILES, "The History of Dr. Brand's Phosphorus Elementarus," _Armed Forces Chemical Journal_ (November-December 1958), p. 25.
[14] ARCHIBALD CLOW and NAN L. CLOW, _The Chemical Revolution_ (London: Batchworth Press, 1952), p. 451.
[15] ÉMILE KOPP, _Comptes-rendus hebdomadaires des Séances de l'Académie des Sciences, Paris_ (1844), vol. 18, p. 871; WILHELM HITTORF, _Annalen der Chemie und Pharmazie_, suppl. to vol. 4, p. 37; ANTON SCHRÖTTER, _Annales de Chimie et de Physique_, series 3, vol. 24 (1848), p. 406; see also Schrötter's report on "Phosphor und Zündwaaren" in A. W. VON HOFMANN, _Bericht über die Entwicklung der Chemischen Industrie_ (Braunschweig: Vieweg, 1875), pp. 219-246.
[16] R. GLAUBER, _Furni Novi Philosphici_ (Amsterdam, 1649), vol. 2, pp. 12 ff.
[17] HERMANN SCHELENZ, _Geschichte der Pharmazie_ (Berlin: Springer, 1904), p. 598.
[18] J. PERSONNE, _Comptes-rendus ..._, Paris (1869), vol. 68, pp. 543-546.
[19] A. WURTZ, _Dictionnaire de Chimie_ (Paris, 1876), vol. 2, part 2, p. 951.
[20] KARL W. SCHEELE, _Nachgelassene Briefe und Aufzeichnungen_, edit. A. E. Nordenskiöld (Stockholm: Norstedt, 1892), pp. 38, 144.
[21] J. J. BERZELIUS, _Lehrbuch_, transl. F. Wöhler (Dresden, 1827), vol. 3, part 1, p. 96.
[22] THOMAS GRAHAM, _Philosophical Transactions of the Royal Society of London_ (1833), pp. 253-284.
[23] JUSTUS LIEBIG'S _Annalen der Pharmacie_ (1838), vol. 26, p. 113 ff.
[24] A. WURTZ, _Annales de Chimie et de Physique_, series 3, vol. 16 (1846), p. 190.
[25] CARROLL D. WRIGHT, _The Phosphate Industry in the United States_, sixth special report of the Commissioner of Labor (Washington, 1893).
[26] J. STOKLASA, _Biochemischer Kreislauf des Phosphat-Ions im Boden, Centralblatt für Bakteriologie ..._ (Jena: Fischer, March 22, 1911), vol. 29, nos. 15-19.
[27] N. T. GOBLEY, _Comptes-rendus_ ..., Paris (1845), vol. 21, p. 718.
[28] A. WURTZ, _Comptes-rendus_ ..., Paris (1868), vol. 66, p. 772.
[29] L. THUDICHUM, _Die chemische Constitution des Gehirns des Menschen und der Tiere_ (1901); see also H. WITTCOFF, THE PHOSPHATIDES (New York: Reinhold, 1951).
[30] WILLIAM CROOKES, _British Association for the Advancement of Science, Reports_ (1887), sec. B, p. 573.
[31] J. E. COURTOIS and A. LINO, _Progress in the Chemistry of Organic Natural Products_, edit. L. Zechmeister (Vienna: Springer Verlag, 1961), vol. 19, p. 316-373.
[32] A. WURT, _Dictionnaire de Chimie_, supp. part 2, [n.d.] p. 1087; A. KOSSEL, _Zeitschrift für physiologische Chemie_, series 3 (1879), p. 284.
[33] ALEXANDER TODD, _Les Prix Nobel en 1957_ (Stockholm).
[34] HANS VON EULER-CHELPIN, _Les Prix Nobel en 1929_ (Stockholm).
[35] O. MEYERHOF and E. LUNDSGAARD, _Naturwissenschaften_ (Berlin, 1930), vol. 18, pp. 330, 787.
[36] K. LOHMANN, _Naturwissenschaften_ (Berlin, 1929), vol. 17, p. 624; C. H. FISKE and Y. SUBBAROW, _Science_ (Washington, 1929), vol. 70, p. 381 f.
[37] J. BRACHET, _Scientia, Revista di Scienza_ (1960), vol. 95, p. 119.
[38] GEORGE DE HEVESY, _Les Prix Nobel en 1940_ (Stockholm). See also EDUARD FARBER, _Nobel Prize Winners in Chemistry_, 2nd ed. (New York: Schuman, 1963), p. 179.
[39] See, e.g., _Chemical Week_, vol. 77 (September 3, 1955), p. 79 f.; J. BOLLE, _Chimie et Industrie_ (1960), vol. 83, p. 252.
[40] W. LANGE, _Berichte der Deutschen Chemischen Gesellschaft_ (Berlin, 1929), vol. 62, p. 793; vol. 65 (1932), p. 1598.
[41] GERHARD SCHRADER, U.S. patent 2,336,302 of 1943 (priority in Germany, 1938); S. A. HALL and M. JACOBSON, _Industrial and Engineering Chemistry_ (1943), vol. 40, p. 694.
[42] A. M. MATTSEN and others, _Journal of Agriculture and Food Chemistry_ (1955), vol. 3, p. 319.
[43] JOHN B. VAN WAZER, _Phosphorus and its Compounds_, 2 vols. (vol. 1, _Chemistry_; vol. 2 _Technology, Biological Functions and Applications_, New York: Interscience, 1958, 1961.
* * * * *
Paper 40 - Transcriber's Note
The following typographical errors have been corrected:
Page 180 "Abfällen, Vieweg, Braunschweig," - had "Viewig".
Page 188 "wires d from the dynamo D" - had "dynano".
Page 192 "But phosphatides occur" - had "phosphatide soccur".
Page 193 "the nucleic acid from the thymus" - had "nucleidic".
Page 199 "acetylcholine esterase." - had "acetylcholin".
Page 200 "George de Hevesy, Carl F. Cori," - comma added after Hevesy.
Footnote 39: "See, e.g., Chemical Week, vol. 77" - had "See. e.g."
The spelling of "Bertholet" [Claude Louis Berthollet] is as given on the original title page of the work referenced in this paper.
Inconsistent hyphenation of chemical names has been retained.
* * * * *
CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY.
PAPER 41
TUNNEL ENGINEERING--A MUSEUM TREATMENT
_Robert M. Vogel_
INTRODUCTION 203
ROCK TUNNELING 206
SOFT-GROUND TUNNELING 215
BIBLIOGRAPHY 239
FOOTNOTES
_Robert M. Vogel_
TUNNEL ENGINEERING--A MUSEUM TREATMENT
_During the years from 1830 to 1900, extensive developments took place in the field of tunneling, which today is an important, firmly established branch of civil engineering. This paper offers a picture of its growth from the historical standpoint, based on a series of models constructed for the Hall of Civil Engineering in the new Museum of History and Technology. The eight models described highlight the fundamental advances which have occurred between primitive man's first systematic use of fire for excavating rock in mining, and the use in combination of compressed air, an iron lining, and a movable shield in a subaqueous tunnel at the end of the 19th century._
THE AUTHOR: _Robert M. Vogel is curator of heavy machinery and civil engineering, in the Smithsonian Institution's Museum of History and Technology._
Introduction
With few exceptions, civil engineering is a field in which the ultimate goal is the assemblage of materials into a useful structural form according to a scientifically derived plan which is based on various natural and man-imposed conditions. This is true whether the result be, for example, a dam, a building, a bridge, or even the fixed plant of a railroad. However, one principal branch of the field is based upon an entirely different concept. In the engineering of tunnels the utility of the "structure" is derived not from the bringing together of elements but from the separation of one portion of naturally existing material from another to permit passage through a former barrier.
In tunneling hard, firm rock, this is practically the entire compass of the work: breaking away the rock from the mother mass, and, coincidently, removing it from the workings. The opposite extreme in conditions is met in the soft-ground tunnel, driven through material incapable of supporting itself above the tunnel opening. Here, the excavation of the tunneled substance is of relatively small concern, eclipsed by the problem of preventing the surrounding material from collapsing into the bore.
In one other principal respect does tunnel engineering differ widely from its collateral branches of civil engineering. Few other physical undertakings are approached with anything like the uncertainty attending a tunnel work. This is even more true in mountain tunnels, for which test borings frequently cannot be made to determine the nature of the material and the geologic conditions which will be encountered.
The course of tunnel work is not subject to an overall preliminary survey; the engineer is faced with not only the inability to anticipate general contingencies common to all engineering work, but with the peculiar and often overwhelming unpredictability of the very basis of his work.
Subaqueous and soft-ground work on the other hand, while still subject to many indeterminates, is now far more predictable than during its early history, simply because the nature of the adverse condition prevailing eventually was understood to be quite predictable. The steady pressures of earth and water to refill the excavated area are today overcome with relative ease and consistency by the tunneler.
In tunneling as in no other branch of civil engineering did empiricism so long resist the advance of scientific theory; in no other did the "practical engineer" remain to such an extent the key figure in establishing the success or failure of a project. The Hoosac Tunnel, after 25 years of legislative, financial, and technical difficulties, in 1875 was finally driven to successful completion only by the efforts of a group who, while in the majority were trained civil engineers, were to an even greater extent men of vast practical ability, more at home in field than office.
DeWitt C. Haskin (see p. 234), during the inquest that followed the death of a number of men in a blowout of his pneumatically driven Hudson River Tunnel in 1880, stated in his own defense: "I am not a scientific engineer, but a practical one ... I know nothing of mathematics; in my experience I have grasped such matters as a whole; I believe that the study of mathematics in that kind of work [tunneling] has a tendency to dwarf the mind rather than enlighten it...." An extreme attitude perhaps, and one which by no means adds to Haskin's stature, but a not unusual one in tunnel work at the time. It would not of course be fair to imply that such men as Herman Haupt, Brunel the elder, and Greathead were not accomplished theoretical engineers. But it was their innate ability to evaluate and control the overlying physical conditions of the site and work that made possible their significant contributions to the development of tunnel engineering.
Tunneling remained largely independent of the realm of mathematical analysis long after the time when all but the most insignificant engineering works were designed by that means. Thus, as structural engineering has advanced as the result of a flow of new theoretical concepts, new, improved, and strengthened materials, and new methods of fastening, the progress of tunnel engineering has been due more to the continual refinement of constructional techniques.
A NEW HALL OF CIVIL ENGINEERING
In the Museum of History and Technology has recently been established a Hall of Civil Engineering in which the engineering of tunnels is comprehensively treated from the historical standpoint--something not previously done in an American museum. The guiding precept of the exhibit has not been to outline exhaustively the entire history of tunneling, but rather to show the fundamental advances which have occurred between primitive man's first systematic use of fire for excavating rock in mining, and the use in combination of compressed air, iron lining, and a movable shield in a subaqueous tunnel at the end of the 19th century. This termination date was selected because it was during the period from about 1830 to 1900 that the most concentrated development took place, and during which tunneling became a firmly established and important branch of civil engineering and indeed, of modern civilization. The techniques of present-day tunneling are so fully related in current writing that it was deemed far more useful to devote the exhibit entirely to a segment of the field's history which is less commonly treated.
The major advances, which have already been spoken of as being ones of technique rather than theory, devolve quite naturally into two basic classifications: the one of supporting a mass of loose, unstable, pressure-exerting material--soft-ground tunneling; and the diametrically opposite problem of separating rock from the basic mass when it is so firm and solid that it can support its own overbearing weight as an opening is forced through it--rock, or hard-ground tunneling.
To exhibit the sequence in a thorough manner, inviting and capable of easy and correct interpretation by the nonprofessional viewer, models offered the only logical means of presentation. Six tunnels were selected, all driven in the 19th century. Each represents either a fundamental, new concept of tunneling technique, or an important, early application of one. Models of these works form the basis of the exhibit. No effort was made to restrict the work to projects on American soil. This would, in fact, have been quite impossible if an accurate picture of tunnel technology was to be drawn; for as in virtually all other areas of technology, the overall development in this field has been international. The art of mining was first developed highly in the Middle Ages in the Germanic states; the tunnel shield was invented by a Frenchman residing in England, and the use of compressed air to exclude the water from subaqueous tunnels was first introduced on a major work by an American. In addition, the two main subdivisions, rock and soft-ground tunneling, are each introduced by a model not of an actual working, but of one typifying early classical methods which were in use for centuries until the comparatively recent development of more efficient systems of earth support and rock breaking. Particular attention is given to accuracy of detail throughout the series of eight models; original sources of descriptive and graphic information were used in their construction wherever possible. In all cases except the introductory model in the rock-tunneling series, representing copper mining by early civilizations, these sources were contemporary accounts.
The plan to use a uniform scale of reduction throughout, in order to facilitate the viewers' interpretation, unfortunately proved impractical, due to the great difference in the amount of area to be encompassed in different models, and the necessity that the cases holding them be of uniform height. The related models of the Broadway and Tower Subways represent short sections of tunnels only 8 feet or so in diameter enabling a relatively large scale, 1-1/2 inches to the foot, to be used. Conversely, in order that the model of Brunel's Thames Tunnel be most effective, it was necessary to include one of the vertical terminal shafts used in its construction. These were about 60 feet in depth, and thus the much smaller scale of 1/4 inch to the foot was used. This variation is not as confusing as might be thought, for the human figures in each model provide an immediate and positive sense of proportion and scale.
Careful thought was devoted to the internal lighting of the models, as this was one of the critical factors in establishing, so far as is possible in a model, an atmosphere convincingly representative of work conducted solely by artificial light. Remarkable realism was achieved by use of plastic rods to conduct light to the tiny sources of tunnel illumination, such as the candles on the miners' hats in the Hoosac Tunnel, and the gas lights in the Thames Tunnel. No overscaled miniature bulbs, generally applied in such cases, were used. At several points where the general lighting within the tunnel proper has been kept at a low level to simulate the natural atmosphere of the work, hidden lamps can be operated by push-button in order to bring out detail which otherwise would be unseen.
The remainder of the material in the Museum's tunneling section further extends the two major aspects of tunneling. Space limitations did not permit treatment of the many interesting ancillary matters vital to tunnel engineering, such as the unique problems of subterranean surveying, and the extreme accuracy required in the triangulation and subsequent guidance of the boring in long mountain tunnels; nor the difficult problems of ventilating long workings, both during driving and in service; nor the several major methods developed through the years for driving or constructing tunnels in other than the conventional manner.[1]
Rock Tunneling
While the art of tunneling soft ground is of relatively recent origin, that of rock tunneling is deeply rooted in antiquity. However, the line of its development is not absolutely direct, but is more logically followed through a closely related branch of technology--mining. The development of mining techniques is a practically unbroken one, whereas there appears little continuity or relationship between the few works undertaken before about the 18th century for passage through the earth.
The Egyptians were the first people in recorded history to have driven openings, often of considerable magnitude, through solid rock. As is true of all major works of that nation, the capability of such grand proportion was due solely to the inexhaustible supply of human power and the casual evaluation of life. The tombs and temples won from the rock masses of the Nile Valley are monuments of perseverance rather than technical skill. Neither the Egyptians nor any other peoples before the Middle Ages have left any consistent evidence that they were able to pierce ground that would not support itself above the opening as would firm rock. In Egypt were established the methods of rock breaking that were to remain classical until the first use of gun-powder blasting in the 17th century which formed the basis of the ensuing technology of mining.
Notwithstanding the religious motives which inspired the earliest rock excavations, more constant and universal throughout history has been the incentive to obtain the useful and decorative minerals hidden beneath the earth's surface. It was the miner who developed the methods introduced by the early civilizations to break rock away from the primary mass, and who added the refinements of subterranean surveying and ventilating, all of which were later to be assimilated into the new art of driving tunnels of large diameter. The connection is the more evident from the fact that tunnelmen are still known as miners.
COPPER MINING, B.C.
Therefore, the first model of the sequence, reflecting elemental rock-breaking techniques, depicts a hard-rock copper mine (fig. 1). Due to the absence of specific information about such works during the pre-Christian eras, this model is based on no particular period or locale, but represents in a general way, a mine in the Rio Tinto area of Spain where copper has been extracted since at least 1000 B.C. Similar workings existed in the Tirol as early as about 1600 B.C. Two means of breaking away the rock are shown: to the left is the most primitive of all methods, the hammer and chisel, which require no further description. At the right side, the two figures are shown utilizing the first rock-breaking method in which a force beyond that of human muscles was employed, the age-old "fire-setting" method. The rock was thoroughly heated by a fierce fire built against its face and then suddenly cooled by dashing water against it. The thermal shock disintegrated the rock or ore into bits easily removable by hand.
The practice of this method below ground, of course, produced a fearfully vitiated atmosphere. It is difficult to imagine whether the smoke, the steam, or the toxic fumes from the roasting ore was the more distressing to the miners. Even when performed by labor considered more or less expendable, the method could be employed only where there was ventilation of some sort: natural chimneys and convection currents were the chief sources of air circulation. Despite the drawbacks of the fire system, its simplicity and efficacy weighed so heavily in its favor that its history of use is unbroken almost to the present day. Fire setting was of greatest importance during the years of intensive mining in Europe before the advent of explosive blasting, but its use in many remote areas hardly slackened until the early 20th century because of its low cost when compared to powder. For this same reason, it did have limited application in actual tunnel work until about 1900.
Direct handwork with pick, chisel and hammer, and fire setting were the principal means of rock removal for centuries. Although various wedging systems were also in favor in some situations, their importance was so slight that they were not shown in the model.
HOOSAC TUNNEL
It was possible in the model series, without neglecting any major advancement in the art of rock tunneling, to complete the sequence of development with only a single additional model. Many of the greatest works of civil engineering have been those concerned directly with transport, and hence are the product of the present era, beginning in the early 19th century. The development of the ancient arts of route location, bridge construction, and tunnel driving received a powerful stimulation after 1800 under the impetus of the modern canal, highway, and, especially, the railroad.
The Hoosac Tunnel, driven through Hoosac Mountain in the very northwest corner of Massachusetts between 1851 and 1875, was the first major tunneling work in the United States. Its importance is due not so much to this as to its being literally the fountainhead of modern rock-tunneling technology. The remarkable thing is that the work was begun using methods of driving almost unchanged during centuries previous, and was completed twenty years later by techniques which were, for the day, almost totally mechanized. The basic pattern of operation set at Hoosac, using pneumatic rock drills and efficient explosives, remains practically unchanged today.
The general history of the Hoosac project is so thoroughly recorded that the briefest outline of its political aspects will suffice here. Hoosac Mountain was the chief obstacle in the path of a railroad projected between Greenfield, Massachusetts, and Troy, New York. The line was launched by a group of Boston merchants to provide a direct route to the rapidly developing West, in competition with the coastal routes via New York. The only route economically reasonable included a tunnel of nearly five miles through the mountain--a length absolutely without precedent, and an immense undertaking in view of the relatively primitive rock-working methods then available.
The bore's great length and the desire for rapid exploitation inspired innovation from the outset of the work. The earliest attempts at mechanization, although ineffectual and without influence on tunnel engineering until many years later, are of interest. These took the form of several experimental machines of the "full area" type, intended to excavate the entire face of the work in a single operation by cutting one or more concentric grooves in the rock. The rock remaining between the grooves was to be blasted out. The first such machine tested succeeded in boring a 24-foot diameter opening for 10 feet before its total failure. Several later machines proved of equal merit.[2] It was the Baltimore and Ohio's eminent chief engineer, Benjamin H. Latrobe, who in his _Report on the Hoosac Tunnel_ (Baltimore, Oct. 1, 1862, p. 125) stated that such apparatus contained in its own structure the elements of failure, "... as they require the machines to do too much and the powder too little of the work, thus contradicting the fundamental principles upon which all labor-saving machinery is framed ... I could only look upon it as a misapplication of mechanical genius."
Latrobe stated the basic philosophy of rock-tunnel work. No mechanical agent has ever been able to improve upon the efficiency of explosives for the shattering of rock. For this reason, the logical application of machinery to tunneling was not in replacing or altering the fundamental process itself, but in enabling it to be conducted with greater speed by mechanically drilling the blasting holes to receive the explosive.
Actual work on the Hoosac Tunnel began at both ends of the tunnel in about 1854, but without much useful effect until 1858 when a contract was let to the renowned civil engineer and railroad builder, Herman Haupt of Philadelphia. Haupt immediately resumed investigations of improved tunneling methods, both full-area machines and mechanical rock drills. At this time mechanical rock-drill technology was in a state beyond, but not far beyond, initial experimentation. There existed one workable American machine, the Fowle drill, invented in 1851. It was steam-driven, and had been used in quarry work, although apparently not to any commercial extent. However, it was far too large and cumbersome to find any possible application in tunneling. Nevertheless, it contained in its operating principle, the seed of a practical rock drill in that the drill rod was attached directly to and reciprocated by a double-acting steam piston. A point of great importance was the independence of its operation on gravity, permitting drilling in any direction.
While experimenting, Haupt drove the work onward by the classical methods, shown in the left-hand section of the model (fig. 2). At the far right an advance heading or adit is being formed by pick and hammer work; this is then deepened into a top heading with enough height to permit hammer drilling, actually the basic tunneling operation. A team is shown "double jacking," i.e., using two-handed hammers, the steel held by a third man. This was the most efficient of the several hand-drilling methods. The top-heading plan was followed so that the bulk of the rock could be removed in the form of a bottom bench, and the majority of drilling would be downward, obviously the most effective direction. Blasting was with black powder and its commercial variants. Some liberty was taken in depicting these steps so that both operations might be shown within the scope of the model: in practice the heading was kept between 400 and 600 feet in advance of the bench so that heading blasts would not interfere with the bench work. The bench carriage simply facilitated handling of the blasted rock. It was rolled back during blasts.
The experiments conducted by Haupt with machine drills produced no immediate useful results. A drill designed by Haupt and his associate, Stuart Gwynn, in 1858 bored hard granite at the rate of 5/8 inch per minute, but was not substantial enough to bear up in service. Haupt left the work in 1861, victim of intense political pressures and totally unjust accusations of corruption and mismanagement. The work was suspended until taken over by a state commission in 1862. Despite frightful ineptitude and very real corruption, this period was exceedingly important in the long history both of Hoosac Tunnel and of rock tunneling in general.
The merely routine criticism of the project had by this time become violent due to the inordinate length of time already elapsed and the immense cost, compared to the small portion of work completed. This served to generate in the commission a strong sense of urgency to hurry the project along. Charles S. Storrow, a competent engineer, was sent to Europe to report on the progress of tunneling there, and in particular on mechanization at the Mont Cenis Tunnel then under construction between France and Italy. Germain Sommeiller, its chief engineer, had, after experimentation similar to Haupt's, invented a reasonably efficient drilling machine which had gone into service at Mont Cenis in March 1861. It was a distinct improvement over hand drilling, almost doubling the drilling rate, but was complex and highly unreliable. Two hundred drills were required to keep 16 drills at work. But the vital point in this was the fact that Sommeiller drove his drills not with steam, but air, compressed at the tunnel portals and piped to the work face. It was this single factor, one of application rather than invention, that made the mechanical drill feasible for tunneling.
All previous effort in the field of machine drilling, on both sides of the Atlantic, had been directed toward steam as the motive power. In deep tunnels, with ventilation already an inherent problem, the exhaust of a steam drill into the atmosphere was inadmissible. Further, steam could not be piped over great distances due to serious losses of energy from radiation of heat, and condensation. Steam generation within the tunnel itself was obviously out of the question. It was the combination of a practical drill, and the parallel invention by Sommeiller of a practical air compressor that resulted in the first workable application of machine rock drilling to tunneling.
The Sommeiller drills greatly impressed Storrow, and his report of November 1862 strongly favored their adoption at Hoosac. It is curious however, that not a single one was brought to the U.S., even on trial. Storrow does speak of Sommeiller's intent to keep the details of the machine to himself until it had been further improved, with a view to its eventual exploitation. The fact is, that although workable, the Sommeiller drill proved to be a dead end in rock-drill development because of its many basic deficiencies. It did exert the indirect influence of inspiration which, coupled with a pressing need for haste, led to renewed trials of drilling machinery at Hoosac. Thomas Doane, chief engineer under the state commission, carried this program forth with intensity, seeking and encouraging inventors, and himself working on the problem. The pattern of the Sommeiller drill was generally followed; that is, the drill was designed as a separate, relatively light mechanical element, adapted for transportation by several miners, and attachable to a movable frame or carriage during operation. Air was of course the presumed power. To be effective, it was necessary that a drill automatically feed the drill rod as the hole deepened, and also rotate the rod automatically to maintain a round, smooth hole. Extreme durability was essential, and usually proved the source of a machine's failure. The combination of these characteristics into a machine capable of driving the drill rod into the rock with great force, perhaps five times per second, was a severe test of ingenuity and materials. Doane in 1864 had three different experimental drills in hand, as well as various steam and water-powered compressors.
Success finally came in 1865 with the invention of a drill by Charles Burleigh, a mechanical engineer at the well-known Putnam Machine Works of Fitchburg, Massachusetts. The drills were first applied in the east heading in June of 1866. Although working well, their initial success was limited by lack of reliability and a resulting high expense for repairs. They were described as having "several weakest points." In November, these drills were replaced by an improved Burleigh drill which was used with total success to the end of the work. The era of modern rock tunneling was thus launched by Sommeiller's insight in initially applying pneumatic power to a machine drill, by Doane's persistence in searching for a thoroughly practical drill, and by Burleigh's mechanical talent in producing one. The desperate need to complete the Hoosac Tunnel may reasonably be considered the greatest single spur to the development of a successful drill.
The significance of this invention was far reaching. Burleigh's was the first practical mechanical rock drill in America and, in view of its dependability, efficiency, and simplicity when compared to the Sommeiller drill, perhaps in the world. The Burleigh drill achieved success almost immediately. It was placed in production by Putnam for the Burleigh Rock Drill Company before completion of Hoosac in 1876, and its use spread throughout the western mining regions and other tunnel works. For a major invention, its adoption was, in relative terms, instantaneous. It was the prototype of all succeeding piston-type drills, which came to be known generically as "burleighs," regardless of manufacture. Walter Shanley, the Canadian contractor who ultimately completed the Hoosac, reported in 1870, after the drills had been in service for a sufficient time that the techniques for their most efficient use were fully understood and effectively applied, that the Burleigh drills saved about half the drilling costs over hand drilling. The per-inch cost of machine drilling averaged 5.5 cents, all inclusive, vs. 11.2 cents for handwork. The more important point, that of speed, is shown by the reports of average monthly progress of the tunnel itself, before and after use of the air drills.
_Year_ _Average monthly progress in feet_
1865 55 1866 48 1867 99 1868 -- 1869 138 1870 126 1871 145 1872 124
The right portion of the model (fig. 3) represents the workings during the final period. The bottom heading system was generally used after the Burleigh drills had been introduced. Four to six drills were mounted on a carriage designed by Doane. These drove the holes for the first blast in the center of the heading in about six hours. The full width of the heading, the 24-foot width of the tunnel, was then drilled and blasted out in two more stages. As in the early section, the benches to the rear were later removed to the full-tunnel height of about 20 feet. This operation is shown by a single drill (fig. 4) mounted on a screw column. Three 8-hour shifts carried the work forward: drilling occupied half the time and half was spent in running the carriage back, blasting, and mucking (clearing the broken rock).
The tunnel's 1028-foot central shaft, completed under the Shanley contract in 1870 to provide two additional work faces as well as a ventilation shaft is shown at the far right side of this half of the model. Completed so near the end of the project, only 15 percent of the tunnel was driven from the shaft.
The enormous increase in rate of progress was not due entirely to machine drilling. From the outset of his jurisdiction, Doane undertook experiments with explosives as well as drills, seeking an agent more effective than black powder. In this case, the need for speed was not the sole stimulus. As the east and west headings advanced further and further from the portals, the problem of ventilation grew more acute, and it became increasingly difficult to exhaust the toxic fumes produced by the black powder blasts.
In 1866, Doane imported from Europe a sample of trinitroglycerine, the liquid explosive newly introduced by Nobel, known in Europe as "glonoïn oil" and in the United States as "nitroglycerine." It already had acquired a fearsome reputation from its tendency to decompose with heat and age and to explode with or without the slightest provocation. Nevertheless, its tremendous power and characteristic of almost complete smokelessness led Doane to employ the chemist George W. Mowbray, who had blasted for Drake in the Pennsylvania oil fields, to develop techniques for the bulk manufacture of the new agent and for its safe employment in the tunnel.
Mowbray established a works on the mountain and shortly developed a completely new blasting practice based on the explosive. Its stability was greatly increased by maintaining absolute purity in the manufacturing process. Freezing the liquid to reduce its sensitivity during transport to the headings, and extreme caution in its handling further reduced the hazard of its use. At the heading, the liquid was poured into cylindrical cartridges for placement in the holes. As with the Burleigh drill, the general adoption of nitroglycerine was immediate once its qualities had been demonstrated. The effect on the work was notable. Its explosive characteristics permitted fewer blast holes over a given frontal area of working face, and at the same time it was capable of effectively blowing from a deeper drill hole, 42 inches against 30 inches for black powder, so that under ideal conditions 40 percent more tunnel length was advanced per cycle of operations. A new fuse and a system of electric ignition were developed which permitted simultaneous detonation and resulted in a degree of effectiveness impossible with the powder train and cord fusing used with the black powder. Over a million pounds of nitroglycerine were produced by Mowbray between 1866 and completion of the tunnel.
When the Shanleys took the work over in 1868, following political difficulties attending operation by the State, the period of experimentation was over. The tunnel was being advanced by totally modern methods, and to the present day the overall concepts have remained fundamentally unaltered: the Burleigh piston drill has been replaced by the lighter hammer drill; the Doane drill carriage by the more flexible "jumbo"; nitroglycerine by its more stable descendant dynamite and its alternatives; and static-electric blasting machines by more dependable magnetoelectric. But these are all in the nature of improvements, not innovations.
Unlike the preceding model, there was good documentation for this one. Also, the Hoosac was apparently the first American tunnel to be well recorded photographically. Early flashlight views exist of the drills working at the heading (fig. 6) as well as of the portals, the winding and pumping works at the central shaft, and much of the machinery and associated aspects of the project. These and copies of drawings of much of Doane's experimental apparatus, a rare technological record, are preserved at the Massachusetts State Library.
Soft-Ground Tunneling
So great is the difference between hard-rock and soft-ground tunneling that they constitute two almost separate branches of the field. In penetrating ground lacking the firmness or cohesion to support itself above an opening, the miner's chief concern is not that of removing the material, but of preventing its collapse into his excavation. The primitive methods depending upon brute strength and direct application of fire and human force were suitable for assault on rock, but lacked the artifice needed for delving into less stable material. Roman engineers were accomplished in spanning subterranean ways with masonry arches, but apparently most of their work was done by cut-and-cover methods rather than by actual mining.
Not until the Middle Ages did the skill of effectively working openings in soft ground develop, and not until the Renaissance was this development so consistently successful that it could be considered a science.
RENAISSANCE MINING
From the earliest periods of rock working, the quest for minerals and metals was the primary force that drove men underground. It was the technology of mining, the product of slow evolution over the centuries, that became the technology of the early tunnel, with no significant modification except in size of workings.
Every aspect of 16th century mining is definitively detailed in Georgius Agricola's remarkable _De re Metallica_, first published in Basel in 1556. During its time of active influence, which extended for two centuries, it served as the authoritative work on the subject. It remains today an unparalleled early record of an entire branch of technology. The superb woodcuts of mine workings and tools in themselves constitute a precise description of the techniques of the period, and provided an ideal source of information upon which to base the first model in the soft-ground series.
The model, representing a typical European mine, demonstrates the early use of timber frames or "sets" to support the soft material of the walls and roof. In areas of only moderate instability, the sets alone were sufficient to counteract the earth pressure, and were spaced according to the degree of support required. In more extreme conditions, a solid lagging of small poles or boards was set outside the frames, as shown in the model, to provide absolute support of the ground. Details of the framing, the windlass, and all tools and appliances were supplied by Agricola, with no need for interpretation or interpolation.
The basic framing pattern of sill, side posts and cap piece, all morticed together, with lagging used where needed, was translated unaltered into tunneling practice, particularly in small exploratory drifts. It remained in this application until well into the 20th century.
The pressure exerted upon tunnels of large area was countered during construction by timbering systems of greater elaboration, evolved from the basic one. By the time that tunnels of section large enough to accommodate canals and railways were being undertaken as matter-of-course civil engineering works, a series of nationally distinguishable systems had emerged, each possessing characteristic points of favor and fault. As might be suspected, the English system of tunnel timbering, for instance, was rarely applied on the Continent, nor were the German, Austrian or Belgian systems normally seen in Great Britain. All were used at one time or another in this country, until the American system was introduced in about 1855. While the timbering commonly remained in place in mines, it would be followed up by permanent masonry arching and lining in tunnel work.
Overhead in the museum Hall of Civil Engineering are frames representing the English, Austrian and American systems. Nearby, a series of small relief models (fig. 19) is used to show the sequence of enlargement in a soft-ground railroad tunnel of about 1855, using the Austrian system. Temporary timber support of tunnels fell from use gradually after the advent of shield tunneling in conjunction with cast-iron lining. This formed a perfect support immediately behind the shield, as well as the permanent lining of the tunnel.
BRUNEL'S THAMES TUNNEL
The interior surfaces of tunnels through ground merely unstable are amenable to support by various systems of timbering and arching. This becomes less true as the fluidity of the ground increases. The soft material which normally comprises the beds of rivers can approach an almost liquid condition resulting in a hydraulic head from the overbearing water sufficient to prevent the driving of even the most carefully worked drift, supported by simple timbering. The basic defect of the timbering systems used in mining and tunneling was that there was inevitably a certain amount of the face or ceiling unsupported just previous to setting a frame, or placing over it the necessary section of lagging. In mine work, runny soil could, and did, break through such gaps, filling the working. For this reason, there were no serious attempts made before 1825 to drive subaqueous tunnels.
In that year, work was started on a tunnel under the Thames between the Rotherhithe and Wapping sections of London, under guidance of the already famous engineer Marc Isambard Brunel (1769-1849), father of I. K. Brunel. The undertaking is of great interest in that Brunel employed an entirely novel apparatus of his own invention to provide continuous and reliable support of the soft water-bearing clay which formed the riverbed. By means of this "shield," Brunel was able to drive the world's first subaqueous tunnel.[3]
The shield was of cast-iron, rectangular in elevation, and was propelled forward by jackscrews. Shelves at top, bottom, and sides supported the tunnel roof, floor, and walls until the permanent brick lining was placed. The working face, the critical area, was supported by a large number of small "breasting boards," held against the ground by small individual screws bearing against the shield framework. The shield itself was formed of 12 separate frames, each of which could be advanced independently of the others. The height was 22 feet 3 inches: the width 37 feet 6 inches.
The progress was piecemeal. In operation the miners would remove one breasting board at a time, excavate in front of it, and then replace it in the advanced position--about 6 inches forward. This was repeated with the next board above or below, and the sequence continued until the ground for the entire height of one of the 12 sections had been removed. The board screws for that section were shifted to bear on the adjacent frames, relieving the frame of longitudinal pressure. It could then be screwed forward by the amount of advance, the screws bearing to the rear on the completed masonry. Thus, step by step the tunnel progressed slowly, the greatest weekly advance being 14 feet.
In the left-hand portion of the model is the shaft sunk to begin operations; here also is shown the bucket hoist for removing the spoil. The V-type steam engine powering the hoist was designed by Brunel. At the right of the main model is an enlarged detail of the shield, actually an improved version built in 1835.
The work continued despite setbacks of every sort. The financial ones need no recounting here. Technically, although the shield principle proved workable, the support afforded was not infallible. Four or five times the river broke through the thin cover of silt and flooded the workings, despite the utmost caution in excavating. When this occurred, masses of clay, sandbags, and mats were dumped over the opening in the riverbed to seal it, and the tunnel pumped out. I. K. Brunel acted as superintendent and nearly lost his life on a number of occasions. After several suspensions of work resulting from withdrawal or exhaustion of support, one lasting seven years, the work was completed in 1843.
Despite the fact that Brunel had, for the first time, demonstrated a practical method for tunneling in firm and water-bearing ground, the enormous cost of the work and the almost overwhelming problems encountered had a discouraging effect rather than otherwise. Not for another quarter of a century was a similar project undertaken.
The Thames Tunnel was used for foot and light highway traffic until about 1870 when it was incorporated into the London Underground railway system, which it continues to serve today. The roofed-over top sections of the two shafts may still be seen from the river.
A number of contemporary popular accounts of the tunnel exist, but one of the most thorough and interesting expositions on a single tunnel work of any period is Henry Law's _A Memoir of the Thames Tunnel_, published in 1845-1846 by John Weale. Law, an eminent civil engineer, covers the work in incredible detail from its inception until the major suspension in late 1828 when slightly more than half completed. The most valuable aspect of his record is a series of plates of engineering drawings of the shield and its components, which, so far as is known, exist nowhere else. These formed the basis of the enlarged section of the shield, shown to the right of the model of the tunnel itself. A vertical section through the shield is reproduced here from Law for comparison with the model (figs. 21 and 23).
THE TOWER SUBWAY
Various inventors attempted to improve upon the Brunel shield, aware of the fundamental soundness of the shield principle. Almost all bypassed the rectangular sectional construction used in the Thames Tunnel, and took as a starting point a sectional shield of circular cross section, advanced by Brunel in his original patent of 1818. James Henry Greathead (1844-1896), rightfully called the father of modern subaqueous tunneling, surmised in later years that Brunel had chosen a rectangular configuration for actual use, as one better adapted to the sectional type of shield. The English civil engineer, Peter W. Barlow, in 1864 and 1868 patented a circular shield, of one piece, which was the basis of one used by him in constructing a small subway of 1350 feet beneath the Thames in 1869, the first work to follow the lead of Brunel. Greathead, acting as Barlow's contractor, was the designer of the shield actually used in the work, but it was obviously inspired by Barlow's patents.
The reduction of the multiplicity of parts in the Brunel shield to a single rigid unit was of immense advantage and an advance perhaps equal to the shield concept of tunneling itself. The Barlow-Greathead shield was like the cap of a telescope with a sharpened circular ring on the front to assist in penetrating the ground. The diaphragm functioned, as did Brunel's breasting boards, to resist the longitudinal earth pressure of the face, and the cylindrical portion behind the diaphragm bore the radial pressure of roof and walls. Here also for the first time, a permanent lining formed of cast-iron segments was used, a second major advancement in soft-ground tunneling practice. Not only could the segments be placed and bolted together far more rapidly than masonry lining could be laid up, but unlike the green masonry, they could immediately bear the full force of the shield-propelling screws.
Barlow, capitalizing on Brunel's error in burrowing so close to the riverbed, maintained an average cover of 30 feet over the tunnel, driving through a solid stratum of firm London clay which was virtually impervious to water. As the result of this, combined with the advantages of the solid shield and the rapidly placed iron lining, the work moved forward at a pace and with a facility in startling contrast to that of the Thames Tunnel, although in fairness it must be recalled that the face area was far less.
The clay was found sufficiently sound that it could be readily excavated without the support of the diaphragm, and normally three miners worked in front of the shield, digging out the clay and passing it back through a doorway in the plate. This could be closed in case of a sudden settlement or break in. Following excavation, the shield was advanced 18 inches into the excavated area by means of 6 screws, and a ring of lining segments 18 inches in length bolted to the previous ring under cover of the overlapping rear skirt of the shield. The small annular space left between the outside of the lining and the clay by the thickness and clearance of the skirt--about an inch--was filled with thin cement grout. The tunnel was advanced 18 inches during each 8-hour shift. The work continued around the clock, and the 900-foot river section was completed in only 14 weeks.[4] The entire work was completed almost without incident in just under a year, a remarkable performance for the world's second subaqueous tunnel.
The Tower Subway at first operated with cylindrical cars that nearly filled the 7-foot bore; the cars were drawn by cables powered by small steam engines in the shafts. This mode of power had previously been used in passenger service only on the Greenwich Street elevated railway in New York. Later the cars were abandoned as unprofitable and the tunnel turned into a footway (fig. 32). This small tunnel, the successful driving due entirely to Greathead's skill, was the forerunner of the modern subaqueous tunnel. In it, two of the three elements essential to such work thereafter were first applied: the one-piece movable shield of circular section, and the segmental cast-iron lining.
The documentation of this work is far thinner than for the Thames Tunnel. The most accurate source of technical information is a brief historical account in Copperthwaite's classic _Tunnel Shields and the Use of Compressed Air in Subaqueous Works_, published in 1906. Copperthwaite, a successful tunnel engineer, laments the fact that he was able to turn up no drawing or original data on this first shield of Greathead's, but he presents a sketch of it prepared in the Greathead office in 1895, which is presumably a fair representation (fig. 33). The Tower Subway model was built on the basis of this and several woodcuts of the working area that appeared contemporaneously in the illustrated press. In this and the adjacent model of Beach's Broadway Subway, the tunnel axis has been placed on an angle to the viewer, projecting the bore into the case so that the complete circle of the working face is included for a more suggestive effect. This was possible because of the short length of the work included.
Henry S. Drinker, also a tunnel engineer and author of the most comprehensive work on tunneling ever published, treats rock tunneling in exhaustive detail up to 1878. His notice of what he terms "submarine tunneling" is extremely brief. He does, however, draw a most interesting comparison between the first Thames Tunnel, built by Brunel, and the second, built by Greathead 26 years later:
FIRST THAMES TUNNEL SECOND THAMES TUNNEL (TOWER SUBWAY)
Brickwork lining, 38 feet Cast-iron lining of 8 feet wide by 22-1/2 feet high. outside diameter.
120-ton cast-iron shield, 2-1/2-ton, wrought-iron shield, accommodating 36 miners. accommodating at most 3 men.
Workings filled by irruption "Water encountered at almost of river five times. any time could have been gathered in a stable pail."
Eighteen years elapsed between Work completed in about start and finish of work. eleven months.
Cost: $3,000,000. Cost: $100,000.
BEACH'S BROADWAY SUBWAY
Almost simultaneously with the construction of the Tower Subway, the first American shield tunnel was driven by Alfred Ely Beach (1826-1896). Beach, as editor of the _Scientific American_ and inventor of, among other things, a successful typewriter as early as 1856, was well known and respected in technical circles. He was not a civil engineer, but had become concerned with New York's pressing traffic problem (even then) and as a solution, developed plans for a rapid-transit subway to extend the length of Broadway. He invented a shield as an adjunct to this system, solely to permit driving of the tunnel without disturbing the overlying streets.
An active patent attorney as well, Beach must certainly have known of and studied the existing patents for tunneling shields, which were, without exception, British. In certain aspects his shield resembled the one patented by Barlow in 1864, but never built. However, work on the Beach tunnel started in 1869, so close in time to that on the Tower Subway, that it is unlikely that there was any influence from that source. Beach had himself patented a shield, in June 1869, a two-piece, sectional design that bore no resemblance to the one used. His subway plan had been first introduced at the 1867 fair of the American Institute in the form of a short plywood tube through which a small, close-fitting car was blown by a fan. The car carried 12 passengers. Sensing opposition to the subway scheme from Tammany, in 1868 Beach obtained a charter to place a small tube beneath Broadway for transporting mail and small packages pneumatically, a plan he advocated independently of the passenger subway.
Under this thin pretense of legal authorization, the sub-rosa excavation began from the basement of a clothing store on Warren Street near Broadway. The 8-foot-diameter tunnel ran eastward a short distance, made a 90-degree turn, and thence southward under Broadway to stop a block away under the south side of Murray Street. The total distance was about 312 feet. Work was carried on at night in total secrecy, the actual tunneling taking 58 nights. At the Warren Street terminal, a waiting room was excavated and a large Roots blower installed for propulsion of the single passenger car. The plan was similar to that used with the model in 1867: the cylindrical car fitted the circular tunnel with only slight circumferential clearance. The blower created a plenum within the waiting room and tunnel area behind the car of about 0.25 pounds per square inch, resulting in a thrust on the car of almost a ton, not accounting for blowby. The car was thus blown along its course, and was returned by reversing the blower's suction and discharge ducts to produce an equivalent vacuum within the tunnel.
The system opened in February of 1870 and remained in operation for about a year. Beach was ultimately subdued by the hostile influences of Boss Tweed, and the project was completely abandoned. Within a very few more years the first commercially operated elevated line was built, but the subway did not achieve legitimate status in New York until the opening of the Interborough line in 1904. Ironically, its route traversed Broadway for almost the length of the island.
The Beach shield operated with perfect success in this brief trial, although the loose sandy soil encountered was admittedly not a severe test of its qualities. No diaphragm was used; instead a series of 8 horizontal shelves with sharpened leading edges extended across the front opening of the shield. The outstanding feature of the machine was the substitution for the propelling screws used by Brunel and Greathead of 18 hydraulic rams, set around its circumference. These were fed by a single hand-operated pump, seen in the center of figure 34. By this means the course of the shield's forward movement could be controlled with a convenience and precision not attainable with screws. Vertical and horizontal deflection was achieved by throttling the supply of water to certain of the rams, which could be individually controlled, causing greater pressure on one portion of the shield than another. This system has not changed in the ensuing time, except, of course, in the substitution of mechanically produced hydraulic pressure for hand.
Unlike the driving of the Tower Subway, no excavation was done in front of the shield. Rather, the shield was forced by the rams into the soil for the length of their stroke, the material which entered being supported by the shelves. This was removed from the shelves and hauled off. The ram plungers then were withdrawn and a 16-inch length of the permanent lining built up within the shelter of the shield's tail ring. Against this, the rams bore for the next advance. Masonry lining was used in the straight section; cast-iron in the curved. The juncture is shown in the model.
Enlarged versions of the Beach shield were used in a few tunnels in the Midwest in the early 1870's, but from then until 1886 the shield method, for no clear reason, again entered a period of disuse finding no application on either side of the Atlantic despite its virtually unqualified proof at the hands of Greathead and Beach. Little precise information remains on this work. The Beach system of pneumatic transit is described fully in a well-illustrated booklet published by him in January 1868, in which the American Institute model is shown, and many projected systems of pneumatic propulsion as well as of subterranean and subaqueous tunneling described. Beach again (presumably) is author of the sole contemporary account of the Broadway Subway, which appeared in _Scientific American_ following its opening early in 1870. Included are good views of the tunnel and car, of the shield in operation, and, most important, a vertical sectional view through the shield (fig. 35).
It is interesting to note that optical surveys for maintenance of the course apparently were not used. The article illustrated and described the driving each night of a jointed iron rod up through the tunnel roof to the street, twenty or so feet above, for "testing the position."
THE FIRST HUDSON RIVER TUNNEL
Despite the ultimate success of Brunel's Thames Tunnel in 1843, the shield in that case afforded only moderately reliable protection because of the fluidity of the soil driven through, and its tendency to enter the works through the smallest opening in the shield's defense. An English doctor who had made physiological studies of the effects on workmen of the high air pressure within diving bells is said to have recommended to Brunel in 1828 that he introduce an atmosphere of compressed air into the tunnel to exclude the water and support the work face.
This plan was first formally described by Sir Thomas Cochrane (1775-1860) in a British patent of 1830. Conscious of Brunel's problems, he proposed a system of shaft sinking, mining, and tunneling in water-bearing materials by filling the excavated area with air sufficiently above atmospheric pressure to prevent the water from entering and to support the earth. In this, and his description of air locks for passage of men and materials between the atmosphere and the pressurized area, Cochrane fully outlined the essential features of pneumatic excavation as developed since.
In 1839, a French engineer first used the system in sinking a mine shaft through a watery stratum. From then on, the sinking of shafts, and somewhat later the construction of bridge pier foundations, by the pneumatic method became almost commonplace engineering practice in Europe and America. Not until 1879 however, was the system tried in tunneling work, and then, as with the shield ten years earlier, almost simultaneously here and abroad. The first application was in a small river tunnel in Antwerp, only 5 feet in height. This project was successfully completed relying on compressed air alone to support the earth, no shield being used. The importance of the work cannot be considered great due to its lack of scope.
In 1871 Dewitt C. Haskin (1822-1900), a west coast mine and railroad builder, became interested in the pneumatic caissons then being used to found the river piers of Eads' Mississippi River bridge at St. Louis. In apparent total ignorance of the Cochrane patent, he evolved a similar system for tunneling water-bearing media, and in 1873 proposed construction of a tunnel through the silt beneath the Hudson to provide rail connection between New Jersey and New York City.
It would be difficult to imagine a site more in need of such communication. All lines from the south terminated along the west shore of the river and the immense traffic--cars, freight and passengers--was carried across to Manhattan Island by ferry and barge with staggering inconvenience and at enormous cost. A bridge would have been, and still is, almost out of the question due not only to the width of the crossing, but to the flatness of both banks. To provide sufficient navigational clearance (without a drawspan), impracticably long approaches would have been necessary to obtain a permissibly gentle grade.
Haskin formed a tunneling company and began work with the sinking of a shaft in Hoboken on the New Jersey side. In a month it was halted because of an injunction by, curiously, the D L & W Railroad, who feared for their vast investment in terminal and marine facilities. Not until November of 1879 was the injunction lifted and work again commenced. The shaft was completed and an air lock located in one wall from which the tunnel proper was to be carried forward. It was Haskin's plan to use no shield, relying solely on the pressure of compressed air to maintain the work faces and prevent the entry of water. The air was admitted in late December, and the first large-scale pneumatic tunneling operation launched. A single 26-foot, double-track bore was at first undertaken, but a work face of such diameter proved unmanageable and two oval tubes 18 feet high by 16 feet wide were substituted, each to carry a single track. Work went forward with reasonable facility, considering the lack of precedent. A temporary entrance was formed of sheet-iron rings from the air lock down to the tunnel grade, at which point the permanent work of the north tube was started. Immediately behind the excavation at the face, a lining of thin wrought-iron plates was built up, to provide form for the 2-foot, permanent brick lining that followed. The three stages are shown in the model in about their proper relationship of progress. The work is shown passing beneath an old timber-crib bulkhead, used for stabilizing the shoreline.
The silt of the riverbed was about the consistency of putty and under good conditions formed a secure barrier between the excavation and the river above. It was easily excavated, and for removal was mixed with water and blown out through a pipe into the shaft by the higher pressure in the tunnel. About half was left in the bore for removal later. The basic scheme was workable, but in operation an extreme precision was required in regulating the air pressure in the work area.[5] It was soon found that there existed an 11-psi difference between the pressure of water on the top and the bottom of the working face, due to the 22-foot height of the unlined opening. Thus, it was impossible to maintain perfect pneumatic balance of the external pressure over the entire face. It was necessary to strike an average with the result that some water entered at the bottom of the face where the water pressure was greatest, and some air leaked out at the top where the water pressure was below the air pressure. Constant attention was essential: several men did nothing but watch the behavior of the leaks and adjusted the pressure as the ground density changed with advance. Air was supplied by several steam-driven compressors at the surface.
The air lock permitted passage back and forth of men and supplies between the atmosphere and the work area, without disturbing the pressure differential. This principle is demonstrated by an animated model set into the main model, to the left of the shaft (fig. 39). The variation of pressure within the lock chamber to match the atmosphere or the pressurized area, depending on the direction of passage, is clearly shown by simplified valves and gauges, and by the use of light in varying color density. In the Haskin tunnel, 5 to 10 minutes were taken to pass the miners through the lock so as to avoid too abrupt a physiological change.
Despite caution, a blowout occurred in July 1880 due to air leakage not at the face, but around the temporary entrance. One door of the air lock jammed and twenty men drowned, resulting in an inquiry which brought forth much of the distrust with which Haskin was regarded by the engineering profession. His ability and qualifications were subjected to the bitterest attack in and by the technical press. There is some indication that, although the project began with a staff of competent engineers, they were alienated by Haskin in the course of work and at least one withdrew. Haskin's remarks in his own defense indicate that some of the denunciation was undoubtedly justified. And yet, despite this reaction, the fundamental merit of the pneumatic tunneling method had been demonstrated by Haskin and was immediately recognized and freely acknowledged. It was apparent at the same time, however, that air by itself did not provide a sufficiently reliable support for large-area tunnel works in unstable ground, and this remains the only major subaqueous tunnel work driven with air alone.
After the accident, work continued under Haskin until 1882 when funds ran out. About 1600 feet of the north tube and 600 feet of the south tube had been completed. Greathead resumed operations with a shield for a British company in 1889, but exhaustion of funds again caused stoppage in 1891. The tunnel was finally completed in 1904, and is now in use as part of the Hudson and Manhattan rapid-transit system, never providing the sought-after rail link. A splendid document of the Haskin portion of the work is S. D. V. Burr's _Tunneling Under the Hudson River_ published in 1885. It is based entirely upon firsthand material and contains drawings of most of the work, including the auxiliary apparatus. It is interesting to note that electric illumination (arc, not incandescent, lights) and telephones were used, unquestionably the first employment of either in tunnel work.
THE ST. CLAIR TUNNEL
The final model of the soft-ground series reflects, as did the Hoosac Tunnel model for hard-rock tunneling, final emergence into the modern period. Although the St. Clair Tunnel was completed over 70 years ago, it typifies in its method of construction, the basic procedures of subaqueous work in the present day. The Thames Tunnel of Brunel, and Haskin's efforts beneath the Hudson, had clearly shown that by themselves, both the shield and pneumatic systems of driving through fluid ground were defective in practice for tunnels of large area. Note that the earliest successful works by each method had been of very small area, so that the influence of adverse conditions was greatly diminished.
The first man to perceive and seize upon the benefits to be gained by combining the two systems was, most fittingly, Greathead. Although he had projected the technique earlier, in driving the underground City and South London Railway in 1886, he brought together for the first time the three fundamental elements essential for the practical tunneling of soft, water-bearing ground: compressed-air support of the work during construction, the movable shield, and cast-iron, permanent lining. The marriage was a happy one indeed; the limitations of each system were almost perfectly overcome by the qualities of the others.
The conditions prevailing in 1882 at the Sarnia, Ontario, terminal of the Grand Trunk Railway, both operational and physical, were almost precisely the same as those which inspired the undertaking of the Hudson River Tunnel. The heavy traffic at this vital U.S.--Canada rail interchange was ferried inconveniently across the wide St. Clair River, and the bank and river conditions precluded construction of a bridge. A tunnel was projected by the railway in that year, the time when Haskin's tribulations were at their height. Perhaps because of this lack of precedent for a work of such size, nothing was done immediately. In 1884 the railway organized a tunnel company; in 1886 test borings were made in the riverbed and small exploratory drifts were started across from both banks by normal methods of mine timbering. The natural gas, quicksand, and water encountered soon stopped the work.
It was at this time that the railway's president visited Greathead's City and South London workings. The obvious answer to the St. Clair problem lay in the successful conduct of this subway. Joseph Hobson, chief engineer of the Grand Trunk and of the tunnel project, in designing a shield, is said to have searched for drawings of the shields used in the Broadway and Tower Subways of 1868-9, but unable to locate any, he relied to a limited extent on the small drawings of those in Drinker's volume. There is no explanation as to why he did not have drawings of the City and South London shield at that moment in use, unless one considers the rather unlikely possibility that Greathead maintained its design in secrecy.
The Hobson shield followed Greathead's as closely as any other, in having a diaphragm with closable doors, but a modification of Beach's sharpened horizontal shelves was also used. However, these functioned more as working platforms than supports for the earth. The machine was 21-1/2 feet in diameter, an unprecedented size and almost twice that of Greathead's current one. It was driven by 24 hydraulic rams. Throughout the entire preliminary consideration of the project there was a marked sense of caution that amounted to what seems an almost total lack of confidence in success. Commencement of the work from vertical shafts was planned so that if the tunnel itself failed, no expenditure would have been made for approach work. In April 1888, the shafts were started near both riverbanks, but before reaching proper depth the almost fluid clay and silt flowed up faster than it could be excavated and this plan was abandoned. After this second inauspicious start, long open approach cuts were made and the work finally began. The portals were established in the cuts, several thousand feet back from each bank and there the tunneling itself began. The portions under the shore were driven without air. When the banks were reached, brick bulkheads containing air locks were built across the opening and the section beneath the river, about 3,710 feet long, driven under air pressure of 10 to 28 pounds above atmosphere. For most of the way, the clay was firm and there was little air leakage. It was found that horses could not survive in the compressed air, and so mules were used under the river.
In the firm clay, excavation was carried on several feet in front of the shield, as shown in the model (fig. 42). About twelve miners worked at the face. However, in certain strata the clay encountered was so fluid that the shield could be simply driven forward by the rams, causing the muck to flow in at the door openings without excavation. After each advance, the rams were retracted and a ring of iron lining segments built up, as in the Tower Subway. Here, for the first time, an "erector arm" was used for placing the segments, which weighed about half a ton. In all respects, the work advanced with wonderful facility and lack of operational difficulty. Considering the large area, no subaqueous tunnel had ever been driven with such speed. The average monthly progress for the American and Canadian headings totaled 455 feet, and at top efficiency 10 rings or a length of 15.3 feet could be set in a 24-hour day in each heading. The 6,000 feet of tunnel was driven in just a year; the two shields met vis-a-vis in August of 1890.
The transition was complete. The work had been closely followed by the technical journals and the reports of its successful accomplishment thus were brought to the attention of the entire civil engineering profession. As the first major subaqueous tunnel completed in America and the first in the world of a size able to accommodate full-scale rail traffic, the St. Clair Tunnel served to dispel the doubts surrounding such work, and established the pattern for a mode of tunneling which has since changed only in matters of detail.
Of the eight models, only this one was built under the positive guidance of original documents. In the possession of the Canadian National Railways are drawings not only of all elements of the shield and lining, but of much of the auxiliary apparatus used in construction. Such materials rarely survive, and do so in this case only because of the foresight of the railway which, to avoid paying a high profit margin to a private contractor as compensation for the risk and uncertainty involved, carried the contract itself and, therefore, preserved all original drawing records.
While the engineering of tunnels has been comprehensively treated in this paper from the historical standpoint, it is well to still reflect that the advances made in tunneling have not perceptibly removed the elements of uncertainty but have only provided more positive and effective means of countering their forces. Still to be faced are the surprises of hidden streams, geologic faults, shifts of strata, unstable materials, and areas of extreme pressure and temperature.
BIBLIOGRAPHY
AGRICOLA, GEORGIUS. _De re Metallica._ [English transl. H. C. and L. H. Hoover (_The Mining Magazine_, London, 1912).] Basel: Froben, 1556.
BEACH, ALFRED ELY. _The pneumatic dispatch._ New York: The American News Company, 1868.
BEAMISH, RICHARD. _A memoir of the life of Sir Marc Isambard Brunel._ London: Longmans, Green, Longmans and Roberts, 1862.
BURR, S. D. V. _Tunneling under the Hudson River._ New York: John Wiley and Sons, 1885.
COPPERTHWAITE, WILLIAM CHARLES. _Tunnel shields and the use of compressed air in subaqueous works._ New York: D. Van Nostrand Company, 1906.
DRINKER, HENRY STURGESS. _Tunneling, explosive compounds and rock drills._ New York: John Wiley and Sons, 1878.
LATROBE, BENJAMIN H. Report on the Hoosac Tunnel (Baltimore, October 1, 1862). Pp. 125-139, app. 2, in _Report of the commissioners upon the Troy and Greenfield Railroad and Hoosac Tunnel_. Boston, 1863.
LAW, HENRY. A memoir of the Thames Tunnel. _Weale's Quarterly Papers on Engineering_ (London, 1845-46), vol. 3, pp. 1-25 and vol. 5, pp. 1-86.
The pneumatic tunnel under Broadway, N.Y. _Scientific American_ (March 5, 1870), pp. 154-156.
_Report of the commissioners upon the Troy and Greenfield Railroad and Hoosac Tunnel to his excellency the governor and the honorable the executive council of the state of Massachusetts, February 28, 1863._ Boston, 1863.
STORROW, CHARLES S. Report on European tunnels (Boston, November 28, 1862). Pp. 5-122, app. 1, in _Report of the commissioners upon the Troy and Greenfield Railroad and Hoosac Tunnel...._ Boston, 1863.
The St. Clair Tunnel. _Engineering News_ (in series running October 4 to December 27, 1890).
FOOTNOTES
[1] There are two important secondary techniques for opening subterranean and subaqueous ways, neither a method truly of tunneling. One of these, of ancient origin, used mainly in the construction of shallow subways and utility ways, is the "cut and cover" system, whereby an open trench is excavated and then roofed over. The result is, in effect, a tunnel. The concept of the other method was propounded in the early 19th century but only used practically in recent years. This is the "trench" method, a sort of subaqueous equivalent of cut and cover. A trench is dredged in the bed of a body of water, into which prefabricated sections of large diameter tube are lowered, in a continuous line. The joints are then sealed by divers, the trench is backfilled over the tube, the ends are brought up to dryland portals, the water is pumped out, and a subterranean passage results. The Chesapeake Bay Bridge Tunnel (1960-1964) is a recent major work of this character.
[2] In 1952 a successful machine was developed on this plan, with hardened rollers on a revolving cutting head for disintegrating the rock. The idea is basically sound, possessing advantages in certain situations over conventional drilling and blasting systems.
[3] In 1807 the noted Cornish engineer Trevithick commenced a small timbered drift beneath the Thames, 5 feet by 3 feet, as an exploratory passage for a larger vehicular tunnel. Due to the small frontal area, he was able to successfully probe about 1000 feet, but the river then broke in and halted the work. Mine tunnels had also reached beneath the Irish Sea and various rivers in the coal regions of Newcastle, but these were so far below the surface as to be in perfectly solid ground and can hardly be considered subaqueous workings.
[4] Unlike the Brunel tunnel, this was driven from both ends simultaneously, the total overall progress thus being 3 feet per shift rather than 18 inches. A top speed of 9 feet per day could be advanced by each shield under ideal conditions.
[5] Ideally, the pressure of air within the work area of a pneumatically driven tunnel should just balance the hydrostatic head of the water without, which is a function of its total height above the opening. If the air pressure is not high enough, water will, of course, enter, and if very low, there is danger of complete collapse of the unsupported ground areas. If too high, the air pressure will overcome that due to the water and the air will force its way out through the ground, through increasingly larger openings, until it all rushes out suddenly in a "blowout." The pressurized atmosphere gone, the water then is able to pour in through the same opening, flooding the workings.
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CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY:
PAPER 42
THE "PIONEER": LIGHT PASSENGER LOCOMOTIVE OF 1851 IN THE MUSEUM OF HISTORY AND TECHNOLOGY
_John H. White_
THE CUMBERLAND VALLEY RAILROAD 244
SERVICE HISTORY OF THE "PIONEER" 249
MECHANICAL DESCRIPTION OF THE "PIONEER" 251
FOOTNOTES
_John H. White_
The "PIONEER": LIGHT PASSENGER LOCOMOTIVE of 1851 _In the Museum of History and Technology_
_In the mid-nineteenth century there was a renewed interest in the light, single-axle locomotives which were proving so very successful for passenger traffic. These engines were built in limited number by nearly every well-known maker, and among the few remaining is the 6-wheel "Pioneer," on display in the Museum of History and Technology, Smithsonian Institution. This locomotive is a true representation of a light passenger locomotive of 1851 and a historic relic of the mid-nineteenth century._
THE AUTHOR: _John H. White is associate curator of transportation in the Smithsonian Institution's Museum of History and Technology._
The "PIONEER" is an unusual locomotive and on first inspection would seem to be imperfect for service on an American railroad of the 1850's. This locomotive has only one pair of driving wheels and no truck, an arrangement which marks it as very different from the highly successful standard 8-wheel engine of this period. All six wheels of the _Pioneer_ are rigidly attached to the frame. It is only half the size of an 8-wheel engine of 1851 and about the same size of the 4--2--0 so common in this country some 20 years earlier. Its general arrangement is that of the rigid English locomotive which had, years earlier, proven unsuitable for use on U.S. railroads.
These objections are more apparent than real, for the _Pioneer_, and other engines of the same design, proved eminently successful when used in the service for which they were built, that of light passenger traffic. The _Pioneer's_ rigid wheelbase is no problem, for when it is compared to that of an 8-wheel engine it is found to be about four feet less; and its small size is no problem when we realize it was not intended for heavy service. Figure 2, a diagram, is a comparison of the _Pioneer_ and a standard 8-wheel locomotive.
Since the service life of the _Pioneer_ was spent on the Cumberland Valley Railroad, a brief account of that line is necessary to an understanding of the service history of this locomotive.
_Exhibits of the "Pioneer"_
The _Pioneer_ has been a historic relic since 1901. In the fall of that year minor repairs were made to the locomotive so that it might be used in the sesquicentennial celebration at Carlisle, Pennsylvania. On October 22, 1901, the engine was ready for service, but as it neared Carlisle a copper flue burst. The fire was extinguished and the _Pioneer_ was pushed into town by another engine. In the twentieth century, the _Pioneer_ was displayed at the Louisiana Purchase Exposition, St. Louis, Missouri, in 1904, and at the Wheeling, West Virginia, semicentennial in 1913. In 1927 it joined many other historic locomotives at the Baltimore and Ohio Railroad's "Fair of the Iron Horse" which commemorated the first one hundred years of that company. From about 1913 to 1925 the _Pioneer_ also appeared a number of times at the Apple-blossom Festival at Winchester, Virginia. In 1933-1934 it was displayed at the World's Fair in Chicago, and in 1948 at the Railroad Fair in the same city. Between 1934 and March 1947 it was exhibited at the Franklin Institute, Philadelphia, Pennsylvania.
The Cumberland Valley Railroad
The Cumberland Valley Railroad (C.V.R.R.) was chartered on April 2, 1831, to connect the Susquehanna and Potomac Rivers by a railroad through the Cumberland Valley in south-central Pennsylvania. The Cumberland Valley, with its rich farmland and iron-ore deposits, was a natural north-south route long used as a portage between these two rivers. Construction began in 1836, and because of the level valley some 52 miles of line was completed between Harrisburg and Chambersburg by November 16, 1837. In 1860, by way of the Franklin Railroad, the line extended to Hagerstown, Maryland. It was not until 1871 that the Cumberland Valley Railroad reached its projected southern terminus, the Potomac River, by extending to Powells Bend, Maryland. Winchester, Virginia, was entered in 1890 giving the Cumberland Valley Railroad about 165 miles of line. The railroad which had become associated with the Pennsylvania Railroad in 1859, was merged with that company in 1919.
By 1849 the Cumberland Valley Railroad was in poor condition; the strap-rail track was worn out and new locomotives were needed. Captain Daniel Tyler was hired to supervise rebuilding the line with T-rail, and easy grades and curves. Tyler recommended that a young friend of his, Alba F. Smith, be put in charge of modernizing and acquiring new equipment. Smith recommended to the railroad's Board of Managers on June 25, 1851, that "much lighter engines than those now in use may be substituted for the passenger transportation and thereby effect a great saving both in point of fuel and road repairs...."[1] Smith may well have gone on to explain that the road was operating 3- and 4-car passenger trains with a locomotive weighing about 20 tons; the total weight was about 75 tons, equalling the uneconomical deadweight of 1200 pounds per passenger. Since speed was not an important consideration (30 mph being a good average), the use of lighter engines would improve the deadweight-to-passenger ratio and would not result in a slower schedule.
The Board of Managers agreed with Smith's recommendations and instructed him "... to examine the two locomotives lately built by Mr. Wilmarth and now in the [protection?] of Captain Tyler at Norwich and if in his judgment they are adequate to our wants ... have them forwarded to the road."[2] Smith inspected the locomotives not long after this resolution was passed, for they were on the road by the time he made the following report[3] to the Board on September 24, 1851:
In accordance with a resolution passed at the last meeting of your body relative to the small engines built by Mr. Wilmarth I proceeded to Norwich to make trial of their capacity--fitness or suitability to the Passenger transportation of our Road--and after as thorough a trial as circumstances would admit (being on another Road than our own) I became satisfied that with some necessary improvements which would not be expensive (and are now being made at our shop) the engines would do the business of our Road not only in a manner satisfactory in point of speed and certainty but with greater ultimate economy in Expenses than has before been practised in this Country.
_Columbia_
Hudson River Railroad Lowell Machine Shop, 1852 Wt. 27-1/2 tons (engine only) Cyl. 16-1/2 x 22 inches Wheel diam. 84 inches
_Pioneer_
Cumberland Valley Railroad Seth Wilmarth, 1851 12-1/2 tons 8-1/2 x 14 inches 54 inches
After making the above trial of the Engines--I stated to your Hon. President the result of the trial--with my opinion of their Capacity to carry our passenger trains at the speed required which was decidedly in favor of the ability of the Engines. He accordingly agreed that the Engines should at once be forwarded to the Road in compliance with the Resolution of your Board. I immediately ordered the Engines shipped at the most favorable rates. They came to our Road safely in the Condition in which they were shipped. One of the Engines has been placed on the Road and I believe performed in such a manner as to convince all who are able to judge of this ability to perform--although the maximum duty of the Engines was not performed on account of some original defects which are now being remedied as I before stated.
Within ten days the Engine will be able to run regularly with a train on the Road where in shall be enabled to judge correctly of their merits.
An accident occurred during the trial of the Small Engine at Norwich which caused a damage of about $300 in which condition the Engine came here and is now being repaired--the cost of which will be presented to your Board hereafter. As to the fault or blame of parties connected with the accident as also the question of responsibility for Repairs are questions for your disposal. I therefore leave the matter until further called upon.
The Expenses necessarily incurred by the trial of the Engines and also the Expenses of transporting the same are not included in the Statement herewith presented, the whole amount of which will not probably exceed $400.00.
These two locomotives became the Cumberland Valley Railroad's _Pioneer_ (number 13) and _Jenny Lind_ (number 14). While Smith notes that one of the engines was damaged during the inspection trials, Joseph Winters, an employee of the Cumberland Valley who claimed he was accompanying the engine enroute to Chambersburg at the time of their delivery, later recalled that both engines were damaged in transit.[4] According to Winters a train ran into the rear of the _Jenny Lind_, damaging both it and the _Pioneer_, the accident occurring near Middletown, Pennsylvania. The _Jenny Lind_ was repaired at Harrisburg but the _Pioneer_, less seriously damaged, was taken for repairs to the main shops of the Cumberland Valley road at Chambersburg.
While there seems little question that these locomotives were not built as a direct order for the Cumberland Valley Railroad, an article[5] appearing in the _Railroad Advocate_ in 1855 credits their design to Smith. The article speaks of a 2--2--4 built for the Macon and Western Railroad and says in part:
This engine is designed and built very generally upon the ideas, embodied in some small tank engines designed by A. F. Smith, Esq., for the Cumberland Valley road. Mr. Smith is a strong advocate of light engines, and his novel style and proportions of engines, as built for him a few years since, by Seth Wilmarth, at Boston, are known to some of our readers. Without knowing all the circumstances under which these engines are worked on the Cumberland Valley road, we should not venture to repeat all that we have heard of their performances, it is enough to say that they are said to do more, in proportion to their weight, than any other engines now in use.
The author believes that the _Railroad Advocate's_ claim of Smith's design of the _Pioneer_ has been confused with his design of the _Utility_ (figs. 6, 7). Smith designed this compensating-lever engine to haul trains over the C.V.R.R. bridge at Harrisburg. It was built by Wilmarth in 1854.
According to statements of Smith and the Board of Managers quoted on page 244, the _Pioneer_ and the _Jenny Lind_ were not new when purchased from their maker, Seth Wilmarth. Although of recent manufacture, previous to June 1851, they were apparently doing service on a road in Norwich, Connecticut. It should be mentioned that both Smith and Tyler were formerly associated with the Norwich and Worcester Railroad and they probably learned of these two engines through this former association. It is possible that the engines were purchased from Wilmarth by the Cumberland Valley road, which had bought several other locomotives from Wilmarth in previous years. It was the practice of at least one other New England engine builder, the Taunton Locomotive Works, to manufacture engines on the speculation that a buyer would be found; if no immediate buyers appeared the engine was leased to a local road until a sale was made.[6]
Regarding the _Jenny Lind_ and _Pioneer_, Smith reported[7] to the Board of Managers at their meeting of March 17, 1852:
The small tank engines which were purchased last year ... and which I spoke in a former report as undergoing at that time some necessary improvements have since that time been fairly tested as to their capacity to run our passenger trains and proved to be equal to the duty.
The improvements proposed to be made have been completed only on one engine [_Jenny Lind_] which is now running regularly with passenger trains--the cost of repairs and improvements on this engine (this being the one accidentally broken on the trial) amounted to $476.51. The other engine is now in the shop, not yet ready for service but will be at an early day.
The _Pioneer_ and _Jenny Lind_ achieved such success in action that the president of the road, Frederick Watts, commented on their performance in the annual report of the Cumberland Valley Railroad for 1851. Watts stated that since their passenger trains were rarely more than a baggage car and two coaches, the light locomotives "... have been found to be admirably adapted to our business." The Cumberland Valley Railroad, therefore, added two more locomotives of similar design in the next few years. These engines were the _Boston_ and the _Enterprise_, also built by Wilmarth in 1854-1855.
Watts reported the _Pioneer_ and _Jenny Lind_ cost $7,642. A standard 8-wheel engine cost about $6,500 to $8,000 each during this period. In recent years, the Pennsylvania Railroad has stated the _Pioneer_ cost $6,200 in gold, but is unable to give the source for this information. The author can discount this statement for it does not seem reasonable that a light, cheap engine of the pattern of the _Pioneer_ could cost as much as a machine nearly twice its size.
Service History of the _Pioneer_
After being put in service, the _Pioneer_ continued to perform well and was credited as able to move a 4-car passenger train along smartly at 40 mph.[8] This tranquility was shattered in October 1862 by a raiding party led by Confederate General J. E. B. Stuart which burned the Chambersburg shops of the Cumberland Valley Railroad. The _Pioneer_, _Jenny Lind_, and _Utility_ were partially destroyed. The Cumberland Valley Railroad in its report for 1862 stated:
The Wood-shop, Machine-shop, Black-smith-shop, Engine-house, Wood-sheds, and Passenger Depot were totally consumed, and with the Engine-house three second-class Engines were much injured by the fire, but not so destroyed but that they may be restored to usefulness.
However, no record can be found of the extent or exact nature of the damage. The shops and a number of cars were burned so it is reasonable to assume that the cab and other wooden parts of the locomotive were damaged. One unverified report in the files of the Pennsylvania Railroad states that part of the roof and brick wall fell on the _Pioneer_ during the fire causing considerable damage. In June 1864 the Chambersburg shops were again burned by the Confederates, but on this occasion the railroad managed to remove all its locomotives before the raid. During the Civil War, the Cumberland Valley Railroad was obliged to operate longer passenger trains to satisfy the enlarged traffic. The _Pioneer_ and its sister single-axle engines were found too light for these trains and were used only on work and special trains. Reference to table 1 will show that the mileage of the _Pioneer_ fell off sharply for the years 1860-1865.
TABLE 1.--YEARLY MILEAGE OF THE PIONEER
(From Annual Reports of the Cumberland Valley Railroad)
_Year_: _Miles_
1852 3,182[a] 1853 20,722[b] 1854 18,087 1855 14,151 1856 20,998 1857 22,779 1858 29,094 1859 29,571 1860 4,824 1861 4,346 1862 ([c]) 1863 5,339 1864 224 1865 2,215 1866 20,546 1867 5,709 1868 13,626 1869 1,372 1870 ... 1871 2,102 1872 4,002 1873 3,721 1874 3,466 1875 636 1876 870 1877 406 1878 4,433 1879 ... 1880 8,306 1881 ([d]) --------- Total 244,727[e]
FOOTNOTES TO TABLE 1:
[a] Mileage 1852 for January to September (no record of mileage recorded in Annual Reports previous to 1852).
[b] 15,000 to 20,000 miles per year was considered very high mileage for a locomotive of the 1850's.
[c] No mileage reported for any engines due to fire.
[d] Not listed on roster.
[e] The Pennsylvania Railroad claims a total mileage of 255,675. This may be accounted for by records of mileages for 1862, 1870, and 1879.
In 1871 the _Pioneer_ was remodeled by A. S. Hull, master mechanic of the railroad. The exact nature of the alterations cannot be determined, as no drawings or photographs of the engine previous to this time are known to exist. In fact, the drawing (fig. 8) prepared by Hull in 1876 to show the engine as remodeled in 1871 is the oldest known illustration of the _Pioneer_. Paul Westhaeffer, a lifelong student of Cumberland Valley R. R. history, states that according to an interview with one of Hull's descendants the only alteration made to the _Pioneer_ during the 1871 "remodeling" was the addition of a handbrake. The road's annual report of 1853 describes the _Pioneer_ as a six-wheel tank engine. The report of 1854 mentions that the _Pioneer_ used link motion. These statements are enough to give substance to the idea that the basic arrangement has survived unaltered and that it has not been extensively rebuilt, as was the _Jenny Lind_ in 1878.
By the 1870's, the _Pioneer_ was too light for the heavier cars then in use and by 1880 it had reached the end of its usefulness for regular service. After nearly thirty years on the road it had run 255,675 miles. Two new passenger locomotives were purchased in 1880 to handle the heavier trains. In 1881 the _Pioneer_ was dropped from the roster, but was used until about 1890 for work trains. After this time it was stored in a shed at Falling Spring, Pennsylvania, near the Chambersburg yards of the C.V.R.R.
Mechanical Description of the _Pioneer_
After the early 1840's the single-axle locomotive, having one pair of driving wheels, was largely superseded by the 8-wheel engine. The desire to operate longer trains and the need for engines of greater traction to overcome the steep grades of American roads called for coupled driving wheels and machines of greater weight than the 4--2--0. After the introduction of the 4--4--0, the single-axle engine received little attention in this country except for light service or such special tasks as inspection or dummy engines.
There was, however, a renewed interest in "singles" in the early 1850's because of W. B. Adams' experiments with light passenger locomotives in England. In 1850 Adams built a light single-axle tank locomotive for the Eastern Counties Railway which proved very economical for light passenger traffic. It was such a success that considerable interest in light locomotives was generated in this country as well as in England. Nearly 100 single-axle locomotives were built in the United States between about 1845-1870. These engines were built by nearly every well-known maker, from Hinkley in Boston to the Vulcan Foundry in San Francisco. Danforth Cooke & Co. of Paterson built a standard pattern 4--2--4 used by many roads. One of these, the _C. P. Huntington_, survives to the present time.
The following paragraphs describe the mechanical details of the _Pioneer_ as it appears on exhibition in the Smithsonian Institution's new Museum of History and Technology.
BOILER
The boiler is the most important and costly part of a steam locomotive, representing one-fourth to one-third of the total cost. A poorly built or designed boiler will produce a poor locomotive no matter how well made the remainder of mechanism. The boiler of the _Pioneer_ is of the wagon-top, crownbar, fire-tube style and is made of a 5/16-inch thick, wrought-iron plate. The barrel is very small, in keeping with the size of the engine, being only 27 inches in diameter. While some readers may believe this to be an extremely early example of a wagon-top boiler, we should remember that most New England builders produced few locomotives with the Bury (dome) boiler and that the chief advocates of this later style were the Philadelphia builders. By the early 1850's the Bury boiler passed out of favor entirely and the wagon top became the standard type of boiler with all builders in this country.
Sixty-three iron tubes, 1-7/8 inches by 85 inches long are used. The original tubes may have been copper or brass since these were easier to keep tight than the less malleable iron tubes. The present tube sheet is of iron but was originally copper. Its thickness cannot be conveniently measured, but it is greater than that of the boiler shell, probably about 1/2 to 5/8 inch. While copper tubes and tube sheets were not much used in this country after about 1870, copper was employed as recently as 1950 by Robert Stephenson & Hawthorns, Ltd., on some small industrial locomotives.
The boiler shell is lagged with wooden tongue-and-groove strips about 2-1/2 inches wide (felt also was used for insulation during this period). The wooden lagging is covered with Russia sheet iron which is held in place and the joints covered by polished brass bands. Russia sheet iron is a planish iron having a lustrous, metallic gray finish.
The steam dome (fig. 18) is located directly over the firebox, inside the cab. It is lagged and jacketed in an identical manner to the boiler. The shell of the dome is of 5/16-inch wrought iron, the top cap is a cast-iron plate which also serves as a manhole cover offering access to the boiler's interior for inspection and repair.
A round plate, 20 inches in diameter, riveted on the forward end of the boiler, just behind the bell stand, was found when the old jacket was removed in May 1963. The size and shape of the hole, which the plate covers, indicate that a steam dome or manhole was located at this point. It is possible that this was the original location of the steam dome since many builders in the early 1850's preferred to mount the dome forward of the firebox. This was done in the belief that there was less danger of priming because the water was less agitated forward of the firebox.
The firebox is as narrow as the boiler shell and fits easily between the frame. It is a deep and narrow box, measuring 27 inches by 28 inches by about 40 inches deep, and is well suited to burning wood. A deep firebox was necessary because a wide, shallow box suitable for coal burning, allowed the fuel to burn so quickly it was difficult to fire the engine effectively. With the deep, narrow firebox, wood was filled up to the level of the fire door. In this way, the fire did not burn so furiously and did not keep ahead of the fireman; at the same time, since it burned so freely, a good fire was always on hand. The _Pioneer_ burned oak and hickory.[14] For the firebox 5/16-inch thick sheet was used, for heavier sheet would have blistered and flaked off because of the intense heat of the fire and the fibrous quality of wrought-iron sheet of the period. Sheet iron was fabricated from many small strips of iron rolled together while hot. These strips were ideally welded into a homogeneous sheet, but in practice it was found the thicker the sheet the less sure the weld.
The fire grates are cast iron and set just a few inches above the bottom of the water space so that the water below the grates remains less turbulent and mud or other impurities in the water settle here. Four bronze mud plugs and a blowoff cock are fitted to the base of the firebox so that the sediment thus collected can be removed (figs. 17, 18).
The front of the boiler is attached to the frame by the smokebox, which is a cylinder, bolted on a light, cast-iron saddle (not part of the cylinder castings nor attached to them, but bolted directly to the top rail of the frame; it may be a hastily made repair put on at the shops of the C.V.R.R.). The rear of the boiler is attached to the frame by two large cast-iron brackets, one on each side of the firebox (fig. 18). These are bolted to the top rail of the frame but the holes in the brackets are undoubtedly slotted, so that they may slide since the boiler will expand about 1/4 inch when heated. In addition to the crown bars, which strengthen the crown sheet, the boiler is further strengthened by stay bolts and braces located in the wagon top over the firebox, where the boiler had been weakened by the large hole necessary for the steam dome. This boiler is a remarkably light, strong, and compact structure.
BOILER FITTINGS
Few boiler fittings are found on the _Pioneer_ and it appears that little was done to update the engine with more modern devices during its many years of service. With the exception of the steam gauge, it has no more boiler fitting than when it left the builder's shop in 1851.
The throttle valve is a simple slide valve and must have been primitive for the time, for the balance-poppet throttle valve was in use in this country previous to 1851. It is located directly below the steam dome even though it was common practice to place the throttle valve at the front of the boiler in the smokebox. Considering the cramped condition inside the smokebox, there would seem to be little space for the addition of the throttle valve; hence its present location. The dry pipe projects up into the steam dome to gather the hottest, driest steam for the cylinders. The inverted, funnel-like cap on the top of the dry pipe is to prevent priming, as drops of water may travel up the sides of the pipe and then to the cylinders, with the possibility of great damage. After the steam enters the throttle valve it passes through the front end of the valve, through the top of the boiler via the dry pipe (fig. 18), through the front tube sheet, and then to the cylinders via the petticoat pipes. The throttle lever is a simple arrangement readily understood from the drawings. It has no latch and the throttle lever is held in any desired setting by the wingnut and quadrant shown in figure 18. The water level in the boiler is indicated by the three brass cocks located on the backhead. No gauge glass is used; they were not employed in this country until the 1870's, although they were commonly used in England at the time the _Pioneer_ was built.
While two safety valves were commonly required, only one was used on the _Pioneer_. The safety valve is located on top of the steam dome. Pressure is exerted on the lever by a spring balance, fixed at the forward end by a knife-blade bearing. The pressure can be adjusted by the thumbscrew on the balance. The graduated scale on the balance gave a general but uncertain indication of the boiler pressure. The valve itself is a poppet held against the face of the valve seat by a second knife blade attached to the lever. The ornamental column forming the stand of the safety valve is cast iron and does much to decorate the interior of the cab. The pipe carrying the escaping steam projects through the cab roof. It is made of copper with a decorative brass band. This entire mechanism was replaced by a modern safety valve for use at the Chicago Railroad Fair (1949). Fortunately, the old valve was preserved and has since been replaced on the engine.
The steam gauge is a later addition, but could have been put on as early as the 1860's, since the most recent patent date that it bears is 1859. It is an Ashcroft gauge having a handsome 4--4--0 locomotive engraved on its silver face.
The steam jet (item 3, fig. 18) is one of the simplest yet most notable boiler fitting of the _Pioneer_, being nothing more than a valve tapped into the base of the steam dome with a line running under the boiler jacket to the smokestack. When the valve is opened a jet of steam goes up the stack, creating a draft useful for starting the fire or enlivening it as necessary. This device was the invention of Alba F. Smith in 1852, according to the eminent 19th-century technical writer and engineer Zerah Colburn.[15]
The two feedwater pumps (fig. 20) are located beneath the cab deck (1, fig. 17). They are cast-iron construction and are driven by an eccentric on the driving-wheel axle (fig. 27). The airchamber or dome (1, fig. 27) imparts a more steady flow of the water to the boiler by equalizing the surges of water from the reciprocating pump plunger. A steam line (3, fig. 18), which heats the pump and prevents freezing in cold weather, is regulated by a valve in the cab (figs. 18, 27). Note that the line on the right side of the cab has been disconnected and plugged.
The eccentric drive for the pumps is unusual, and the author knows of no other American locomotive so equipped. Eastwick and Harrison, it is true, favored an eccentric drive for feed pumps, but they mounted the eccentric on the crankpin of the rear driving wheel and thus produced in effect a half-stroke pump. This was not an unusual arrangement, though a small crank was usually employed in place of the eccentric. The full-stroke crosshead pump with which the _Jenny Lind_ (fig. 22) is equipped, was of course the most common style of feed pump used in this country in the 19th century.
Of all the mechanisms on a 19th-century locomotive, the feed pump was the most troublesome. If an engineer could think of nothing else to complain about, he could usually call attention to a defective pump and not be found a liar. Because of this, injectors were adopted after their introduction in 1860. It is surprising that the _Pioneer_, which was in regular service as late as 1880 and has been under steam many times since for numerous exhibitions, was never fitted with one of these devices. Because its stroke is short and the plunger is in less rapid motion, the present eccentric arrangement is more complex but less prone to disorder than the simpler but faster crosshead pump.
The check valves are placed slightly below the centerline of the boiler (fig. 18). These valves are an unfinished bronze casting and appear to be of a recent pattern, probably dating from the 1901 renovation. At the time the engine was built, it was usual to house these valves in an ornamental spun-brass casing. The smokestack is of the bonnet type commonly used on wood-burning locomotives in this country between about 1845 and 1870. The exhaust steam from the cylinders is directed up the straight stack (shown in phantom in fig. 27) by the blast pipe. This creates a partial vacuum in the smokebox that draws the fire, gases, ash, and smoke through the boiler tubes from the firebox. The force of the exhausting steam blows them out the stack. At the top of the straight stack is a deflecting cone which slows the velocity of the exhaust and changes its direction causing it to go down into the funnel-shaped outer casing of the stack. Here, the heavy embers and cinders are collected and prevented from directly discharging into the countryside as dangerous firebrands. Wire netting is stretched overtop of the deflecting cone to catch the lighter, more volatile embers which may defy the action of the cone. The term "bonnet stack" results from the fact that this netting is similar in shape to a lady's bonnet. The cinders thus accumulated in the stack's hopper could be emptied by opening a plug at the base of the stack.
While the deflecting cone was regarded highly as a spark arrester and used practically to the exclusion of any other arrangement, it had the basic defect of keeping the smoke low and close to the train. This was a great nuisance to passengers, as the low trailing smoke blew into the cars. If the exhaust had been allowed to blast straight out the stack high into the air, most of the sparks would have burned out before touching the ground.
FRAME
The frame of the _Pioneer_ defies an exact classification but it more closely resembles the riveted- or sandwich-type frame than any other (figs. 18, 27). While the simple bar frame enjoyed the greatest popularity in the last century, riveted frames were widely used in this country, particularly by the New England builders between about 1840 and 1860. The riveted frame was fabricated from two plates of iron, about 5/8-inch thick, cut to the shape of the top rail and the pedestal. A bar about 2 inches square was riveted between the two plates. A careful study of photographs of Hinkley and other New England-built engines of the period will reveal this style of construction. The frame of the _Pioneer_ differs from the usual riveted frame in that the top rail is 1-3/4 inches thick by 4-1/8 inches deep and runs the length of the locomotive. The pedestals are made of two 3/8-inch plates flush-riveted to each side of the top rail. The cast-iron shoes which serve as guides for the journal boxes also act as spacers between the pedestal plates.
The bottom rail of the frame is a 1-1/8-inch diameter rod which is forged square at the pedestals and forms the pedestal cap. The frame is further stiffened by two diagonal rods running from the top of each truck-wheel pedestal to the base of the driving-wheel pedestal, forming a truss. Six rods, riveted to the boiler shell and bolted to the frame's top rail, strengthen the frame laterally. Four of these rods can be seen easily as they run from the frame to the middle of the boiler; the other two are riveted to the underside of the boiler. The attachment of these rods to the boiler was an undesirable practice, for the boiler shell was thus subjected to the additional strain of the locomotive's vibrations as it passed over the road. In later years, as locomotives grew in size, this practice was avoided and frames were made sufficiently strong to hold the engine's machinery in line without using the boiler shell.
The front and rear frame beams are of flat iron plate bolted to the frame. The rear beam had been pushed in during an accident, and instead of its being replaced, another plate was riveted on and bent out in the opposite direction to form a pocket for the rear coupling pin. Note that there is no drawbar and that the coupler is merely bolted to the beams. Since the engine only pulled light trains, the arrangement was sufficiently strong.
RUNNING GEAR
The running gear is simply sprung with individual leaf springs for each axle; it is not connected by equalizing levers. To find an American locomotive not equipped with equalizers is surprising since they were almost a necessity to produce a reasonably smooth ride on the rough tracks of American railroads. Equalizers steadied the motion of the engine by distributing the shock received by any one wheel or axle to all the other wheels and axles so connected, thus minimizing the effects of an uneven roadbed. The author believes that the _Pioneer_ is a hard-riding engine.
The springs of the main drives are mounted in the usual fashion. The rear boiler bracket (fig. 18) is slotted so that the spring hanger may pass through for its connection with the frame. The spring of the leading wheels is set at right angles to the frame (fig. 27) and bears on a beam, fabricated of iron plate, which in turn bears on the journal boxes. The springs of the trailing wheels are set parallel with the frame and are mounted between the pedestal plates (fig. 18).
The center of the driving wheel is cast iron and has spokes of the old rib pattern, which is a T in cross section, and was used previous to the adoption of the hollow spoke wheel. In the mid-1830's Baldwin and others used this rib-pattern style of wheel, except that the rib faced inside. The present driving-wheel centers are unquestionably original. The sister engine _Jenny Lind_ (fig. 22) was equipped with identical driving wheels. The present tires are very thin and beyond their last turning. They are wrought iron and shrunk to fit the wheel centers. Flush rivets are used for further security. The left wheel, shown in figure 17, is cracked at the hub and is fitted with an iron ring to prevent its breaking.
The truck wheels, of the hollow spoke pattern, are cast iron with chilled treads. They were made by Asa Whitney, one of the leading car-wheel manufacturers in this country, whose extensive plant was located in Philadelphia. Made under Whitney's patent of 1866, these wheels may well have been added to the _Pioneer_ during the 1871 rebuilding. Railroad wheels were not cast from ordinary cast iron, which was too weak and brittle to stand the severe service for which they were intended, but from a high-quality cast iron similar to that used for cannons. Its tensile strength, which ranged from 31,000 to 36,000 psi, was remarkably high and very nearly approached that of the best wrought-iron plate.
The cylinders are cast iron with an 8-1/2-inch bore about half the size of the cylinders of a standard 8-wheel engine. The cylinders are bolted to the frame but not to the saddle, and are set at a 9 deg. angle to clear the leading wheels and at the same time to line up with the center of the driving-wheel axle. The wood lagging is covered with a decorative brass jacket. Ornamental brass jacketing was extensively used on mid-19th-century American locomotives to cover not only the cylinders but steam and sand boxes, check valves, and valve boxes. The greater expense for brass (Russia iron or painted sheet iron were a cheaper substitute) was justified by the argument that brass lasted the life of the engine, and could be reclaimed for scrap at a price approaching the original cost; and also that when brightly polished it reflected the heat, preventing loss by radiation, and its bright surface could be seen a great distance, thus helping to prevent accidents at grade crossings. The reader should be careful not to misconstrue the above arguments simply as rationalization on the part of master mechanics more intent on highly decorative machines than on the practical considerations involved.
The valve box, a separate casting, is fastened to the cylinder casting by six bolts. The side cover plates when removed show only a small opening suitable for inspection and adjustment of the valve. The valve box must be removed to permit repair or removal of the valve. A better understanding of this mechanism and the layout of the parts can be gained from a study of figures 23-26, 28 (8, 8A, and 8B).
Both crossheads were originally of cast iron but one of these has been replaced and is of steel. They run into steel guides, bolted at the forward end to the rear cylinder head and supported in the rear by a yoke. The yoke is one of the more finished and better made pieces on the entire engine (fig. 27). The main rod is of the old pattern, round in cross section, and only 1-1/2 inches in diameter at the largest point.
VALVE GEAR
The valve gear is of the Stephenson shifting-link pattern (see fig. 27), a simple and dependable motion used extensively in this country between about 1850 and 1900. The author believes that this is the original valve gear of the _Pioneer_, since the first mention (1854) in the _Annual Report_ of the Cumberland Valley Railroad of the style of valve gear used by each engine, states that the _Pioneer_ was equipped with a shifting-link motion. Assuming this to be the original valve gear of the _Pioneer_, it must be regarded as an early application, because the Stephenson motion was just being introduced into American locomotive practice in the early 1850's. Four eccentrics drive the motion; two are for forward motion and two for reverse. The link is split and made of two curved pieces. The rocker is fabricated of several forged pieces keyed and bolted together. On better made engines the rocker would be a one-piece forging. The lower arm of each rocker is curiously shaped, made with a slot so that the link block may be adjusted. Generally, the only adjustment possible was effected by varying the length of the valve stem by the adjusting nuts provided. A simple weight and lever attached to the reversing shaft serve as a counterbalance for the links and thus assist the engineer in shifting the valve motion. There are eight positions on the quadrant of the reversing lever.
MISCELLANEOUS NOTES
The cab is solid walnut with a natural finish. It is very possible that the second cab was added to the locomotive after the 1862 fire. A brass gong used by the conductor to signal the engineer is fastened to the underside of the cab roof. This style of gong was in use in the 1850's and may well be original equipment.
The water tank is in two sections, one part extending below the deck, between the frame. The tank holds 600 gallons of water. The tender holds one cord of wood.
The small pedestal-mounted sandbox was used on several Cumberland Valley engines including the _Pioneer_. This box was removed from the engine sometime between 1901 and 1904. It was on the engine at the time of the Carlisle sesquicentennial but disappeared by the time of the St. Louis exposition. Two small sandboxes, mounted on the driving-wheel splash guards, replaced the original box. The large headlamp (fig. 3) apparently disappeared at the same time and was replaced by a crudely made lamp formerly mounted on the cab roof as a backup light. Headlamps of commercial manufacture were carefully finished and made with parabolic reflectors, elaborate burners, and handsomely fitted cases. Such a lamp could throw a beam of light for 1000 feet. The present lamp has a flat cone-shaped piece of tin for a reflector.
The brushes attached to the pilot were used in the winter to brush snow and loose ice off the rail and thus improve traction. In good weather the brushes were set up to clear the tracks.
After the _Pioneer_ had come to the National Museum, it was decided that some refinishing was required to return it as nearly as possible to the state of the original engine. Replacing the sandbox was an obvious change.[20] The brass cylinder jackets were also replaced. The cab was stripped and carefully refinished as natural wood. The old safety valve was replaced, as already mentioned. Rejacketing the boiler with simulated Russia iron produced a most pleasing effect, adding not only to the authenticity of the display but making the engine appear lighter and relieving the somber blackness which was not characteristic of a locomotive of the 1850's. Several minor replacements are yet to be done; chiefly among these are the cylinder-cock linkage and a proper headlamp.
The question arises, has the engine survived as a true and accurate representation of the original machine built in 1851? In answer, it can be said that although the _Pioneer_ was damaged en route to the Cumberland Valley Railroad, modified on receipt, burned in 1862, and operated for altogether nearly 40 years, surprisingly few new appliances have been added, nor has the general arrangement been changed. Undoubtedly, the main reason the engine is so little changed is that its small size and odd framing did not invite any large investment for extensive alteration for other uses. But there can be no positive answer as to its present variance from the original appearance as represented in the oldest known illustration of it--the Hull drawing of 1871 (fig. 8). There are few, if any, surviving 19th-century locomotives that have not suffered numerous rebuildings and are not greatly altered from the original. The _John Bull_, also in the U.S. National Museum collection, is a good example of a machine many times rebuilt in its 30 years of service.[21] Unless other information is uncovered to the contrary, it can be stated that the _Pioneer_ is a true representation of a light passenger locomotive of 1851.
_Alba F. Smith_
Alba F. Smith, the man responsible for the purchase of the _Pioneer_, was born in Lebanon, Connecticut, June 28, 1817.[9] Smith showed promise as a mechanic at an early age and by the time he was 22 had established leadpipe works in Norwich. His attention was drawn particularly to locomotives since the tracks of the Norwich and Worcester Railroad passed his shop. His attempts to develop a spark arrester for locomotives brought Smith to the favorable attention of Captain Daniel Tyler (1799-1882), president of the Norwich and Worcester Railroad. When Tyler was hired by the Cumberland Valley Railroad in 1850 to supervise the line's rebuilding, he persuaded the managers of that road to hire Smith as superintendent of machinery.[10] Smith was appointed as superintendent of the machine shop of the Cumberland Valley Railroad on July 22, 1850.[11] On January 1, 1851, he became superintendent of the road.
In March of 1856 Smith resigned his position with the Cumberland Valley Railroad and became superintendent of the Hudson River Railroad, where he remained for only a year. During that time he designed the coal-burning locomotive _Irvington_, rebuilt the Waterman condensing dummy locomotive for use in hauling trains through city streets, and developed a superheater.[12]
After retiring from the Hudson River Railroad he returned to Norwich and became active in enterprises in that area, including the presidency of the Norwich and Worcester Railroad. While the last years of Smith's life were devoted to administrative work, he found time for mechanical invention as well. In 1862 he patented a safety truck for locomotives, and became president of a concern which controlled the most important patents for such devices.[13] Alba F. Smith died on July 21, 1879, in Norwich, Connecticut.
MANUFACTURER OF
LOCOMOTIVES,
STATIONARY STEAM ENGINES AND STEAM BOILERS,
OF THE VARIOUS SIZES REQUIRED,
_Parts connected with Railroads, including Frogs, Switches, Chairs and Hand Cars._
MACHINISTS' TOOLS, of all descriptions, including _TURNING LATHES_, of sizes varying from 6 feet to 50 feet in length, and weighing from 500 pounds to 40 tons each; the latter capable of turning a wheel or pulley, _thirty feet in diameter_.
PLANING MACHINES,
Varying from 2 feet to 60 feet in length, and weighing from 200 lbs. to 70 tons each, and will plane up to 55 feet long and 7 feet square.
Boring Mills, Vertical and Horizontal Drills, Slotting Machines, Punching Presses, Gear and Screw Cutting Machines, &c. &c. Also,
Mill Gearing and Shafting.
JOBBING AND REPAIRS, and any kind of work usually done in Machine Shops, executed at short notice.
Figure 13.--ADVERTISEMENT OF SETH WILMARTH appearing in Boston city directory for 1848-1849.]
_Seth Wilmarth_
Little is known of the builder of the _Pioneer_, Seth Wilmarth, and nothing in the way of a satisfactory history of his business is available. For the reader's general interest the following information is noted.[16]
Seth Wilmarth was born in Brattleboro, Vermont, on September 8, 1810. He is thought to have learned the machinist trade in Pawtucket, Rhode Island, before coming to Boston and working for the Boston Locomotive Works, Hinkley and Drury proprietors. In about 1836 he opened a machine shop and, encouraged by an expanding business, in 1841 he built a new shop in South Boston which became known as the Union Works.[17] Wilmarth was in the general machine business but his reputation was made in the manufacture of machine tools, notably lathes. He is believed to have built his first locomotive in 1842, but locomotive building never became his main line of work. Wilmarth patterned his engines after those of Hinkley and undoubtedly, in common with the other New England builders of this period, favored the steady-riding, inside-connection engines. The "Shanghais," so-called because of their great height, built for the Boston and Worcester Railroad by Wilmarth in 1849, were among the best known inside-connection engines operated in this country (fig. 14). While the greater part of Wilmarth's engines was built for New England roads, many were constructed for lines outside that area, including the Pennsylvania Railroad, Ohio and Pennsylvania Railroad, and the Erie.
A comparison of the surviving illustrations of Hinkley and Wilmarth engines of the 1850's reveals a remarkable similarity in their details (figs. 14 and 15). Notice particularly the straight boiler, riveted frame, closely set truck wheels, feedwater pump driven by a pin on the crank of the driving wheel, and details of the dome cover. All of the features are duplicated exactly by both builders. This is not surprising considering the proximity of the plants and the fact that Wilmarth had been previously employed by Hinkley.
In 1854 Wilmarth was engaged by the New York and Erie Railroad to build fifty 6-foot gauge engines.[18] After work had been started on these engines, and a large store of material had been purchased for their construction, Wilmarth was informed that the railroad could not pay cash but that he would have to take notes in payment.[19] There was at this time a mild economic panic and notes could be sold only at a heavy discount. This crisis closed the Union Works. The next year, 1855, Seth Wilmarth was appointed master mechanic of the Charlestown Navy Yard, Boston, where he worked for twenty years. He died in Malden, Massachusetts, on November 5, 1886.
* * * * *
FOOTNOTES
[1] _Minutes of the Board of Managers of the Cumberland Valley Railroad._ This book may be found in the office of the Secretary, Pennsylvania Railroad, Philadelphia, Pa., June 25, 1851. Hereafter cited as "Minutes C.V.R.R."
[2] Ibid.
[3] Minutes C.V.R.R.
[4] _Franklin Repository_ (Chambersburg, Pa.), August 26, 1909.
[5] _Railroad Advocate_ (December 29, 1855), vol. 2, p. 3.
[6] C. E. FISHER, "Locomotives of the New Haven Railroad," _Railway and Locomotive Historical Society Bulletin_ (April 1938), no. 46, p. 48.
[7] Minutes C.V.R.R.
[8] _Evening Sentinel_ (Carlisle, Pa.), October 23, 1901.
[9] _Norwich Bulletin_ (Norwich, Conn.), July 24, 1879. All data regarding A. F. Smith is from this source unless otherwise noted.
[10] _Railway Age_ (September 13, 1889), vol. 14, no. 37. Page 600 notes that Tyler worked on C.V.R.R. 1851-1852; Smith's obituary (footnote 9) mentions 1849 as the year; and minutes of C.V.R.R. mention Tyler as early as 1850.
[11] Minutes C.V.R.R.
[12] A. F. HOLLEY, _American and European Railway Practice_ (New York: 1861). An illustration of Smith's superheater is shown on plate 58, figure 13.
[13] JOHN H. WHITE, "Introduction of the Locomotive Safety Truck," (Paper 24, 1961, in _Contributions from the Museum of History and Technology: Papers 19-30_, U.S. National Museum Bulletin 228; Washington: Smithsonian Institution, 1963), p. 117.
[14] _Annual Report_, C.V.R.R., 1853.
[15] ZERAH COLBURN, _Recent Practice in Locomotive Engines_ (1860), p. 71.
[16] _Railroad Gazette_ (September 27, 1907), vol. 43, no. 13, pp. 357-360. These notes on Wilmarth locomotives by C. H. Caruthers were printed with several errors concerning the locomotives of the Cumberland Valley Railroad and prompted the preparation of these present remarks on the history of Wilmarth's activities. Note that on page 359 it is reported that only one compensating-lever engine was built for the C.V.R.R. in 1854, and not two such engines in 1852. The _Pioneer_ is incorrectly identified as a "Shanghai," and as being one of three such engines built in 1871 by Wilmarth.
[17] The author is indebted to Thomas Norrell for these and many of the other facts relating to Wilmarth's Union Works.
[18] _Railroad Gazette_ (October 1907), vol. 43, p. 382.
[19] _Boston Daily Evening Telegraph_ (Boston, Mass.), August 11, 1854. The article stated that one engine a week was built and that 10 engines were already completed for the Erie. Construction had started on 30 others.
[20] The restoration work has been ably handled by John Stine of the Museum staff. Restoration started in October 1961.
[21] S. H. OLIVER, _The First Quarter Century of the Steam Locomotive in America_ (U.S. National Museum Bulletin 210; Washington: Smithsonian Institution, 1956), pp. 38-46.
* * * * *
PAPER 42: Typographical Corrections
Page 259: "as late as 1880 and has been under steam" (was stream).
Page 267: "made with parabolic reflectors" (was parobolic).
* * * * *
CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY:
PAPER 43
HISTORY OF THE DIVISION OF MEDICAL SCIENCES
by
SAMI HAMARNEH
SECTION OF MATERIA MEDICA (1881-1898) 272
DIVISION OF MEDICINE (1898-1939) 276
DIVISION OF MEDICINE AND PUBLIC HEALTH (1939-1957) 281
DIVISION OF MEDICAL SCIENCES (1957 TO PRESENT) 290
A NEW DIMENSION FOR THE HEALING ARTS 292
BIBLIOGRAPHY 297
FOOTNOTES
_Sami Hamarneh_
HISTORY of the DIVISION of MEDICAL SCIENCES _In The Museum of History and Technology_
_This paper traces, for the first time, the history of the Division of Medical Sciences in the Museum of History and Technology from its small beginnings as a section of materia medica in 1881 to its present broad scope. The original collection of a few hundred specimens of crude drugs which had been exhibited at the centennial exhibition of 1876 at Philadelphia, has now developed into the largest collection in the Western Hemisphere of historical objects related to the healing arts._
THE AUTHOR: _Sami Hamarneh is the curator of the Division of Medical Sciences in the Smithsonian Institution's Museum of History and Technology._
By the early 1870's, leading figures from both the health professions and the general public had begun to realize the necessity for having the medical sciences represented in the Smithsonian Institution. The impetus behind this new feeling resulted from the action of a distinguished American physician, philanthropist, and author, Joseph Meredith Toner (1825-1896), and came almost a decade before the integration of a new section concerned with research and the historical and educational aspects of the healing arts in the Smithsonian Institution.
In 1872, Dr. Toner established the "Toner Lectures" to encourage efforts towards discovering new truths "for the advancement of medical science ... for the benefit of mankind." To finance these lectures, he provided a fund worth approximately $3,000 to be administered by a board of trustees consisting of the Secretary of the Smithsonian Institution, the Surgeon General of the U.S. Navy, the Surgeon General of the U.S. Army (only in some years), and the president of the Medical Society of the District of Columbia. The interest from this fund was to compensate physicians and scholars who were to deliver "at least two annual memoirs or essays" based on original research on some branch of the medical sciences and containing information which had been verified "by experiments or observations."[1]
The Secretary of the Smithsonian Institution agreed to have these lectures published by the Institution in its Miscellaneous Collections. The first lecture given by the Assistant Surgeon of the U.S. Army, "On the Structure of Cancerous Tumors and the Mode in which Adjacent parts are Invaded," deserves credit even by current standards of scientific research.[2] Only 10 lectures were given between 1873 and 1890 (see bibliography), despite the recommendation for at least two every year.[3]
A more direct factor, which not only contributed to the establishment of a section on the healing arts, but also had a greater effect upon the Smithsonian Institution than any other event since its founding, was the 1876 centennial exhibition in Philadelphia.
This magnificent international fair commemorated the hundredth anniversary of the adoption of the Declaration of Independence. The finest exhibits of 30 foreign countries and various States of the Union participating in the fair were finally donated to the Smithsonian Institution as the official depository of historical and archeological objects for this country. As a result, the Institution's collections increased to an extent far beyond the capacity of the first Smithsonian building. This led to the erection of the National Museum, known for the last two decades and until date of publication as the Arts and Industries building, which was completed on March 4, 1881, and was used that evening for the inaugural reception of incoming President James A. Garfield.
Section of Materia Medica (1881-1898)
Throughout the 19th century, the study of _materia medica_ (dealing with the nature and properties of drugs of various kinds and origins, their collection and mode of administration for the treatment of diseases, and the medicinal utilization of animal products) held an increasingly important place among the medical sciences. In the United States, as in other civilized countries, this topic was greatly emphasized in the curriculum of almost every school teaching the health professions. Today, the subject matter contained in this branch of science is taught under the heading of several specialized fields, such as pharmacology, pharmacognosy, and drug analysis of various types. However, when the decision was made in 1881 to promote greater knowledge and interest in the healing arts by creating a section devoted to such pursuits in the U.S. National Museum, the title of Section of Materia Medica was adopted. Added to this, was the fact that the bulk of the first collections received in the Section was a great variety of crude drugs, which constituted much of the material then taught in the academic courses of _materia medica_.
The new Section was included in the Department of Arts and Industries, then under the curatorship of Assistant Director G. Brown Goode. From its beginning and for two decades, however, the Section of Materia Medica was sponsored and supervised by the U.S. Navy in cooperation with the Smithsonian Institution. For this reason, the Navy decided not to establish a similar bureau for a health museum as did the Army in starting the Medical Museum (of the Armed Forces Institute of Pathology) in 1862 through the efforts of Dr. William Alexander Hammond. The Smithsonian did, however, provide a clerk to relieve the curator of much of the routine work. The Section's early vigorous activities were the result of the ingenuity of the first honorary curator, Dr. James Milton Flint (1838-1919), an Assistant Surgeon of the U.S. Navy. From the establishment of the Section, in 1881, to 1912, Dr. Flint was curator during separate periods for a total of nearly 25 years. For three of his tenures (1881-1884; 1887-1891; 1895-1900), he was detailed to the Smithsonian Institution by the Surgeon General of the U.S. Navy. During the interim periods, other naval doctors were detailed as curators. Finally, in 1900, Dr. Flint retired from the Navy with the rank of Rear Admiral and volunteered to continue his services to the National Museum. The proposal was gladly accepted and he continued as a curator until his retirement from the Smithsonian Institution in 1912.
The Section commenced with a wealth of material. After the close of the 1876 centennial exhibition, its _materia medica_ collection had been stored with the other collections in a warehouse, awaiting an appropriation by Congress for transfer and installation. This collection was gradually brought into the new National Museum after that building's completion in 1881. Many other _materia medica_ specimens were transferred from the Department of Agriculture. In addition to these large collections of crude drugs, generous contributions came from several prominent pharmaceutical firms such as Parke, Davis & Company of Detroit, Michigan; Wallace Brothers of Statesville, North Carolina; and Schieffelin and Company of New York City. These manufacturing houses are mentioned here because they and their agents abroad were the first to take interest and donate to the Section, complete assortments of contemporary remedial agents then in common use throughout the United States and Europe, besides many hundreds of "rare and curious drugs." Thus, in spite of difficulties encountered from bringing several collections into the building at one time, the _materia medica_ exhibition got off to a good start.
It was Dr. Flint, the first curator, who stated in 1883 that remedial agents used by a nation or a community are as indicative of the degree of their cultural development and standard of living as is the nature of their food, the character of their dwellings, and their social and religious traditions. Therefore, he felt that collections of drugs and medical, surgical and pharmaceutical instruments and appliances should not be thought of or designed as instructive to the specialist only, but should also possess a general interest for the public. Because of these objectives, Dr. Flint added, this section was conceived as a departmental division for the collecting and exhibiting of objects related to medicine, surgery, pharmacology, hygiene, and all material related to the health field at large.[4]
During his first term of curatorship (1881-1884), Dr. Flint devoted much of his time to sorting, examining, identifying, and classifying the _materia medica_ specimens.[5] In 1881, he issued a memorandum of instructions to be followed by collectors of drugs and urged them to give detailed and accurate information regarding acquired specimens so that they might be "more than mere museum curiosities." In addition, in 1883, he prepared a brief manual of classification of the _materia medica_ collection in the Museum as well as a useful, detailed catalog of informational labels of the individual objects on exhibition. The unpublished catalog is still the property of the Smithsonian Institution Archives, Division of Medical Sciences' Library.
It was Dr. Flint's ambition to obtain a comprehensive, worldwide collection of all substances used as remedies. Then, in order to identify drugs from foreign countries, he tried to collect illustrated works on medical botany and printed pharmacopoeias of all nations having them. He rightly defined an official pharmacopoeia as "a book containing directions for the identification and preparation of medicines prepared and issued with the sanction of a government or organized and authorized medical and pharmaceutical societies. Its purpose is to establish uniformity in the nomenclature of remedies and in the character and potency of the pharmaceutical preparations. It is enacted by legislation, and thus becomes binding on all who prepare drugs or sell them for medication." By soliciting the help of various American consuls and Navy officers abroad, about 16 such official pharmacopoeias were collected, making an almost complete international representation of all available, official, drug standards. With these sources of information, Dr. Flint compiled and arranged an international list of _materia medica_ specimens, indicating the authorized preparations of each. By so doing, the first curator of this Section took the initiative at least in proposing and, to some extent acting, on the preparation of an international pharmacopoeia of drugs used in existing authorized formularies giving "official synonyms, and tables showing the constituents and comparative strength of all preparations."[6] This undertaking is of special importance in the history of American pharmacy, since it was probably the first attempt of its kind in the United States.[7] In addition, colored plates and photographs of medicinal plants were collected, forming the nucleus of the Division's current collection of pictorial and photographic material related to the history of the health field.
Dr. Flint also put on exhibition 630 Chinese _materia medica_ specimens from the 1876 Philadelphia centennial. These had been collected originally by the Chinese Imperial Customs Commission for the centennial and were subsequently given to this country.
In 1881, the numbered objects in the Section's register amounted to 1,574 entries. In the following year, 1,590 more specimens were added, most of them drugs in their crude state. By the end of 1883, the total collection had reached 4,037, out of which 3,240 individual drugs in good condition were classified and put on display. Of these, about 500 specimens with beautiful illustrations of parts of their original plants had been mounted for exhibition. The drug exhibitions also included materials transferred from the Department of Agriculture in 1881, which originally had been brought from Central America and South America for the 1876 centennial exhibition, a variety of opium specimens from Turkey, and a number of rare drugs listed in the official formulary which were acquired from the Museum of Karachi in what was then India.
Dr. Flint commented in the _Smithsonian Annual Report_ for 1883 that the collection of cinchona barks was especially complete. It was comprised of specimens of nearly all the natural cinchona barks of South America and every known variety of the cultivated product from the British government plantations in India. In addition, there were specimens from Java, Ceylon, Mexico, and Jamaica. The Indian and Jamaican barks were accompanied by herbarium specimens of the leaf and flower (and, in some cases, the fruit) of each variety of tree from which the bark was obtained.[8]
In an attempt to protect specimens liable to attack by insects, a small piece of blotting paper moistened with chloroform was inserted underneath the stopper in each bottle. Later on, bichloride of mercury was found to be a better insecticide.
These early collections of the Section were brought into admirable condition and received compliments for their organization and completeness. In the _Smithsonian Annual Report_ for 1883, the collections were praised as "superior to any other in the United States and scarcely excelled by any in Europe."
In spite of the apparent emphasis on the displaying of drugs, the first curator of the Section had envisioned that the exhibits eventually would embrace the entire field of the healing arts. In the _Smithsonian Annual Report_ for 1883, Dr. Flint noted that "in the establishment of a museum designed to illustrate man and his environment, it is proper that the materials and methods used for the prevention and cure of disease should have a place." However, his plans were temporarily interrupted when his first term as honorary curator ended in 1884.
On June 4, 1884, Dr. Henry Gustav Beyer was detailed by the Department of the Navy to become the second honorary curator of the Section of Materia Medica. As a young man, Dr. Beyer (1850-1918) had come from Saxony, Germany, to the United States and, in due course, became a naturalized citizen. He was graduated from the Bellevue Hospital Medical College of New York City in 1876.
Because of his interest in physiological experimental research, Dr. Beyer enrolled at the Johns Hopkins University, where he was awarded a Ph. D. degree in 1887. Unlike his predecessor, Dr. Beyer was primarily interested in carrying on research on the physiological action of certain drugs and in pharmacology. This was evident from the original scientific papers mentioned in the _Smithsonian Annual Reports_ and published by him during the period of his curatorship from 1884 to 1887.
Despite the pressure of his postgraduate studies at Johns Hopkins University, Dr. Beyer helped in arranging and classifying the _materia medica_ collection without trying to extend materially the scope of the Section.
After the term of Dr. Beyer expired in 1887, Dr. Flint returned to take charge of the Section. Surprisingly, at this time, it seems that he showed less enthusiasm and devotion to the work of the Museum which he had previously served so well. It could have been a disappointment resulting from a lack of evidence of any real progress in the Section since he had left it three years before. Whatever the reasons may have been, the _Smithsonian Annual Reports_ show that only a few hundred specimens were added to the _materia medica_ collections between 1887 and 1890, bringing the total to 5,915 preserved in good condition. Further curtailment of the Section's activities began in November 1891 when Dr. Flint was again transferred to other duties for the U.S. Navy. From November 1891 to May 24, 1895, curatorship of the Section was charged to five physicians of the U.S. Navy: Drs. John C. Boyd (from November 1891 to April 6, 1892); William S. Dixon (April 1892 to January 5, 1893); C. H. White (January 1893 to July 15, 1893); C. U. Gravatt (July 1893 to January 22, 1894); R. A. Marmion (January 22, 1894 to June 15, 1894); and to Medical Inspector Daniel McMurtrie (June 1894 to May 24, 1895). During this interim of nearly three and a half years, there were neither literary contributions nor additions made to the collections of the Section that were of any significance. The reason is obvious, for all of these curators averaged less than seven months of service which is not enough time, even for a well-trained individual, to accomplish very much in a museum. Therefore, it is easy to imagine that when the Secretary of the Navy detailed Dr. Flint for a third time to take charge of the Section, he was rather discouraged. Nevertheless, at the Cotton States and International Exposition in Atlanta, Georgia, from September 18 to December 31, 1895, the _materia medica_ was represented by two displays: one on mineral waters and amounts of solid constituents in pure state; and another showing the quantities of minerals after analysis of the composition of the human body.
A similar project was undertaken in 1897 at the Tennessee Centennial Exposition (May 1 to October 31) in Nashville, where there were two displays of _materia medica_. One showed several kinds of the cinchona barks and the medicinal preparations made from them, and another containing the commercial varieties of the alkaloids of opium.
At this time, Dr. Flint's attention turned to a new phase of medical exhibition. He felt the need for a program of exhibits on the practice and the historical development of the healing arts. A change of the Section's name was deemed necessary and, thus, in 1898 the more comprehensive title of Division of Medicine was adopted.
Division of Medicine (1898-1939)
The statement by L. Emmett Holt of the Rockefeller Institute for Medical Research, that before 1906, the Smithsonian Institution was never a beneficiary to medicine in any form,[9] is not entirely applicable. The previous discussion has clearly shown that the U.S. National Museum's cooperation with the Navy contributed materially towards encouraging and promoting medical knowledge. Furthermore, Dr. Flint tried to bring many of his plans for this medical division of the Museum to a practical fulfillment. He devised a program for presenting medical history in a way which would be of interest both to the public and to the profession. In order to best illustrate the history of the healing art, he divided his subject matter into five provisional classifications according to the _Report upon the Condition and Progress of the U.S. National Museum_ during 1898:
1. Magical medicine including exorcism, amulets, talismans, fetishes and incantation;
2. Psychical medicine including faith cures, and hypnotism;
3. Physical and external medicine including baths, exercise, electricity, massage, surgery, cautery, and blood-letting;
4. Internal medicine including medications and treatment used by the ancient Egyptians, Greeks, Hindus, Arabians, and Chinese; and
5. Preventive medicine including beverages, food, soil, clothing and habitation.
It is certainly to Dr. Flint's credit that from its early conception, first as Section of Materia Medica and thereafter as Division of Medicine, he planned for an all-embracing exhibition and reference collection of the medical sciences. Until the end of the 19th century and the early years of the 20th century, crude drugs as well as primitive and magic medicine held a more prominent place than medical instruments in the exhibits and collections. In 1905, Flint issued his last, known, literary contribution, "Directions for Collecting Information and Objects Illustrating the History of Medicine," in Part S of _Bulletin of the U.S. National Museum_, no. 39. The emphasis he put upon this shows Dr. Flint's interest in collecting medical and pharmaceutical objects and equipment of historical value. Consequently, he arranged new exhibits including one on American Indian medicine. A medical historian, Fielding H. Garrison, inspected these about 1910 and, in his "An Introduction to the History of Medicine," wrote of their novelty and appeal. "In the interesting exhibit of folk medicine in the National Museum at Washington," he commented, "a buckeye or horse chestnut (_Aesculus flavus_), an Irish potato, a rabbit's foot, a leather strap previously worn by a horse, and a carbon from an arc light are shown as sovereign charms against rheumatism. Other amulets in the Washington exhibit," he added, "are the patella of a sheep and a ring made out of a coffin nail (dug out of a graveyard) for cramps and epilepsy, a peony root to be carried in the pocket against insanity, and rare and precious stones for all and sundry diseases." It had been Dr. Flint's intention, besides presenting an educational display on the history of the medical arts, to warn the public against the perils of quackery and the faults of folk medicine, as well as to expose evils in drug adulteration. Today, we can see actual fulfillment of these intentions in the present exhibit at the medical gallery which has been executed recently on the basis of scientific, historical research.
After Dr. Flint's retirement from the Smithsonian Institution in 1912, there was no replacement for over five years. Therefore, the Division of Medicine was placed, for administrative purposes, under the supervision of the curator of the newly reestablished (1912) Division of Textiles, Frederick L. Lewton. During these years, he fought against the dispersal of the medical and _materia medica_ collections. Thus, for lack of a curator of its own, almost all new activities in the Division of Medicine were curtailed until 1917.
On January 31, 1917, Lewton addressed members of the American Pharmaceutical Association inviting them to cooperate in gathering up and preserving at the National Museum the "many unique and irreplaceable objects" connected with the early history of pharmacy in this country which could still be saved.[10] Then, on March 14, 1917, an examination was announced by the Civil Service (held May 2) for an assistant curator for the Division of Medicine, and the position was filled by Joseph Donner on August 16, 1917. Donner was the first full-time employee paid by the Smithsonian Institution for the curatorship of this Division. He held the post until January 31, 1918, when he was inducted into the Sanitary Corps of the United States Army. No significant activities in the Division of Medicine were reported during these few months.
Mr. Donner was followed by a second, full-time, museum officer who promoted a great amount of good will towards the Division during his curatorship of a little over 30 years. Dr. Charles Whitebread (1877-1963), the first pharmacist to head the Division, joined the Smithsonian in 1918 and remained until his retirement in 1948, the longest service, thus far, of any individual in the Division.
Dr. Whitebread received his degree of Doctor of Pharmacy from the School of Pharmacy at George Washington University in Washington, D.C., in 1911. He entered government service late in 1915, but it was not until April 2, 1918, that he agreed to become assistant curator of the Division of Medicine.
Curator Whitebread's first year was an active and challenging one, for in this new position he began to develop a deep interest in the history of the healing arts. He made a number of important acquisitions, most of them pertaining to pharmaceutical products, synthetic chemicals and crude drugs. He found that many specimens from the older drug collections had deteriorated to such an extent as to be worthless, and he began replacing them with freshly marketed drugs.
Plans were completed for the opening of new medical exhibits and adopting, with some modifications and additions, earlier classifications set by Dr. Flint. Dr. Whitebread grouped these into the following classes: the evaluation of the healing arts; a picture display of medical men prominent in American history;[11] a _materia medica_ display including the history of pharmacy; and an exhibition on Sanitation and Public Hygiene[12] which was later to evolve into the Hall of Health.
In 1920, Dr. Whitebread added a number of specimens of medical-dosage forms and pharmaceutical preparations to the Division's collections. He also acquired other gifts to complete existing exhibits illustrating the basic principles of the various schools of medicine, such as homeopathy and osteopathy--their methods, tools, and ways of thought.
In 1921, a tablet machine by the Arthur Colton Company of Detroit, Michigan, was acquired, and an exhibit illustrating vaccine and serum therapy was installed in the medical gallery. This was followed, in 1922, by a collection arranged to tell the story of the prevention and cure of specific diseases by means of biological remedies.
During the following two years, two more exhibits related to hospital supplies and sanitation were added to the rapidly developing Hall of Health exhibition which was opened in 1924. A third exhibit in 1925 consisted of 96 mounted color transparencies illustrating services provided by hospitals to promote public health. Plans for the further development of the Hall of Health continued during 1926, and contacts were made with organizations interested in the educational aspects of the healing arts. As a result, several new exhibits were added. In 1926, the American Optometric Association helped in the installation of an exhibit on conservation of vision or the care of the eyes under the slogan "Save your vision," as a phase of health work. Other exhibits in the Hall at this time were: what parasites are; water pollution and how to obtain pure water; waste disposal; ventilation and healthy housing, and the importance of recreation; purification of milk and how to obtain pure milk; transmission of diseases by insects and animals; how life begins; prenatal and postnatal care and preschool care; duties of the public health nurse; and social, oral and mental hygiene.
With the acquiring of more medical appliances and the widening of the scope of the exhibits, more and more space was needed, and attention was turned to the area of the medical gallery which had been occupied by the _materia medica_ collection for almost four decades. To gain more exhibit space, it was decided that the greater part of the crude drugs should be removed from the exhibits and be kept as a reference collection and for research.[13]
In 1926, original patent models including those related to pharmacy, medicine, and dentistry, were transferred from the U.S. Patent Office to the National Museum. These patent models, together with other apothecary tools and the machines used in drug production took up most of the available space. This unfortunate situation led Dr. Whitebread to turn down significant medical and pharmaceutical collections offered the Museum between 1927 and 1930. Since the patent models were devised for inventions designed to simplify the practice of the health professions, three cases of these models were displayed in the medical gallery in the early 1930's. Other exhibits shown during this decade included the deception of folk medicine with warnings against superstitions, and an exhibition on osteopathy,[14] as well as dioramas on the manufacture of medicines and their use in scientific medical treatment.
In the meantime, Dr. Whitebread was an active contributor to the literature of the health field in various periodicals, as well as in pamphlets issued by the Museum and other governmental agencies (see bibliography). His literary contributions, guided by the exhibits he designed and the collections he acquired, were focused on the Division's collections, such as primitive and psychic medicine and warnings against reliance on magic and superstitions in treatment, medical oddities, and the utilization of drugs of animal origin, both past and present.
Division of Medicine and Public Health (1939-1957)
After taking charge of the Division of Medicine in 1918, Dr. Whitebread gave special attention to public health displays. His activities in this area were accelerated after 1924 when the health exhibit at the Smithsonian Institution was inaugurated. As the exhibits in this field increased, the Division, in 1939, took the more comprehensive title of Division of Medicine and Public Health. Also, in 1939, Dr. Whitebread was promoted to the rank of associate curator.
He continued his efforts to collect more specimens of interest to medical history and to contribute to the literature. Among exhibited specimens in 1941 were a powder paper-crimping machine, a portable drug crusher, an odd device for spreading plaster on cloth, a pill-coating apparatus, various suppository molds, a lozenge cutter, and an ingenious Seidlitz powder machine. The derivation of medicinal drugs from animal, vegetable, and mineral sources was also depicted, as were synthetic materials and their intermediates. Basic prescription materials were displayed, and rows of glass-enclosed cases held samples of crude botanical drugs from almost every part of the globe with explanatory cards giving brief, concise descriptions. The exhibition provided medical and pharmaceutical students about to take state-board examinations, the opportunity to study the subject in detail, especially the enormous collection of _materia medica_ samples.[15] Also in 1941, Eli Lilly and Company donated an exhibit on the medical treatment of various types of anemia. In the same year, a diorama including a hypochlorinator for purification of water on a farm was installed in the gallery. In 1942, the first Emerson iron lung (developed in 1931 by John Haven Emerson) for artificial respiration was acquired by the Division. The Division acquired, in 1944, the first portable x-ray machine known to have been operated successfully on the battlefield, as well as other x-ray equipment and early medicine chests.
Without a doubt, the most outstanding accession in the field of pharmaceutical history during Dr. Whitebread's years of service was the acquisition of the E. R. Squibb and Sons old apothecary shop. Most of the baroque fixtures, including the stained-glass windows with Hessian-Nassau coats of arms and wrought-iron frames, were part of the mid-18th-century cathedral pharmacy "Muenster Apotheke" in Freiburg im Breisgau, Germany. It was offered for sale in September 1930 by Dr. Jo Mayer of Wiesbaden, Germany, who was an enthusiastic collector of antiques, especially those related to the health professions. Earlier that year, a historian of pharmacy and chemistry, Fritz Ferchl of Mittenwald, Germany, had published a series of scholarly and informative articles on the Meyer collection in which the outstanding specimens were beautifully portrayed and thoroughly described (see bibliography).
As a result of Dr. Mayer's efforts to sell his collection, the impact of Ferchl's illustrated articles, and the uniqueness of the collection, E. R. Squibb and Sons purchased it in 1932 and brought it to the United States "with the thought that it would provide for American pharmacy, its teachers and students, a museum illuminating the history, growth, and development of pharmacy, its interesting background and struggle through the ages." It was displayed at the Century of Progress exposition held in Chicago during 1933 and 1934; subsequently, it was assembled in the Squibb Building in New York City as a private museum where, for about 10 years, it was visited by many interested in pharmacy, ceramics, and art. Charles H. LaWall, who was originally engaged to prepare a descriptive catalog on the exhibit, gave it the title "The Squibb Ancient Pharmacy."
Late in 1943, E. R. Squibb and Sons offered the collection as a gift to the American Pharmaceutical Association if the latter would provide museum space for it. The offer was accepted, but the Association finally found it difficult to spare the needed space for the collection and decided to take up the matter with the U.S. National Museum.
At this point, it should be stated that since 1883 the members of the American Pharmaceutical Association have been keenly interested in having the National Museum serve as the custodian for all collected objects and records of historical interest to pharmacy. In 1944, the Association officially offered to deposit on permanent loan, the Squibb's pharmacy collection in the Smithsonian Institution with the understanding that a suitable place would be provided for prompt and permanent display. The offer was accepted, and during April and May of 1945, the entire collection was transferred to the Smithsonian Institution, and construction to recreate the original two rooms for the old, 18th-century, European "Apotheke" was underway.
By August 1946, the exhibit was completed. In the large room where the pharmacist met his customers, the shelves were filled with 15th-to 19th-century, European pharmaceutical antiques. These included Renaissance mortars; 16th-and 17th-century nested weights; beautiful Italian, French, Swiss, and German majolica and faience drug jars; Dutch and English delft; drug containers made of flint or opal glass with fused-enamel labels with alchemical symbols; rare, 16th-century, wooden drug containers, each with the coat of arms of the city in which each was made; and two glass-topped, display tables contained franchises issued and signed by Popes or state rulers, medical edicts, dispensatories, herbals, pharmacopoeias, and pharmaceutical utensils.
On the walls in the small laboratory room, which also had been used as a workshop and a study, were a stuffed crocodile, shark's head, tortoise, fish, and salamander, parts of which were utilized as remedial agents. Their presence provided tangible evidence that the pharmacy dispensed genuine drugs and not substitutes.
The pharmaceutical profession in this country hailed the outstanding exhibition, and the November 1946 issue of the _Journal of the American Pharmaceutical Association, Practical Pharmacy Edition_, devoted its front cover to depicting one corner of the study and laboratory room of the shop.[16] Also, in a letter dated January 2, 1947, addressed to Dr. Alexander Wetmore, then Secretary of the Smithsonian Institution, Dr. Robert P. Fischelis, the secretary of the American Pharmaceutical Association, considered the completion of the deposited exhibition a triumph and "as one of the highlights of the accomplishments of the Association in 1946."
From 1946 to 1948, the Division's collection was further enriched with a number of historical specimens, among which was a "grosse Flamme" x-ray machine with induction-coil tube and stand developed by Albert B. Koett. It is one of the earliest American-made machines of its kind, producing a 12-inch spark, the largest usable at that time with 180,000-volt capacity, and a forerunner of later autotransformers. Other accessions included two 19th-century drug mills, an electric belt used in quackery, two medicine chests, three sets of Hessian crucibles used in a pioneer drugstore in Colorado, a drunkometer, mineral ores, and purely produced chemical elements.
In the spring of 1948, Associate Curator Whitebread retired after 30 years of service with the U.S. National Museum. He was a pioneer in the field of health museums and during his curatorship had developed a moribund section into a Division of field-wide importance. Dr. Whitebread was succeeded by George S. Thomas, also a pharmacist, who served as associate curator from August 1948 until early 1952.
During his almost-three and a half years of service, Thomas acquired hearing-aid appliances from which he designed an exhibit on the development of these aids, surgical sutures, early samples of Aureomycin, and a static-electricity machine made by Henkel about 1840. He also published three short articles under the title, "Now and Then," in the _National Capital Pharmacist_ (1950), no. 1, pp. 8-9; no. 2, pp. 18-19, 29; and no. 3, pp. 15-16. In early 1952, Dr. Arthur O. Morton presented to the Division, a Swiss-made keratometer which he had purchased in 1907, and it is believed to be one of the first used in the United States to measure the curves of the cornea.
The achievements of the Division reached their highest point, thus far, in significantly increasing the national collection, as well as in contributing to the scientific, historical, and professional literature, under the curatorships of George B. Griffenhagen (December 8, 1952, to June 27, 1959) and John B. Blake (July 1, 1957, to September 2, 1961). Their reorganization of exhibits and collections, their competence and industry, fulfilled the hopes, plans, and purposes laid down by earlier curators for the Division.
Immediately after assuming the responsibilities of the Division and throughout 1953, Mr. Griffenhagen (M.S. in pharmaceutical chemistry from the University of Southern California) undertook to develop the collections still further. He increased the emphasis not only on historical pharmacy, but also on medicine, surgery, and dentistry. He also renovated the exhibits in the medical gallery.
In 1954, several antibiotics were donated to the Division including a mold of _Penicillium notatum_ prepared and presented to the Smithsonian Institution by Sir Alexander Fleming (1881-1955), the discoverer of penicillium (1929), and a few Petri dishes used by botanist Benjamin M. Daggar who, while working for Lederle Laboratories, developed Aureomycin (chlortetracycline) in 1948. The Forest D. Dodrill--G.M.R. mechanical heart (1952), the first machine reported to be used successfully for the complete bypass of one side of the human heart during a surgical operation,[17] was presented to the Smithsonian Institution.
The following year, 1955, the Division acquired one of the earliest Einthoven string galvanometers (named after the Dutch physiologist Willem Einthoven, 1860-1927) made in the United States in 1914 by Charles F. Hindle for an electrocardiograph. Also added to the Division's collections was the electrocardiograph used by Dr. Frank E. Wilson of the United States, a pioneer educator in this field. Two temporary exhibits on allergy and surgical dressings were installed in the gallery. In the same year, Curator Griffenhagen published _Early American Pharmacies_, a catalog on 28 pharmacy restorations in this country.
In 1956, among many publications of interest in the fields of medical and pharmaceutical history, was Curator Griffenhagen's _Pharmacy Museum_, with a foreword by Laurence V. Coleman, who termed it a useful catalog and "a good reflection of the history of the museum movement at large." A third x-ray tube of Wilhelm Konrad Roentgen (1845-1922) was added to the collection in 1957 as well as a complete set of hospital-ward fixtures of about 1900 from the Massachusetts General Hospital, rare patent medicines, 18th-century microscopes, and a 13th-century mortar and pestle made in Persia.
In 1957, Mr. Griffenhagen published a series of illustrated articles in the _Journal of the American Pharmaceutical Association, Practical Pharmacy Edition_, which were later reprinted by the Association in a booklet entitled, _Tools of the Apothecary_. In it, he described several pharmaceutical specimens in the collection and their place in history.
Division of Medical Sciences (1957 to Present)
The U.S. National Museum was reorganized on July 1, 1957, into two units, the Natural History Museum and the Museum of History and Technology. At the same time, and in view of the widening scope of the Division, its more scientifically based planning, and the constantly increasing collection with equal emphasis on all branches of the healing arts, the Division's title was changed to the Division of Medical Sciences--the title it still bears in 1964. With the reorganization, the Department of Engineering and Industries, under which the Division fell administratively, was renamed the Department of Science and Technology of the Museum of History and Technology. It was also the first time since its establishment in 1881 that the Division had two curators, for on July 1, 1957, Dr. John B. Blake joined the staff.
As a result of these changes, the Division was subdivided into a Section of Pharmaceutical History and Health and a Section of Medical and Dental History. The former was planned to encompass the collections of _materia medica_, pharmaceutical equipment, and all material related to the history of pharmacy, toxicology, pharmacology, and biochemistry, as well as the Hall of Health which was opened November 2, 1957, and which emphasizes man's progressing knowledge of his body and the functions of its major organs.[18] The latter Section was planned to include all that belongs to the development of surgery, medicine, dentistry, and nursing, especially in relation to hospitals.
In October 1957, the Division acquired a collection of rare, ceramic, drug jars which included two, 13th-century, North Syrian and Persian, albarello-shaped, majolica jars; a 15th-century, Hispano-Moresque drug container; and a 16th-century, Italian faience, dragon-spout ewer. During the following two years, Curator Griffenhagen periodically toured museums and medical and pharmaceutical institutions in this country, South America, and Europe gathering specimens and information for the Division and for publication, respectively. However, on June 27, 1959, he resigned his curatorship to join the staff of the American Pharmaceutical Association in Washington, D.C. Dr. Blake became the curator in charge of the Division and Mr. Griffenhagen was succeeded on September 24, 1959, by the author of this paper as associate curator in charge of the Section of Pharmaceutical History and Health.
Dr. Blake, as curator of the Section of Medical and Dental History, acquired a large number of valuable and varied specimens for the Division's collections. They included optometric refracting instruments, an early 1920's General Electric, portable, x-ray machine, the Charles A. Lindbergh and Alexis Carrel pump (designed in 1935 to perfuse life-sustaining fluids to the organs of the body), the Sewell heart pump (1950) to control delivery of air pressure and suction to the pumping mechanism, and a large and valuable collection of dental equipment formerly at the universities of Pennsylvania and Illinois. Dr. Blake wrote the explanatory material and supervised the design and production of the majority of exhibits in the renovated hall of medical and dental history. He also contributed several scholarly articles and a book (see bibliography) on the history of the healing arts and public health in particular. He resigned on September 2, 1961, to join the staff of the National Library of Medicine as chief of the History of Medicine Division, and was succeeded by the author as curator of the Division. From the summer of 1962 to April 1964, the Division benefited from the expert advice of Dr. Alfred R. Henderson as consultant in the preparation and designing of the surgical and medical exhibits of the Museum of History and Technology.
During the period from 1961 to May 1964, the Division's collections expanded greatly through its medical, dental, and pharmaceutical acquisitions. Specimens of antiques acquired from 1961 through 1963 numbered up to 1,539 and included gifts from leading institutions and individual philanthropists. The scope of these gifts and acquisitions ranges from electronic resuscitators, microscopes, x-ray equipment, and spectacles, to patent medicines, amulets, apothecary tools, dental instruments, and office material of practitioners.
In the last decade, the interest in the national endeavor for promoting research and scholarship in the history of medicine has increased greatly. It was most appropriate, therefore, for the Smithsonian Institution to play host on May 2 for two sessions of the 37th annual meeting of the American Association for the History of Medicine held in the Washington, D.C., area from April 30 through May 2, 1964. In welcoming the members to the morning session in the auditorium of the new Museum of History and Technology, Frank A. Taylor, director of the United States National Museum, expressed the feeling that the meeting of the Association was, in a sense, a dedication of the new auditorium and an opportunity for the Smithsonian to reaffirm its deep interest and commitment in fostering research and furthering the appreciation of scholarly endeavor in the history of the healing arts.
A New Dimension For the Healing Arts
"One day the United States will have a National Museum of science, engineering, and industry, as most large nations have." This was the prediction made in 1946 by the director of the U.S. National Museum, Mr. Frank A. Taylor, then curator of the Division of Engineering.[19] It was in 1963, that the new $36,000,000 building of the Museum of History and Technology was completed, and opened to the public in 1964. The offices of the Division of Medical Sciences as well as the reference and study collections were moved to the fifth floor of the new building. The exhibits, however, will be displayed in the gallery at the southwest corner of the first floor. These exhibits, it is hoped, will show a new dimension and an unprecedented approach in displaying the development of the healing arts throughout the ages and the instruments and equipment associated with health professions. They also present the expanding objectives and plans of the Division's growth as an integral part of the Smithsonian Institution. Conveniently, the exhibits form four, closely connected halls in one large gallery which will be open to the public in the summers of 1965 to 1966.
1. THE HALL OF HEALTH displays models and graphic and historical exhibit materials to demonstrate the function of the various healthy organs of the human body. The main topics emphasized are: embryology and childbirth; tooth structure; the heart and blood circulation; respiration; the endocrine glands; kidneys and the urinary-excretory system; the brain and the nervous system; the ear; and vision and the use of eyeglasses.
The most appreciated exhibit of all in this Hall is the "transparent woman" figure which rotates, automatically, every 15 minutes with a recorded message describing the function of each major organ of the body at the same time that the organ is electronically lighted, so that the viewer can see its place in the body.
2. THE HALL OF MEDICINE AND DENTISTRY will depict the history of these two sciences with exhibits of the equipment used through the centuries. In the medical field, early trephining and other surgical instruments will be displayed along with a diorama of an 1805 surgical operation performed by Dr. Philip Syng Physick in the amphitheater of the Pennsylvania Hospital. Diagnostic instruments such as stethoscopes, endoscopes, speculums, and blood-pressure measuring devices will be exhibited with a series of microscopes illustrating the development of these instruments. Exhibits of original galvanometers and other apparatus will trace the development of cardiography. The early use of anesthesia will be shown by apparatus of William Morton and Crawford W. Long, American pioneers in this field. The development of the devices of modern medicine and surgery will be shown by exhibits of the iron lung and x-ray tubes, including a tube used by W. K. Roentgen. Medicine chests and surgical kits of different periods will graphically summarize the state of medical science in the period each represents.
Exhibits on the development of dentistry and dental surgery will display examples of tooth-filling and extracting tools, drilling apparatus from the early hand and foot engines to the first ultrasonic cutting instrument (1954), and the original contra-angle, hydraulic and air-turbine handpiece model[20] which revolutionized the field of instrumentation for dental surgery (with speeds of 200,000 to 400,000 rpm). This hydraulic turbine of Dr. Robert J. Nelson and associates of the National Bureau of Standards set the design pattern for the remarkable and successful high-speed, air-turbine handpiece developed by Paul H. Tanner and Oscar P. Nagel of the U.S. Naval Dental School in 1956. Also underway is the reconstruction of the offices of famous dentists such as G. V. Black and the father of American orthodontia, Edward H. Angle, using their original equipment and instruments. In addition, an exhibit is planned to include x-ray tubes and the electric dental engine, the first to be operated in a human mouth by the pioneer dentist on dental skiagraphy, Charles E. Kells (1856-1928).[21]
3. THE HALL OF PHARMACEUTICAL HISTORY will feature exhibits on the reconstruction of two pharmacy shops: an 18th-century apothecary shop, originally from Germany, with a very elegant collection of drug jars, decorated medicinal bottles, balances, mortars and pestles, and other tools and documents pertaining to the apothecary art, and a late 19th-century American drugstore with shelves filled with patent medicines and drug containers of various sizes and shapes. The window will also feature symbols of pharmacy and beautiful show globes. Displays will show the development of antibiotics and the early tools used in the manufacture of the so-called "miracle drugs," including a mold from Sir Alexander Fleming, the discoverer of penicillin. In addition, a platform will be reconstructed to display a variety of pharmaceutical apparatus used in the preparation and manufacture of drugs, such as tablet and capsule machines and drug mills and percolators. Recently, with the assistance of Professor Glenn Sonnedecker, the Division acquired a fine collection of pharmaceutical equipment and devices from the School of Pharmacy of the University of Wisconsin.
Since the Division houses the largest collection of _materia medica_ in the country, a representative cross section of crude drugs will be displayed in alphabetical order as well as a display illustrating the role of cinchona and antimalarial drugs in the fight against disease. An exhibit will portray the "origin of drugs" from the three natural kingdoms, animal, vegetable, and mineral, together with synthetic drugs including the manufacture of vitamins.
Plans are being made for an elaborate exhibit of weights and balances used in many countries throughout the centuries, their impact on accuracy of dosage and weighing of drugs, and their use in the apothecary art.
The Division will also display pictorial and printed materials, as well as artifacts from all periods and all countries. These collections are intended to help in presenting a more complete picture of the story of the medical sciences for educational purposes and research, and to increase man's knowledge in fighting disease and promoting health.
Thus, from a few hundred specimens of crude drugs in the Section of Materia Medica of 83 years ago, there has developed a Museum Division today which embraces the evolution of the health professions through the ages. This Division now has the largest collection in the Western Hemisphere of historical objects which are related to the healing arts. The reference collections are available to the researcher and scholar, and the exhibits are intended for pleasure and educational purposes in these fields. The plans for expansion have no limitation as we keep pace with man's progress in the medical sciences and continue to collect materials that contributed to the historical development in the fight against diseases and the attempts to secure better health for everyone.
BIBLIOGRAPHY
The _Annual report of the Board of Regents of the Smithsonian Institution_ from 1872 to date and the _Proceedings of the United States National Museum_ from 1881 to date were used extensively as sources in this survey. In the latter, see in particular, the year 1881, pp. 545-546; 1882, pp. 1-2; and 1884, pp. 431-475.
ATKINSON, WILLIAM B. _The physicians and surgeons of the United States._ Philadelphia, 1878. [On Dr. Toner.]
BLAKE, JOHN B. Dental history and the Smithsonian Institution. _Journal of the American College of Dentists_ (1961), vol. 28, pp. 125-127.
---- _Public health in the town of Boston, 1630-1822._ Cambridge, Mass.: Harvard University Press, 1959.
[BRAISTED, WILLIAM C.] The biography of Dr. Beyer. Page 94 in _Dictionary of American medical biography_, by HOWARD A. KELLY and WALTER L. BURRAGE; NEW YORK: D. Appleton and Co., 1928.
CLARK, LEILA F. The library of the Smithsonian Institution. _Science_ (1946), vol. 104, p. 143.
COLEMAN, LAURENCE VAIL. _The museum in America: A critical study._ 3 vols. Baltimore: Waverly Press, 1939. [Printed for the American Association of Museums, Washington, D.C.] See vol. 1, pp. 3, 11-12, 32-33, 143-146, 222, 318; vol. 3, p. 471.
DAUKES, S. H. _The medical museum: modern developments, organization and technical methods based on a new system of visual teaching._ London: Wellcome Foundation Ltd., 1929.
DODRILL, FOREST D., and others. Pulmonary volvuloplasty under direct vision using the mechanical heart for a complete bypass of the right heart in a patient with congenital pulmonary stenosis. _Journal of Thoracic Surgery_ (1953), vol. 26, pp. 584-595.
---- Temporary mechanical substitution for the left ventricle in man. _Journal of the American Medical Association_ (1952), vol. 150, pp. 642-644.
DUNGLISON, ROBLEY. _A dictionary of medical science._ Rev. ed. Pp. 629-630. Philadelphia: Lea, 1874.
EDWARDS, J. J., and EDWARDS, M. J. _Medical museum technology._ London: Oxford University Press, 1959. [See in particular, pp. 33-62, 142-159.]
FERCHL, FRITZ. Die Moerser der Sammlung Jo Mayer--Wiesbaden; Libri rari et curiosi der Sammlung Dr. Jo Mayer--Wiesbaden; Bildnisse und Bilder der Sammlung Jo Mayer--Wiesbaden; Kuriositaeten und Antiquitaeten der Sammlung Jo Mayer--Wiesbaden; and Glaeser, Majoliken und Faensen der Sammlung Jo Mayer--Wiesbaden. _Pharmazeutische Zeitung_ (Berlin, 1930), vol. 75: January 4, no. 2, pp. 19-24; February 15, no. 14, pp. 219-223; March 8, no. 20, pp. 309-314; April 19, no. 32, pp. 487-489; and June 21, no. 50, pp. 735-740.
FLINT, JAMES M. Classification and arrangement of the materia medica collection. _Proceedings of the United States National Museum_ (1881), vol. 4, app. no. 6.
---- Classification of the materia medica collection of the United States National Museum, and catalogue of specimens. _Proceedings of the United States National Museum_ (1883), vol. 6, app. 19, pp. 431-475.
---- Directions for collecting information and objects illustrating the history of medicine. Part S of _Bulletin of the United States National Museum_ (1905). No. 39.
---- Memoranda for collectors of drugs for the materia medica section of the National Museum. _Proceedings of the United States National Museum_ (1881), vol. 4, app. 8.
FOLEY, MATTHEW O. Smithsonian Institution devotes much space to hospital exhibit. _Hospital Management_ (April 1929), pp. 271-287.
GALDSTON, IAGO. Research in the United States. _Ciba Symposia_ (June-July 1946), vol. 8, nos. 3 and 4, p. 366.
GARRISON, FIELDING H. _An introduction to the history of medicine._ 2d ed. p. 38. Philadelphia: Saunders, 1917.
GEBHARD, BRUNO. From medicine show to health museum. _Ciba Symposia_ (March 1947), vol. 8, no. 12, p. 579.
GOODE, GEORGE BROWN. _The Smithsonian Institution (1846-1896): The history of its first half century._ Pp. 325-329, 362-363. Washington, 1897.
GRIFFENHAGEN, GEORGE. _Pharmacy museums._ Madison, Wis.: American Institute of the History of Pharmacy, 1956.
---- and HUGHES, CALVIN H. The history of the mechanical heart. _Annual report of the Board of Regents of the Smithsonian Institution for the year ended June 30, 1955_ (Washington, 1956), pp. 339-356.
HAMARNEH, SAMI. At the Smithsonian ... exhibits on pharmaceutical dosage forms. _Journal of the American Pharmaceutical Association_ (1962), new ser., vol. 2, pp. 478-479.
----For the collector, facts and artifacts. _Pharmacy in History_ (1961), vol. 6, p. 48.
---- Historical and educational exhibits on dentistry at the Smithsonian Institution. _Journal of the American-Dental Association_ (July 1962), vol. 65, pp. 111-114.
---- New dental exhibits at the Smithsonian Institution. _Journal of the American Dental Association_ (May 1963), vol. 66, pp. 676-678.
HAYNES, WILLIAM. Out of alchemy into chemistry. _The Scientific Monthly_ (November 1952), vol. 75, p. 268.
HOLT, L. EMMETT. A sketch of the development of the Rockefeller Institute for Medical Research. _Science_ (July 6, 1906), new ser., vol. 24, no. 601, p. 1.
HOWELL, WILLIAM H. The American Physiological Society during its first twenty-five years. Pp. 21-22 [biography of Dr. Beyer] in _History of the American Physiological Society semicentennial, 1881-1937_; Baltimore, 1938.
[KLEIN, ALLEN.] He directs pharmacy exhibits at the Smithsonian Institution. _Modern Pharmacy_ (July 1941), vol. 25, pp. 20-21.
LAWALL, CHARLES H. Ancient pharmacy on display. _Pacific Drug Review_ (1933), vol. 45, p. 18.
---- _The curious lore of drugs and medicines._ Garden City, N.Y.: Garden City Publishing Co., Inc., 1927. [See p. 453 on Division of Medical Sciences' collection.]
LEWTON, FREDERICK L. A national pharmaceutical collection. _Journal of the American Pharmaceutical Association_ (1919), vol. 8, pp. 45-46.
---- The opportunity for developing historical pharmacy collections at the National Museum. _Journal of the American Pharmaceutical Association_ (1917), vol. 6, pp. 259-262.
LONG, ESMOND R. The Army Medical Museum. _Military Medicine_ (May 1963), vol. 128, pp. 367-369.
MONELL, S. H. "Dental Skiagraphy" (pp. 313-336 in _A system in x-ray methods and medical uses of light hot-air, vibration and high-frequency currents_ by Monell; New York: Pelton, 1902).
MURRAY, DAVID. _Museums, their history and their use._ Glasgow: MacLehose, 1904. [See vol. 1, pp. 13-77.]
NELSON, ROBERT J.; PELANDER, CARL E.; and KUMPULA, JOHN W. Hydraulic turbine, contra-angle handpiece. _Journal of the American Dental Association_ (September 1953), vol. 47, pp. 324-329.
_Official Catalogue of the Cotton States and International Exposition_: Atlanta, Georgia, September 18 to December 31, 1895. Atlanta: Claflin and Mellichamp, 1895. [See p. 204.]
PACKARD, FRANCES R. _History of medicine in the United States._ New York, 1931. [See vol. 1, pp. 5-6, 37-51, 168-176, 602-607 on Dr. Toner.]
PICKARD, MADGE E. Government and science in the United States: Historical background. _Journal of the History of Medicine and Allied Sciences_ (1946), vol. 1, nos. 2 and 3, pp. 265-266, 289, 446-447, 478.
PURTLE, HELEN R. Notes on the Medical Museum of the Armed Forces Institute of Pathology. _Bulletin of the Medical Library Association_ (1956), vol. 44, no. 3, pp. 300-305.
RATHBUN, RICHARD. _A descriptive account of the building recently erected for the Departments of Natural History of the United States National Museum._ (U.S. National Museum Bulletin 80.) Washington, 1913. [See pp. 7-15.]
RHEES, WILLIAM J. _The Smithsonian Institution; documents relative to its origin and history, 1835-1899._ 2 vols. (Smithsonian Miscellaneous Collections: vol. 42, _1835-1881_; vol. 43, _1881-1899_.) Washington, 1901.
SHUFELDT, R. W. Suggestions for a national museum of medicine. _Medical Record_ (March 22, 1919), pp. 4-5. [Also reprinted, 1919, by William Wood and Co., New York.]
SIGERIST, HENRY E. _Primitive and archaic medicine._ (Vol. 1 of _A history of medicine_, by Sigerist.) New York: Oxford University Press, 1951. [See pp. 525-531.]
SILVER, EDWIN H. Description of the exhibit on conservation of vision placed in the United States Museum at Washington, D.C. _The Optical Journal and Review of Optometry_ (February 3, 1927), vol. 59, no. 5, pp. 39-40.
[SONNEDECKER, GLENN.] Apothecary shop nears completion. _Journal of the American Pharmaceutical Association, Practical Pharmacy Edition_ (1946), vol. 7, pp. 157.
---- Dr. Charles Whitebread, pharmacist and museum curator. _Journal of the American Pharmaceutical Association, Practical Pharmacy Edition_ (1946), vol. 7, p. 203.
---- Old apothecary shop. _Journal of the American Pharmaceutical Association, Practical Pharmacy Edition_ (1945), vol. 6, pp. 184-187.
---- Old apothecary shop opened. _Journal of the American Pharmaceutical Association, Practical Pharmacy Edition_ (1946), vol. 7, p. 427.
TAYLOR, FRANK A. A national museum of science, engineering and industry. _The Scientific Monthly_ (1946), vol. 63, pp. 359.
---- The background of the Smithsonian's Museum of Engineering and Industries. _Science_ (1946), vol. 104, no. 2693, pp. 130-132.
Toner Lectures:
1. J. J. WOODWARD. On the structure of cancerous tumors and the mode in which adjacent parts are invaded. No. 266 in _Smithsonian Miscellaneous Collections_, vol. 15; Washington, 1878. [Lecture given on March 28, 1873.]
2. C. E. BROWN-SEQUARD. Dual character of the brain. No. 291 in _Smithsonian Miscellaneous Collections_, vol. 15; Washington, 1878. [Lecture given on April 22, 1874.]
3. J. M. DA COSTA. On strain and over-action of the heart. No. 279 in _Smithsonian Miscellaneous Collections_, vol. 15; Washington, 1878. [Lecture given on May 14, 1874.]
4. H. C. WOOD. A study of the nature and mechanism of fever. No. 282 in _Smithsonian Miscellaneous Collections_, vol. 15; Washington, 1878. [Lecture given on January 20, 1875.]
5. WILLIAM W. KEEN. On the surgical complications and sequels of the continued fevers. No. 300 in _Smithsonian Miscellaneous Collections_, vol. 15; Washington, 1878. [Lecture given on February 17, 1876.]
6. WILLIAM ADAMS. Subcutaneous surgery: Its principles, and its recent extension in practice. No. 302 in _Smithsonian Miscellaneous Collections_, vol. 15; Washington, 1878. [Lecture given on September 13, 1876.]
7. EDWARD O. SHAKESPEARE. The nature of reparatory inflammation in arteries after ligatures, acupressure, and torsion. No. 321 in _Smithsonian Miscellaneous Collections_, vol. 16; Washington, 1880. [Lecture given on June 27, 1878.]
8. GEORGE E. WARING. Suggestions for the sanitary drainage of Washington City. No. 349 in _Smithsonian Miscellaneous Collections_, vol. 26; Washington, 1883. [Lecture given on May 26, 1880.]
9. CHARLES K. MILLS. Mental over-work and premature disease among public and professional men. No. 594 in _Smithsonian Miscellaneous Collections_, vol. 34; Washington, 1893. [Lecture given on March 19, 1884.]
10. HARRISON ALLEN. A clinical study of the skull. No. 708 in _Smithsonian Miscellaneous Collections_, vol. 34; Washington, 1893. [Lecture given on May 29, 1889.]
TRUE, WEBSTER P. _The Smithsonian Institution._ (Vol. 1 of the Smithsonian Scientific Series.) Washington, 1929.
URDANG, GEORGE, and NITARDY, F. W. _The Squibb ancient pharmacy._ New York, 1940. [Out of print, but remaining catalogs were given to the Division of Medicine to "be reserved for pharmaceutical educators, foreign dignitaries, pharmacists of national and international reputation, and pharmaceutical historians," according to a letter from Mr. Nitardy in 1945.]
WHITEBREAD, CHARLES. Animal pharmaceuticals of the past and present. _Journal of the American Pharmaceutical Association_ (1933), vol. 22, pp. 431-437.
---- An old apothecary shop of 1750. _National Capital Pharmacist_ (September 1946), vol. 8, pp. 11-13, 35.
---- Early American pharmaceutical inventions. _Journal of the American Pharmaceutical Association_ (1937), vol. 26, pp. 918-928.
---- _Handbook of the health exhibits of the United States National Museum._ Baltimore: Lord Baltimore Press [1924].
---- Health superstitions. _Journal of the American Pharmaceutical Association, Practical Pharmacy Edition_ (1942), vol. 3, pp. 268-274.
---- Medicine making as depicted by museum dioramas. _Journal of the American Pharmaceutical Association_ (January 1936), vol. 25, pp. 40-46.
---- Superstition, credulity and skepticism. _Journal of the American Pharmaceutical Association_ (1933), vol. 22, pp. 1140-1145.
---- The Indian medical exhibit of the Division of Medicine in the United States National Museum. Article 10 in vol. 67 of _Proceedings of the U.S. National Museum_; Washington, 1926.
---- The magic, psychic, ancient Egyptian, Greek, and Roman medical collections of the Division of Medicine in the United States National Museum. Article 15 in vol. 65 of _Proceedings of the U.S. National Museum_; Washington, 1925.
---- The odd origin of medical discoveries. _Journal of the American Pharmaceutical Association, Practical Pharmacy Edition_ (1943), vol. 4, p. 321.
---- The United States National Museum pharmaceutical collection, its aims, problems, and accomplishments. _Journal of the American Pharmaceutical Association_ (1930), vol. 19, pp. 1125-1126.
WINTERS, S. R. Magic medicine. _Hygeia_ (July 1937), vol. 15, pp. 630-633.
* * * * *
FOOTNOTES
[1] _Annual Report of the Board of Regents of the Smithsonian Institution for the Year 1882_ [hereinafter referred to as the _Smithsonian Annual Report_], pp. 101-103; and introductory "advertisement" to the lectures published by the Smithsonian Institution in its Miscellaneous Collections (see bibliography).
[2] Dr. J. J. Woodward's lecture explained the progress of medical knowledge of morbid growth and cancerous tumors from 1865 to 1872. It cautioned that uncertain methods of diagnosis at that time allowed charlatans and uneducated practitioners to report cures of cancer in instances where nonmalignant growths were "removed by their caustic pastes and plasters."
[3] The two longest intervals were in preparing the last two lectures: the ninth in 1884, and the tenth, 1889. Both came after the establishment in 1881 of the Section of Materia Medica in the U.S. National Museum, to display the development and progress of the health professions.
[4] _Annual Report of the Secretary of the Navy for the year 1883_, pp. 190, 614-615.
[5] For classifying chemical compounds, Dr. Flint relied on the work of H. E. Roscoe and C. Schorlemmez, _A Treatise on Chemistry_, 2 vols. (New York: D. Appleton, 1878-1800.)
[6] _Annual Report of the Secretary of the Navy for the year 1882_, vol. 2, part 2, pp. 100, 228, 656-657. Dr. Flint in his article "Report on Pharmacopoeias of All Nations," ibid., pp. 655-680, remarks that there were then 19 official pharmacopoeias in the world, besides three semiofficial formularies in certain localities in Italy. The pharmacopoeias collected represent Austria, Belgium, France, Germany, Great Britain, Greece, Holland, India, Mexico, Norway, Portugal, Spain, Sweden, Switzerland (two), and the United States.
[7] The _Universal Formulary_, by R. Eglesfeld Griffith, first edited in March 1850 (3rd ed. rev. and enlarged by John M. Maisch, Philadelphia: Lea, 1874) should not be considered an international drug standard. It was mainly concerned with compiling a great number of formulas and recipes, methods of preparing and administering official and other medicines, and tables on weights and measures for utilization by the U.S. practitioners of the time.
[8] Other elaborate arrangements were also made to improve and expand the Section's activities and services, though some have never materialized. For example, a herbarium was suggested from which specimens could be obtained for display of the actual drug with painted pictures of its plant next to it. Consideration was given to displaying enlarged drawings to show the minute structure of the specimen for better identification. In addition, an exhibition of several 10-liter vessels of the most popular mineral waters was planned. The amount of saline substances which analysis had shown to be present in each vessel was to be listed in a table to be attached to that vessel, or the same amount of minerals was to be put in a small bottle beside it. This plan was carried out to the best advantage at the Cotton States and International Exposition held in 1895 in Atlanta, Georgia.
[9] HOLT, "A Sketch of the Development of the Rockefeller Institute for Medical Research," p. 1. A similar comment was voiced by GALDSTON, "Research in the United States," p. 366.
[10] _Journal of the American Pharmaceutical Association_ (1918), vol. 7, pp. 376-377, 466.
[11] Two decades later, Dr. Whitebread designed a panel showing photographs of famous medical pioneers of all nationalities. See his article, "The Odd Origin of Medical Discoveries," p. 321.
[12] GEBHARD, "From Medicine Show to Health Museum," p. 579. The original plan for this Hall of Health was to feature exhibits on public health for popular educational purposes, including an illustrated exhibit on hospital care. See FOLEY, "Smithsonian Institution Devotes Much Space to Hospital Exhibit," pp. 43-44.
[13] Lack of space notwithstanding, valuable accessions were added about 1930, including a collection of early x-ray tubes and personal memorabilia of Drs. William T. G. Morton (1819-1868), Crawford W. Long (1815-1878), and William Gorgas (1854-1920).
[14] D. RILEY MOORE published a series of short reports under the title "Committee on Osteopathic Exhibits in the U.S. National Museum," in the _Journal of the American Osteopathic Association_ (1933-1946), vols. 33-46, regarding the exhibit on osteopathy.
[15] [KLEIN], "He Directs Pharmacy Exhibits at the Smithsonian Institution," pp. 20-21.
[16] Several other journals reported the exhibition with illustrations: _Drug Topics_ (July 8, 1946), vol. 90, no. 2, pp. 2, 79; _National Capital Pharmacist_ (September 1945), vol. 7, p. 11, and (September 1946), vol. 8, pp. 11-13; and _The Scientific Monthly_ (November 1952), vol. 75, p. 268.
[17] DODRILL, and others, "Temporary Mechanical Substitution for the Left Ventricle in Man," pp. 642-644, and "Pulmonary Volvuloplasty under Direct Vision using the Mechanical Heart for a Complete Bypass of the Right Heart in a Patient with Congenital Pulmonary Stenosis," pp. 584-595.
[18] For the design, expert arrangement of the exhibits, and the legends that accompany each exhibit in the Hall of Health, we are indebted to Drs. Bruno Gebhard, Richards H. Shryock, Thomas G. Hull, James Laster, Walle J. H. Nauta, Leslie W. Knott, Theodore Wiprud, and other physicians, dentists, and scholars who have offered their advice, assistance, and expert skills.
[19] TAYLOR, "A National Museum of Science, Engineering and Industry," p. 359.
[20] NELSON, PELANDER, and KUMPULA, "Hydraulic Turbine, Contra-angle Handpiece," pp. 324-329.
[21] MONELL, "Dental Skiagraphy," pp. 313-336.
* * * * *
Paper 43 - Transcriber's Note
Page 277: "the basis of scientific, historical" was "the bases of scientific, historical"
* * * * *
CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY:
PAPER 44
DEVELOPMENT OF GRAVITY PENDULUMS IN THE 19TH CENTURY
by
Victor F. Lenzen and Robert P. Multhauf
GALILEO, HUYGENS, AND NEWTON 304
FIGURE OF THE EARTH 306
EARLY TYPES OF PENDULUMS 309
KATER'S CONVERTIBLE AND INVARIABLE PENDULUMS 314
REPSOLD-BESSEL REVERSIBLE PENDULUM 320
PEIRCE AND DEFFORGES INVARIABLE, REVERSIBLE PENDULUMS 327
VON STERNECK AND MENDENHALL PENDULUMS 331
ABSOLUTE VALUE OF GRAVITY AT POTSDAM 338
APPLICATION OF GRAVITY SURVEYS 342
SUMMARY 346
_Victor F. Lenzen and Robert P. Multhauf_
DEVELOPMENT OF GRAVITY PENDULUMS IN THE 19th CENTURY
_The history of gravity pendulums dates back to the time of Galileo. After the discovery of the variation of the force of gravity over the surface of the earth, gravity measurement became a major concern of physics and geodesy. This article traces the history of the development of instruments for this purpose._
THE AUTHORS: _Victor F. Lenzen is Professor of Physics, Emeritus, at the University of California at Berkeley and Robert P. Multhauf is Chairman of the Department of Science and Technology in the Smithsonian Institution's Museum of History and Technology._
The intensity of gravity, or the acceleration of a freely falling body, is an important physical quantity for the several physical sciences. The intensity of gravity determines the weight of a standard pound or kilogram as a standard or unit of force. In physical experiments, the force on a body may be measured by determining the weight of a known mass which serves to establish equilibrium against it. Thus, in the absolute determination of the ampere with a current balance, the force between two coils carrying current is balanced by the earth's gravitational force upon a body of determinable mass. The intensity of gravity enters into determinations of the size of the earth from the angular velocity of the moon, its distance from the earth, and Newton's inverse square law of gravitation and the laws of motion. Prediction of the motion of an artificial satellite requires an accurate knowledge of gravity for this astronomical problem.
The gravity field of the earth also provides data for a determination of the figure of the earth, or geoid, but for this problem of geodesy relative values of gravity are sufficient. If g is the intensity of gravity at some reference station, and [Delta]g is the difference between intensities at two stations, the values of gravity in geodetic calculations enter as ratios ([Delta]g)/g over the surface of the earth. Gravimetric investigations in conjunction with other forms of geophysical investigation, such as seismology, furnish data to test hypotheses concerning the internal structure of the earth.
Whether the intensity of gravity is sought in absolute or relative measure, the most widely used instrument for its determination since the creation of classical mechanics has been the pendulum. In recent decades, there have been invented gravity meters based upon the principle of the spring, and these instruments have made possible the rapid determination of relative values of gravity to a high degree of accuracy. The gravity meter, however, must be calibrated at stations where the absolute value of gravity has been determined by other means if absolute values are sought. For absolute determinations of gravity, the pendulum historically has been the principal instrument employed. Although alternative methods of determining absolute values of gravity are now in use, the pendulum retains its value for absolute determinations, and even retains it for relative determinations, as is exemplified by the Cambridge Pendulum Apparatus and that of the Dominion Observatory at Ottawa, Ontario.
The pendulums employed for absolute or relative determinations of gravity have been of two basic types. The first form of pendulum used as a physical instrument consisted of a weight suspended by a fiber, cord, or fine wire, the upper end of which was attached to a fixed support. Such a pendulum may be called a "simple" pendulum; the enclosure of the word simple by quotation marks is to indicate that such a pendulum is an approximation to a simple, or mathematical pendulum, a conceptual object which consists of a mass-point suspended by a weightless inextensible cord. If l is the length of the simple pendulum, the time of swing (half-period in the sense of physics) for vibrations of infinitely small amplitude, as derived from Newton's laws of motion and the hypothesis that weight is proportional to mass, is T = [pi][sqrt](l/g).
The second form of pendulum is the compound, or physical, pendulum. It consists of an extended solid body which vibrates about a fixed axis under the action of the weight of the body. A compound pendulum may be constituted to oscillate about one axis only, in which case it is nonreversible and applicable only for relative measurements. Or a compound pendulum may be constituted to oscillate about two axes, in which case it is reversible (or "convertible") and may be used to determine absolute values of gravity. Capt. Henry Kater, F.R.S., during the years 1817-1818 was the first to design, construct, and use a compound pendulum for the absolute determination of gravity. He constructed a convertible pendulum with two knife edges and with it determined the absolute value of gravity at the house of Henry Browne, F.R.S., in Portland Place, London. He then constructed a similar compound pendulum with only one knife edge, and swung it to determine relative values of gravity at a number of stations in the British Isles. The 19th century witnessed the development of the theory and practice of observations with pendulums for the determination of absolute and relative values of gravity.
Galileo, Huygens, and Newton
The pendulum has been both an objective and an instrument of physical investigation since the foundations of classical mechanics were fashioned in the 17th century.[1] It is tradition that the youthful Galileo discovered that the period of oscillation of a pendulum is constant by observations of the swings of the great lamp suspended from the ceiling in the cathedral of Pisa.[2] The lamp was only a rough approximation to a simple pendulum, but Galileo later performed more accurate experiments with a "simple" pendulum which consisted of a heavy ball suspended by a cord. In an experiment designed to confirm his laws of falling bodies, Galileo lifted the ball to the level of a given altitude and released it. The ball ascended to the same level on the other side of the vertical equilibrium position and thereby confirmed a prediction from the laws. Galileo also discovered that the period of vibration of a "simple" pendulum varies as the square root of its length, a result which is expressed by the formula for the time of swing of the ideal simple pendulum. He also used a pendulum to measure lapse of time, and he designed a pendulum clock. Galileo's experimental results are important historically, but have required correction in the light of subsequent measurements of greater precision.
Mersenne in 1644 made the first determination of the length of the seconds pendulum,[3] that is, the length of a simple pendulum that beats seconds (half-period in the sense of physics). Subsequently, he proposed the problem to determine the length of the simple pendulum equivalent in period to a given compound pendulum. This problem was solved by Huygens, who in his famous work _Horologium oscillatorium_ ... (1673) set forth the theory of the compound pendulum.[4]
Huygens derived a theorem which has provided the basis for the employment of the reversible compound pendulum for the absolute determination of the intensity of gravity. The theorem is that a given compound pendulum possesses conjugate points on opposite sides of the center of gravity; about these points, the periods of oscillation are the same. For each of these points as center of suspension the other point is the center of oscillation, and the distance between them is the length of the equivalent simple pendulum. Earlier, in 1657, Huygens independently had invented and patented the pendulum clock, which rapidly came into use for the measurement of time. Huygens also created the theory of centripetal force which made it possible to calculate the effect of the rotation of the earth upon the observed value of gravity.
The theory of the gravity field of the earth was founded upon the laws of motion and the law of gravitation by Isaac Newton in his famous _Principia_ (1687). It follows from the Newtonian theory of gravitation that the acceleration of gravity as determined on the surface of the earth is the resultant of two factors: the principal factor is the gravitational attraction of the earth upon bodies, and the subsidiary factor is the effect of the rotation of the earth. A body at rest on the surface of the earth requires some of the gravitational attraction for the centripetal acceleration of the body as it is carried in a circle with constant speed by the rotation of the earth about its axis. If the rotating earth is used as a frame of reference, the effect of the rotation is expressed as a centrifugal force which acts to diminish the observed intensity of gravity.
* * * * *
GLOSSARY OF GRAVITY TERMINOLOGY
ABSOLUTE GRAVITY: the value of the acceleration of gravity, also expressed by the length of the seconds pendulum.
RELATIVE GRAVITY: the value of the acceleration of gravity relative to the value at some standard point.
SIMPLE PENDULUM: see theoretical pendulum.
THEORETICAL PENDULUM: a heavy bob (point-mass) at the end of a weightless rod.
SECONDS PENDULUM: a theoretical or simple pendulum of such length that its time of swing (half-period) is one second. (This length is about one meter.)
GRAVITY PENDULUM: a precisely made pendulum used for the measurement of gravity.
COMPOUND PENDULUM: a pendulum in which the supporting rod is not weightless; in other words, any actual pendulum.
CONVERTIBLE PENDULUM: a compound pendulum having knife edges at different distances from the center of gravity. Huygens demonstrated (1673) that if such a pendulum were to swing with equal periods from either knife edge, the distance between those knife edges would be equal to the length of a theoretical or simple pendulum of the same period.
REVERSIBLE PENDULUM: a convertible pendulum which is also symmetrical in form.
INVARIABLE PENDULUM: a compound pendulum with only one knife edge, used for relative measurement of gravity.
* * * * *
From Newton's laws of motion and the hypothesis that weight is proportional to mass, the formula for the half-period of a simple pendulum is given by T = [pi][sqrt](l/g). If a simple pendulum beats seconds, 1 = [pi][sqrt]([lambda]/g), where [lambda] is the length of the seconds pendulum. From T = [pi][sqrt](l/g) and 1 = [pi][sqrt]([lambda]/g), it follows that [lambda] = l/T^{2}. Then g = [pi]^{2}[lambda]. Thus, the intensity of gravity can be expressed in terms of the length of the seconds pendulum, as well as by the acceleration of a freely falling body. During the 19th century, gravity usually was expressed in terms of the length of the seconds pendulum, but present practice is to express gravity in terms of g, for which the unit is the gal, or one centimeter per second per second.
Figure of the Earth
A principal contribution of the pendulum as a physical instrument has been the determination of the figure of the earth.[5] That the earth is spherical in form was accepted doctrine among the ancient Greeks. Pythagoras is said to have been the first to describe the earth as a sphere, and this view was adopted by Eudoxus and Aristotle.
The Alexandrian scientist Eratosthenes made the first estimate of the diameter and circumference of a supposedly spherical earth by an astronomical-geodetic method. He measured the angle between the directions of the rays of the sun at Alexandria and Syene (Aswan), Egypt, and estimated the distance between these places from the length of time required by a caravan of camels to travel between them. From the central angle corresponding to the arc on the surface, he calculated the radius and hence the circumference of the earth. A second measurement was undertaken by Posidonius, who measured the altitudes of stars at Alexandria and Rhodes and estimated the distance between them from the time required to sail from one place to the other.
With the decline of classical antiquity, the doctrine of the spherical shape of the earth was lost, and only one investigation, that by the Arabs under Calif Al-Mamun in A.D. 827, is recorded until the 16th century. In 1525, the French mathematician Fernel measured the length of a degree of latitude between Paris and Amiens by the revolutions of the wheels of his carriage, the circumference of which he had determined. In England, Norwood in 1635 measured the length of an arc between London and York with a chain. An important forward step in geodesy was the measurement of distance by triangulation, first by Tycho Brahe, in Denmark, and later, in 1615, by Willebrord Snell, in Holland.
Of historic importance, was the use of telescopes in the triangulation for the measurement of a degree of arc by the Abbe Jean Picard in 1669.[6] He had been commissioned by the newly established Academy of Sciences to measure an arc corresponding to an angle of 1 deg., 22', 55" of the meridian between Amiens and Malvoisine, near Paris. Picard proposed to the Academy the measurement of the meridian of Paris through all of France, and this project was supported by Colbert, who obtained the approval of the King. In 1684, Giovanni-Domenico Cassini and De la Hire commenced a trigonometrical measure of an arc south of Paris; subsequently, Jacques Cassini, the son of Giovanni-Domenico, added the arc to the north of Paris. The project was completed in 1718. The length of a degree of arc south of Paris was found to be greater than the length north of Paris. From the difference, 57,097 toises[7] minus 56,960 toises, it was concluded that the polar diameter of the earth is larger than the equatorial diameter, i.e., that the earth is a prolate spheroid (fig. 3).
Meanwhile, Richer in 1672 had been sent to Cayenne, French Guiana, to make astronomical observations and to measure the length of the seconds pendulum.[8] He took with him a pendulum clock which had been adjusted to keep accurate time in Paris. At Cayenne, however, Richer found that the clock was retarded by 2 minutes and 28 seconds per day (fig. 1). He also fitted up a "simple" pendulum to vibrate in seconds and measured the length of this seconds pendulum several times every week for 10 months. Upon his return to Paris, he found that the length of the "simple" pendulum which beat seconds at Cayenne was 1-1/4 Paris lines[9] shorter than the length of the seconds pendulum at Paris. Huygens explained the reduction in the length of the seconds pendulum--and, therefore, the lesser intensity of gravity at the equator with respect to the value at Paris--in terms of his theory of centripetal force as applied to the rotation of the earth and pendulum.[10]
A more complete theory was given by Newton in the _Principia_.[11] Newton showed that if the earth is assumed to be a homogeneous, mutually gravitating fluid globe, its rotation will result in a bulging at the equator. The earth will then have the form of an oblate spheroid, and the intensity of gravity as a form of universal gravitation will vary with position on the surface of the earth. Newton took into account gravitational attraction and centrifugal action, and he calculated the ratio of the axes of the spheroid to be 230:229. He calculated and prepared a table of the lengths of a degree of latitude and of the seconds pendulum for every 5 deg. of latitude from the equator to the pole. A discrepancy between his predicted length of the seconds pendulum at the equator and Richer's measured length was explained by Newton in terms of the expansion of the scale with higher temperatures near the equator.
Newton's theory that the earth is an oblate spheroid was confirmed by the measurements of Richer, but was rejected by the Paris Academy of Sciences, for it contradicted the results of the Cassinis, father and son, whose measurements of arcs to the south and north of Paris had led to the conclusion that the earth is a prolate spheroid. Thus, a controversy arose between the English scientists and the Paris Academy. The conflict was finally resolved by the results of expeditions sent by the Academy to Peru and Sweden. The first expedition, under Bouguer, La Condamine, and Godin in 1735, went to a region in Peru, and, with the help of the Spaniard Ullo, measured a meridian arc of about 3 deg. 7' near Quito, now in Ecuador.[12] The second expedition, with Maupertuis and Clairaut in 1736, went to Lapland within the Arctic Circle and measured an arc of about 1 deg. in length.[13] The northern arc of 1 deg. was found to be longer than the Peruvian arc of 1 deg., and thus it was confirmed that the earth is an oblate spheroid, that is, flattened at the poles, as predicted by the theory of Newton.
The period from Eratosthenes to Picard has been called the spherical era of geodesy; the period from Picard to the end of the 19th century has been called the ellipsoidal period. During the latter period the earth was conceived to be an ellipsoid, and the determination of its ellipticity, that is, the difference of equatorial radius and polar radius divided by the equatorial radius, became an important geodetic problem. A significant contribution to the solution of this problem was made by determinations of gravity by the pendulum.
An epoch-making work during the ellipsoidal era of geodesy was Clairaut's treatise, _Theorie de la figure de la terre_.[14] On the hypothesis that the earth is a spheroid of equilibrium, that is, such that a layer of water would spread all over it, and that the internal density varies so that layers of equal density are coaxial spheroids, Clairaut derived a historic theorem: If [gamma]_{E}, [gamma]_{P} are the values of gravity at the equator and pole, respectively, and c the centrifugal force at the equator divided by [gamma]_{E}, then the ellipticity [alpha] = (5/2)c - ([gamma]_{P} - [gamma]_{E})/[gamma]_{E}.
Laplace showed that the surfaces of equal density might have any nearly spherical form, and Stokes showed that it is unnecessary to assume any law of density as long as the external surface is a spheroid of equilibrium.[15] It follows from Clairaut's theorem that if the earth is an oblate spheroid, its ellipticity can be determined from relative values of gravity and the absolute value at the equator involved in c. Observations with nonreversible, invariable compound pendulums have contributed to the application of Clairaut's theorem in its original and contemporary extended form for the determination of the figure and gravity field of the earth.
Early Types of Pendulums
The pendulum employed in observations of gravity prior to the 19th century usually consisted of a small weight suspended by a filament (figs. 4-6). The pioneer experimenters with "simple" pendulums changed the length of the suspension until the pendulum beat seconds. Picard in 1669 determined the length of the seconds pendulum at Paris with a "simple" pendulum which consisted of a copper ball an inch in diameter suspended by a fiber of pite from jaws (pite was a preparation of the leaf of a species of aloe and was not affected appreciably by moisture).
A celebrated set of experiments with a "simple" pendulum was conducted by Bouguer[16] in 1737 in the Andes, as part of the expedition to measure the Peruvian arc. The bob of the pendulum was a double truncated cone, and the length was measured from the jaw suspension to the center of oscillation of the thread and bob. Bouguer allowed for change of length of his measuring rod with temperature and also for the buoyancy of the air. He determined the time of swing by an elementary form of the method of coincidences. The thread of the pendulum was swung in front of a scale and Bouguer observed how long it took the pendulum to lose a number of vibrations on the seconds clock. For this purpose, he noted the time when the beat of the clock was heard and, simultaneously, the thread moved past the center of the scale. A historic aspect of Bouguer's method was that he employed an "invariable" pendulum, that is, the length was maintained the same at the various stations of observation, a procedure that has been described as having been invented by Bouguer.
Since T = [pi][sqrt](l/g), it follows that (T_{1})^{2}/(T_{2})^{2} = g_{2}/g_{1}. Thus, if the absolute value of gravity is known at one station, the value at any other station can be determined from the ratio of the squares of times of swing of an invariable pendulum at the two stations. From the above equation, if T_{1} is the time of swing at a station where the intensity of gravity is g, and T_{2} is the time at a station where the intensity is g + [Delta]g, then [Delta]g/g = (T_{1})^{2}/(T_{2})^{2} - 1.
Bouguer's investigations with his invariable pendulum yielded methods for the determination of the internal structure of the earth. On the Peruvian expedition, he determined the length of the seconds pendulum at three stations, including one at Quito, at varying distances above sea level. If values of gravity at stations of different elevation are to be compared, they must be reduced to the same level, usually to sea level. Since gravity decreases with height above sea level in accordance with the law of gravitation, a free-air reduction must be applied to values of gravity determined above the level of the sea. Bouguer originated the additional reduction for the increase in gravity on a mountain or plateau caused by the attraction of the matter in a plate. From the relative values of gravity at elevated stations in Peru and at sea level, Bouguer calculated that the mean density of the earth was 4.7 times greater than that of the _cordilleras_.[17] For greater accuracy in the study of the internal structure of the earth, in the 19th century the Bouguer plate reduction came to be supplemented by corrections for irregularities of terrain and by different types of isostatic reduction.
La Condamine, who like Bouguer was a member of the Peruvian expedition, conducted his own pendulum experiments (fig. 4). He experimented in 1735 at Santo Domingo en route to South America,[18] then at various stations in South America, and again at Paris upon his return to France. His pendulum consisted of a copper ball suspended by a thread of pite. For experimentation the length initially was about 12 feet, and the time of swing 2 seconds, but then the length was reduced to about 3 feet with time of swing 1 second. Earlier, when it was believed that gravity was constant over the earth, Picard and others had proposed that the length of the seconds pendulum be chosen as the standard. La Condamine in 1747 revived the proposal in the form that the length of the seconds pendulum at the equator be adopted as the standard of length. Subsequently, he investigated the expansion of a toise of iron from the variation in the period of his pendulum. In 1755, he observed the pendulum at Rome with Boscovich. La Condamine's pendulum was used by other observers and finally was lost at sea on an expedition around the world. The knowledge of the pendulum acquired by the end of the 18th century was summarized in 1785 in a memoir by Boscovich.[19]
The practice with the "simple" pendulum on the part of Picard, Bouguer, La Condamine and others in France culminated in the work of Borda and Cassini in 1792 at the observatory in Paris[20] (fig. 6). The experiments were undertaken to determine whether or not the length of the seconds pendulum should be adopted as the standard of length by the new government of France. The bob consisted of a platinum ball 16-1/6 Paris lines in diameter, and 9,911 grains (slightly more than 17 ounces) in weight. The bob was held to a brass cup covering about one-fifth of its surface by the interposition of a small quantity of grease. The cup with ball was hung by a fine iron wire about 12 Paris feet long. The upper end of the wire was attached to a cylinder which was part of a wedge-shaped knife edge, on the upper surface of which was a stem on which a small adjustable weight was held by a screw thread. The knife edge rested on a steel plate. The weight on the knife-edge apparatus was adjusted so that the apparatus would vibrate with the same period as the pendulum. Thus, the mass of the suspending apparatus could be neglected in the theory of motion of the pendulum about the knife edge.
In the earlier suspension from jaws there was uncertainty as to the point about which the pendulum oscillated. Borda and Cassini hung their pendulum in front of a seconds clock and determined the time of swing by the method of coincidences. The times on the clock were observed when the clock gained or lost one complete vibration (two swings) on the pendulum. Suppose that the wire pendulum makes n swings while the clock makes 2n + 2. If the clock beats seconds exactly, the time of one complete vibration is 2 seconds, and the time of swing of the wire pendulum is T = (2n + 2)/n = 2(1 + 1/n). An error in the time caused by uncertainty in determining the coincidence of clock and wire pendulum is reduced by employing a long interval of observation 2n. The whole apparatus was enclosed in a box, in order to exclude disturbances from currents of air. Corrections were made for buoyancy, for amplitude of swing and for variations in length of the wire with temperature. The final result was that the length of the seconds pendulum at the observatory in Paris was determined to be 440.5593 Paris lines, or 993.53 mm., reduced to sea level 993.85 mm. Some years later the methods of Borda were used by other French investigators, among whom was Biot who used the platinum ball of Borda suspended by a copper wire 60 cm. long.
Another historic "simple" pendulum was the one swung by Bessel (fig. 7) for the determination of gravity at Koenigsberg 1825-1827.[21] The pendulum consisted of a ball of brass, copper, or ivory that was suspended by a fine wire, the upper end of which was wrapped and unwrapped on a horizontal cylinder as support. The pendulum was swung first from one point and then from another, exactly a "toise de Peru"[22] higher up, the bob being at the same level in each case (fig. 7). Bessel found the period of vibration of the pendulum by the method of coincidences; and in order to avoid disturbances from the comparison clock, it was placed at some distance from the pendulum under observation.
Bessel's experiments were significant in view of the care with which he determined the corrections. He corrected for the stiffness of the wire and for the lack of rigidity of connection between the bob and wire. The necessity for the latter correction had been pointed out by Laplace, who showed that through the circumstance that the pull of the wire is now on one side and now on the other side of the center of gravity, the bob acquires angular momentum about its center of gravity, which cannot be accounted for if the line of the wire, and therefore the force that it exerts, always passed through the center. In addition to a correction for buoyancy of the air considered by his predecessors, Bessel also took account of the inertia of the air set in motion by the pendulum.
The latter effect had been discovered by Du Buat in 1786,[23] but his work was unknown to Bessel. The length of the seconds pendulum at Koenigsberg, reduced to sea level, was found by Bessel to be 440.8179 lines. In 1835, Bessel determined the intensity of gravity at a site in Berlin where observations later were conducted in the Imperial Office of Weights and Measures by Charles S. Peirce of the U.S. Coast Survey.
Kater's Convertible and Invariable Pendulums
The systematic survey of the gravity field of the earth was given a great impetus by the contributions of Capt. Henry Kater, F.R.S. In 1817, he designed, constructed, and applied a convertible compound pendulum for the absolute determination of gravity at the house of Henry Browne, F.R.S., in Portland Place, London.[24] Kater's convertible pendulum (fig. 11) consisted of a brass rod to which were attached a flat circular bob of brass and two adjustable weights, the smaller of which was adjusted by a screw. The convertibility of the pendulum was constituted by the provision of two knife edges turned inwards on opposite sides of the center of gravity. The pendulum was swung on each knife edge, and the adjustable weights were moved until the times of swing were the same about each knife edge. When the times were judged to be the same, the distance between the knife edges was inferred to be the length of the equivalent simple pendulum, in accordance with Huygens' theorem on conjugate points of a compound pendulum. Kater determined the time of swing by the method of coincidences (fig. 12). He corrected for the buoyancy of the air. The final value of the length of the seconds pendulum at Browne's house in London, reduced to sea level, was determined to be 39.13929 inches.
The convertible compound pendulum had been conceived prior to its realization by Kater. In 1792, on the occasion of the proposal in Paris to establish the standard of length as the length of the seconds pendulum, Baron de Prony had proposed the employment of a compound pendulum with three axes of oscillation.[25] In 1800, he proposed the convertible compound pendulum with knife edges about which the pendulum could complete swings in equal times. De Prony's proposals were not accepted and his papers remained unpublished until 1889, at which time they were discovered by Defforges. The French decision was to experiment with the ball pendulum, and the determination of the length of the seconds pendulum was carried out by Borda and Cassini by methods previously described. Bohnenberger in his _Astronomie_ (1811),[26] made the proposal to employ a convertible pendulum for the absolute determination of gravity; thus, he has received credit for priority in publication. Capt. Kater independently conceived of the convertible pendulum and was the first to design, construct, and swing one.
After his observations with the convertible pendulum, Capt. Kater designed an invariable compound pendulum with a single knife edge but otherwise similar in external form to the convertible pendulum[27] (fig. 13). Thirteen of these Kater invariable pendulums have been reported as constructed and swung at stations throughout the world.[28] Kater himself swung an invariable pendulum at a station in London and at various other stations in the British Isles. Capt. Edward Sabine, between 1820 and 1825, made voyages and swung Kater invariable pendulums at stations from the West Indies to Greenland and Spitzbergen.[29] In 1820, Kater swung a Kater invariable pendulum at London and then sent it to Goldingham, who swung it in 1821 at Madras, India.[30] Also in 1820, Kater supplied an invariable pendulum to Hall, who swung it at London and then made observations near the equator and in the Southern Hemisphere, and at London again in 1823.[31] The same pendulum, after its knives were reground, was delivered to Adm. Luetke of Russia, who observed gravity with it on a trip around the world between 1826 and 1829.[32]
While the British were engaged in swinging the Kater invariable pendulums to determine relative values of the length of the seconds pendulum, or of gravity, the French also sent out expeditions. Capt. de Freycinet made initial observations at Paris with three invariable brass pendulums and one wooden one, and then carried out observations at Rio de Janeiro, Cape of Good Hope, Ile de France, Rawak (near New Guinea), Guam, Maui, and various other places.[33] A similar expedition was conducted in 1822-1825 by Captain Duperry.[34]
During the years from 1827 to 1840, various types of pendulum were constructed and swung by Francis Baily, a member of the Royal Astronomical Society, who reported in 1832 on experiments in which no less than 41 different pendulums were swung in vacuo, and their characteristics determined.[35] In 1836, Baily undertook to advise the American Lt. Charles Wilkes, who was to head the United States Exploring Expedition of 1838-1842, on the procurement of pendulums for this voyage. Wilkes ordered from the London instrument maker, Thomas Jones, two unusual pendulums, which Wilkes described as "those considered the best form by Mr. Baily for traveling pendulums," and which Baily, himself, described as "precisely the same as the two invariable pendulums belonging to this [Royal Astronomical] Society," except for the location of the knife edges.
The unusual feature of these pendulums was in their symmetry of mass as well as of form. They were made of bars, of iron in one case, and of brass in the other, and each had two knife edges at opposite ends equidistant from the center. Thus, although they resembled reversible pendulums, their symmetry of mass prevented their use as such, and they were rather equivalent to four separate invariable pendulums.[36]
Wilkes was taught the use of the pendulum by Baily, and conducted experiments at Baily's house, where the latter had carried out the work reported on in 1832. The subsequent experiments made on the U.S. Exploring Expedition were under the charge of Wilkes, himself, who made observations on 11 separate occasions, beginning with that in London (1836) and followed by others in New York, Washington, D.C., Rio de Janeiro, Sydney, Honolulu, "Pendulum Peak" (Mauna Loa), Mount Kanoha, Nesqually (Oregon Territory), and, finally, two more times in Washington, D.C. (1841 and 1845).
Wilkes' results were communicated to Baily, who appears to have found the work defective because of insufficient attention to the maintenance of temperature constancy and to certain alterations made to the pendulums.[37] The results were also to have been included in the publications of the Expedition, but were part of the unpublished 24th volume. Fortunately they still exist, in what appears to be a printer's proof.[38]
The Kater invariable pendulums were used to investigate the internal constitution of the earth. Airy sought to determine the density of the earth by observing the times of swing of pendulums at the top and bottom of a mine. The first experiments were made in 1826 at the Dolcoath copper mine in Cornwall, and failed when the pendulum fell to the bottom. In 1854, the experiments were again undertaken in the Harton coalpit, near Sunderland.[39] Gravity at the surface was greater than below, because of the attraction of a shell equal to the depth of the pit. From the density of the shell as determined from specimens of rock, Airy found the density of the earth to be 6-1/2 times greater than that of water. T. C. Mendenhall, in 1880, used a Kater convertible pendulum in an invariable manner to compare values of gravity on Fujiyama and at Tokyo, Japan.[40] He used a "simple" pendulum of the Borda type to determine the absolute value of gravity at Tokyo. From the values of gravity on the mountain and at Tokyo, and an estimate of the volume of the mountain, he estimated the mean density of the earth as 5.77 times greater than that of water.
In 1879, Maj. J. Herschel, R.E., stated:
The years from 1840 to 1865 are a complete blank, if we except Airy's relative density experiments in 1854. This pause was broken simultaneously in three different ways. Two pendulums of the Kater pattern were sent to India; two after Bessel's design were set to work in Russia; and at Geneva, Plantamour's zealous experiments with a pendulum of the same kind mark the commencement of an era of renewed activity on the European continent.[41]
With the statement that Kater invariable pendulums nos. 4 and 6 (1821) were used in India between 1865 and 1873, we now consider the other events mentioned by Herschel.
Repsold-Bessel Reversible Pendulum
As we have noted, Bessel made determinations of gravity with a ball ("simple") pendulum in the period 1825-1827 and in 1835 at Koenigsberg and Berlin, respectively. In the memoir on his observations at Koenigsberg, he set forth the theory of the symmetrical compound pendulum with interchangeable knife edges.[42] Bessel demonstrated theoretically that if the pendulum were symmetrical with respect to its geometrical center, if the times of swing about each axis were the same, the effects of buoyancy and of air set in motion would be eliminated. Laplace had already shown that the knife edge must be regarded as a cylinder and not as a mere line of support. Bessel then showed that if the knife edges were equal cylinders, their effects were eliminated by inverting the pendulum; and if the knife edges were not equal cylinders, the difference in their effects was canceled by interchanging the knives and again determining the times of swing in the so-called erect and inverted positions. Bessel further showed that it is unnecessary to make the times of swing exactly equal for the two knife edges.
The simplified discussion for infinitely small oscillations in a vacuum is as follows: If T_{1} and T_{2} are the times of swing about the knife edges, and if h_{1} and h_{2} are distances of the knife edges from the center of gravity, and if k is the radius of gyration about an axis through the center of gravity, then from the equation of motion of a rigid body oscillating about a fixed axis under gravity
(T_{1})^{2} = [pi]^{2}(k^{2} + (h_{1})^{2})/gh_{1},
(T_{2})^{2} = [pi]^{2}(k^{2} + (h_{2})^{2})/gh_{2}.
Then
(h_{1}(T_{1})^{2} - h_{2}(T_{2})^{2})/(h_{1} - h_{2})
= ([pi]^{2}/g)(h_{1} + h_{2})
= [tau]^{2}.
[tau] is then the time of swing of a simple pendulum of length h_{1} + h_{2}. If the difference T_{1} - T_{2} is sufficiently small,
[tau] = (h_{1}T_{1} - h_{2}T_{2})/(h_{1} - h_{2}).
Prior to its publication by Bessel in 1828, the formula for the time of swing of a simple pendulum of length h_{1} + h_{2} in terms of T_{1}, T_{2} had been given by C. F. Gauss in a letter to H. C. Schumacher dated November 28, 1824.[43]
The symmetrical compound pendulum with interchangeable knives, for which Bessel gave a posthumously published design and specifications,[44] has been called a reversible pendulum; it may thereby be distinguished from Kater's unsymmetrical convertible pendulum. In 1861, the Swiss Geodetic Commission was formed, and in one of its first sessions in 1862 it was decided to add determinations of gravity to the operations connected with the measurement--at different points in Switzerland--of the arc of the meridian traversing central Europe.[45] It was decided further to employ a reversible pendulum of Bessel's design and to have it constructed by the firm of A. Repsold and Sons, Hamburg. It was also decided to make the first observations with the pendulum in Geneva; accordingly, the Repsold-Bessel pendulum (fig. 16) was sent to Prof. E. Plantamour, director of the observatory at Geneva, in the autumn of 1864.[46]
The Swiss reversible pendulum was about 560 mm. in length (distance between the knife edges) and the time of swing was approximately 3/4 second. At the extremities of the stem of the pendulum were movable cylindrical disks, one of which was solid and heavy, the other hollow and light. It was intended by the mechanicians that equality of times of oscillation about the knife edges would be achieved by adjusting the position of a movable disk. The pendulum was hung by a knife edge on a plate supported by a tripod and having an attachment from which a measuring rod could be suspended so that the distance between the knife edges could be measured by a comparator. Plantamour found it impracticable to adjust a disk until the times of swing about each knife edge were equal. His colleague, Charles Cellerier,[47] then showed that if (T_{1} - T_{2})/T_{1} is sufficiently small so that one can neglect its square, one can determine the length of the seconds pendulum from the times of swing about the knife edges by a theory which uses the distances of the center of gravity from the respective knife edges. Thus, a role for the position of the center of gravity in the theory of the reversible pendulum, which had been set forth earlier by Bessel, was discovered independently by Cellerier for the Swiss observers of pendulums.
In 1866, Plantamour published an extensive memoir "Experiences faites a Geneve avec le pendule a reversion." Another memoir, published in 1872, presented further results of determinations of gravity in Switzerland. Plantamour was the first scientist in western Europe to use a Repsold-Bessel reversible pendulum and to work out methods for its employment.
The Russian Imperial Academy of Sciences acquired two Repsold-Bessel pendulums, and observations with them were begun in 1864 by Prof. Sawitsch, University of St. Petersburg, and others.[48] In 1869, the Russian pendulums were loaned to the India Survey in order to enable members of the Survey to supplement observations with the Kater invariable pendulums nos. 4 and 6 (1821). During the transport of the Russian apparatus to India, the knives became rusted and the apparatus had to be reconditioned. Capt. Heaviside of the India Survey observed with both pendulums at Kew Observatory, near London, in the spring of 1874, after which the Russian pendulums were sent to Pulkowa (Russia) and were used for observations there and in the Caucasus.
The introduction of the Repsold-Bessel reversible pendulum for the determination of gravity was accompanied by the creation of the first international scientific association, one for geodesy. In 1861, Lt. Gen. J. J. Baeyer, director of the Prussian Geodetic Survey, sent a memorandum to the Prussian minister of war in which he proposed that the independent geodetic surveys of the states of central Europe be coordinated by the creation of an international organization.[49] In 1862, invitations were sent to the various German states and to other states of central Europe. The first General Conference of the association, initially called _Die Mittel-Europaeische Gradmessung_, also _L'Association Geodesique Internationale_, was held from the 15th to the 22d of October 1864 in Berlin.[50] The Conference decided upon questions of organization: a general conference was to be held ordinarily every three years; a permanent commission initially consisting of seven members was to be the scientific organ of the association and to meet annually; a central bureau was to be established for the reception, publication, and distribution of reports from the member states.
Under the topic "Astronomical Questions," the General Conference of 1864 resolved that there should be determinations of the intensity of gravity at the greatest possible number of points of the geodetic network, and recommended the reversible pendulum as the instrument of observation.[51] At the second General Conference, in Berlin in 1867, on the basis of favorable reports by Dr. Hirsch, director of the observatory at Neuchatel, of Swiss practice with the Repsold-Bessel reversible pendulum, this instrument was specifically recommended for determinations of gravity.[52] The title of the association was changed to _Die Europaeische Gradmessung_; in 1886, it became _Die Internationale Erdmessung_, under which title it continued until World War I.
On April 1, 1866, the Central Bureau of _Die Europaeische Gradmessung_ was opened in Berlin under the presidency of Baeyer, and in 1868 there was founded at Berlin, also under his presidency, the Royal Prussian Geodetic Institute, which obtained regular budgetary status on January 1, 1870. A reversible pendulum for the Institute was ordered from A. Repsold and Sons, and it was delivered in the spring of 1869. The Prussian instrument was symmetrical geometrically, as specified by Bessel, but different in form from the Swiss and Russian pendulums. The distance between the knife edges was 1 meter, and the time of swing approximately 1 second. The Prussian Repsold-Bessel pendulum was swung at Leipzig and other stations in central Europe during the years 1869-1870 by Dr. Albrecht under the direction of Dr. Bruhns, director of the observatory at Leipzig and chief of the astronomical section of the Geodetic Institute. The results of these first observations appeared in a publication of the Royal Prussian Geodetic Institute in 1871.[53]
Results of observations with the Russian Repsold-Bessel pendulums were published by the Imperial Academy of Sciences. In 1872, Prof. Sawitsch reported the work for western Europeans in "Les variations de la pesanteur dans les provinces occidentales de l'Empire russe."[48] In November 1873, the Austrian Geodetic Commission received a Repsold-Bessel reversible pendulum and on September 24, 1874, Prof. Theodor von Oppolzer reported on observations at Vienna and other stations to the Fourth General Conference of _Die Europaeische Gradmessung_ in Dresden.[54] At the fourth session of the Conference, on September 28, 1874, a Special Commission, consisting of Baeyer, as chairman, and Bruhns, Hirsch, von Oppolzer, Peters, and Albrecht, was appointed to consider (under Topic 3 of the program): "Observations for the determination of the intensity of gravity," the question, "Which Pendulum-apparatuses are preferable for the determination of many points?"
After the adoption of the Repsold-Bessel reversible pendulum for gravity determinations in Europe, work in the field was begun by the U.S. Coast Survey under the superintendency of Prof. Benjamin Peirce. There is mention in reports of observations with pendulums prior to Peirce's direction to his son Charles on November 30, 1872, "to take charge of the Pendulum Experiments of the Coast Survey and to direct and inspect all parties engaged in such experiments and as often as circumstances will permit, to take the field with a party...."[55] Systematic and important gravity work by the Survey was begun by Charles Sanders Peirce. Upon receiving notice of his appointment, the latter promptly ordered from the Repsolds a pendulum similar to the Prussian instrument. Since the firm of mechanicians was engaged in making instruments for observations of the transit of Venus in 1874, the pendulum for the Coast Survey could not be constructed immediately. Meanwhile, during the years 1873-1874, Charles Peirce conducted a party which made observations of gravity in the Hoosac Tunnel near North Adams, and at Northampton and Cambridge, Massachusetts. The pendulums used were nonreversible, invariable pendulums with conical bobs. Among them was a silver pendulum, but similar pendulums of brass were used also.[56]
In 1874, Charles Peirce expressed the desire to be sent to Europe for at least a year, beginning about March 1, 1875, "to learn the use of the new convertible pendulum and to compare it with those of the European measure of a Degree and the Swiss and to compare" his "invariable pendulums in the manner which has been used by swinging them in London and Paris."[57]
Charles S. Peirce, assistant, U.S. Coast Survey, sailed for Europe on April 3, 1875, on his mission to obtain the Repsold-Bessel reversible pendulum ordered for the Survey and to learn the methods of using it for the determination of gravity. In England, he conferred with Maxwell, Stokes, and Airy concerning the theory and practice of research with pendulums. In May, he continued on to Hamburg and obtained delivery from the Repsolds of the pendulum for the Coast Survey (fig. 17). Peirce then went to Berlin and conferred with Gen. Baeyer, who expressed doubts of the stability of the Repsold stand for the pendulum. Peirce next went to Geneva, where, under arrangements with Prof. Plantamour, he swung the newly acquired pendulum at the observatory.[58]
In view of Baeyer's expressed doubts of the rigidity of the Repsold stand, Peirce performed experiments to measure the flexure of the stand caused by the oscillations of the pendulum. His method was to set up a micrometer in front of the pendulum stand and, with a microscope, to measure the displacement caused by a weight passing over a pulley, the friction of which had been determined. Peirce calculated the correction to be applied to the length of the seconds pendulum--on account of the swaying of the stand during the swings of the pendulum--to amount to over 0.2 mm. Although Peirce's measurements of flexure in Geneva were not as precise as his later measurements, he believed that failure to correct for flexure of the stand in determinations previously made with Repsold pendulums was responsible for appreciable errors in reported values of the length of the seconds pendulum.
The Permanent Commission of _Die Europaeische Gradmessung_ met in Paris, September 20-29, 1875. In conjunction with this meeting, there was held on September 21 a meeting of the Special Commission on the Pendulum. The basis of the discussion by the Special Commission was provided by reports which had been submitted in response to a circular sent out by the Central Bureau to the members on February 26, 1874.[59]
Gen. Baeyer stated that the distance of 1 meter between the knife edges of the Prussian Repsold-Bessel pendulum made it unwieldy and unsuited for transport. He declared that the instability of the stand also was a source of error. Accordingly, Gen. Baeyer expressed the opinion that absolute determinations of gravity should be made at a control station by a reversible pendulum hung on a permanent, and therefore stable stand, and he said that relative values of gravity with respect to the control station should be obtained in the field by means of a Bouguer invariable pendulum. Dr. Bruhns and Dr. Peters agreed with Gen. Baeyer; however, the Swiss investigators, Prof. Plantamour and Dr. Hirsch reported in defense of the reversible pendulum as a field instrument, as did Prof. von Oppolzer of Vienna. The circumstance that an invariable pendulum is subject to changes in length was offered as an argument in favor of the reversible pendulum as a field instrument.
Peirce was present during these discussions by the members of the Special Commission, and he reported that his experiments at Geneva demonstrated that the oscillations of the pendulum called forth a flexure of the support which hitherto had been neglected. The observers who used the Swiss and Austrian Repsold pendulums contended, in opposition to Peirce, that the Repsold stand was stable.
The outcome of these discussions was that the Special Commission reported to the Permanent Commission that the Repsold-Bessel reversible pendulum, except for some small changes, satisfied all requirements for the determination of gravity. The Special Commission proposed that the Repsold pendulums of the several states be swung at the Prussian Eichungsamt in Berlin where, as Peirce pointed out, Bessel had made his determination of the intensity of gravity with a ball pendulum in 1835. Peirce was encouraged to swing the Coast Survey reversible pendulum at the stations in France, England, and Germany where Borda and Cassini, Kater, and Bessel, respectively, had made historic determinations. The Permanent Commission, in whose sessions Peirce also participated, by resolutions adopted the report of the Special Commission on the Pendulum.[60]
During the months of January and February 1876, Peirce conducted observations in the Grande Salle du Meridien at the observatory in Paris where Borda, Biot, and Capt. Edward Sabine had swung pendulums early in the 19th century. He conducted observations in Berlin from April to June 1876 and, by experiment, determined the correction for flexure to be applied to the value of gravity previously obtained with the Prussian instrument. Subsequent observations were made at Kew. After his return to the United States on August 26, 1876, Peirce conducted experiments at the Stevens Institute in Hoboken, New Jersey, where he made careful measurements of the flexure of the stand by statical and dynamical methods. In Geneva, he had secured the construction of a vacuum chamber in which the pendulum could be swung on a support which he called the Geneva support. At the Stevens Institute, Peirce swung the Repsold-Bessel pendulum on the Geneva support and determined the effect of different pressures and temperatures on the period of oscillation of the pendulum. These experiments continued into 1878.[61]
Meanwhile, the Permanent Commission met October 5-10, 1876, in Brussels and continued the discussion of the pendulum.[62] Gen. Baeyer reported on Peirce's experiments in Berlin to determine the flexure of the stand. The difference of 0.18 mm. in the lengths of the seconds pendulum as determined by Bessel and as determined by the Repsold instrument agreed with Peirce's estimate of error caused by neglect of flexure of the Repsold stand. Dr. Hirsch, speaking for the Swiss survey, and Prof. von Oppolzer, speaking for the Austrian survey, contended, however, that their stands possessed sufficient stability and that the results found by Peirce applied only to the stands and bases investigated by him. The Permanent Commission proposed further study of the pendulum.
The Fifth General Conference of _Die Europaeische Gradmessung_ was held from September 27 to October 2, 1877, in Stuttgart.[63] Peirce had instructions from Supt. Patterson of the U.S. Coast Survey to attend this conference, and on arrival presented a letter of introduction from Patterson requesting that he, Peirce, be permitted to participate in the sessions. Upon invitation from Prof. Plantamour, as approved by Gen. Ibanez, president of the Permanent Commission, Peirce had sent on July 13, 1877, from New York, the manuscript of a memoir titled "De l'Influence de la flexibilite du trepied sur l'oscillation du pendule a reversion." This memoir and others by Cellerier and Plantamour confirming Peirce's work were published as appendices to the proceedings of the conference. As appendices to Peirce's contribution were published also two notes by Prof. von Oppolzer. At the second session on September 29, 1877, when Plantamour reported that the work of Hirsch and himself had confirmed experimentally the independent theoretical work of Cellerier and the theoretical and experimental work of Peirce on flexure, Peirce described his Hoboken experiments.
During the discussions at Stuttgart on the flexure of the Repsold stand, Herve Faye, president of the Bureau of Longitudes, Paris, suggested that the swaying of the stand during oscillations of the pendulum could be overcome by the suspension from one support of two similar pendulums which oscillated with equal amplitudes and in opposite phases. This proposal was criticized by Dr. Hirsch, who declared that exact observation of passages of a "double pendulum" would be difficult and that two pendulums swinging so close together would interfere with each other. The proposal of the double pendulum came up again at the meeting of the Permanent Commission at Geneva in 1879.[64] On February 17, 1879, Peirce had completed a paper "On a Method of Swinging Pendulums for the Determination of Gravity, Proposed by M. Faye." In this paper, Peirce presented the results of an analytical mechanical investigation of Faye's proposal. Peirce set up the differential equations, found the solutions, interpreted them physically, and arrived at the conclusion "that the suggestion of M. Faye ... is as sound as it is brilliant and offers some peculiar advantages over the existing method of swinging pendulums."
In a report to Supt. Patterson, dated July 1879, Peirce stated: "I think it is important before making a new pendulum apparatus to experiment with Faye's proposed method."[65] He wrote further: "The method proves to be perfectly sound in theory, and as it would greatly facilitate the work it is probably destined eventually to prevail. We must unfortunately leave to other surveys the merit of practically testing and introducing the new method, as our appropriations are insufficient for us to maintain the leading position in this matter, which we otherwise might take." Copies of the published version of Peirce's remarks were sent to Europe. At a meeting of the Academy of Sciences in Paris on September 1, 1879, Faye presented a report on Peirce's findings.[66] The Permanent Commission met September 16-20, 1879, in Geneva. At the third session on September 19, by action of Gen. Baeyer, copies of Peirce's paper on Faye's proposed method of swinging pendulums were distributed. Dr. Hirsch again commented adversely on the proposal, but moved that the question be investigated and reported on at the coming General Conference. The Permanent Commission accepted the proposal of Dr. Hirsch, and Prof. Plantamour was named to report on the matter at the General Conference. At Plantamour's request, Charles Cellerier was appointed to join him, since the problem essentially was a theoretical one.
The Sixth General Conference of _Die Europaeische Gradmessung_ met September 13-16, 1880, in Munich.[67] Topic III, part 7 of the program was entitled "On Determinations of Gravity through pendulum observations. Which construction of a pendulum apparatus corresponds completely to all requirements of science? Special report on the pendulum."
The conference received a memoir by Cellerier[68] on the theory of the double pendulum and a report by Plantamour and Cellerier.[69] Cellerier's mathematical analysis began with the equations of Peirce and used the latter's notation as far as possible. His general discussion included the results of Peirce, but he stated that the difficulties to be overcome did not justify the employment of the "double pendulum." He presented an alternative method of correcting for flexure based upon a theory by which the flexure caused by the oscillation of a given reversible pendulum could be determined from the behavior of an auxiliary pendulum of the same length but of different weight. This method of correcting for flexure was recommended to the General Conference by Plantamour and Cellerier in their joint report. At the fourth session of the conference on September 16, 1880, the problem of the pendulum was discussed and, in consequence, a commission consisting of Faye, Helmholtz, Plantamour (replaced in 1882 by Hirsch), and von Oppolzer was appointed to study apparatus suitable for relative determinations of gravity.
The Permanent Commission met September 11-15, 1882, at The Hague,[70] and at its last session appointed Prof. von Oppolzer to report to the Seventh General Conference on different forms of apparatus for the determination of gravity. The Seventh Conference met October 15-24, 1883, in Rome,[71] and, at its eighth session, on October 22, received a comprehensive, critical review from Prof. von Oppolzer entitled "Ueber die Bestimmung der Schwere mit Hilfe verschiedener Apparate."[72] Von Oppolzer especially expounded the advantages of the Bessel reversible pendulum, which compensated for air effects by symmetry of form if the times of swing for both positions were maintained between the same amplitudes, and compensated for irregular knife edges by making them interchangeable. Prof. von Oppolzer reviewed the problem of flexure of the Repsold stand and stated that a solution in the right direction was the proposal--made by Faye and theoretically pursued by Peirce--to swing two pendulums from the same stand with equal amplitudes and in opposite phases, but that the proposal was not practicable. He concluded that for absolute determinations of gravity, the Bessel reversible pendulum was highly appropriate if one swung two exemplars of different weight from the same stand for the elimination of flexure. Prof. von Oppolzer's important report recognized that absolute determinations were less accurate than relative ones, and should be conducted only at special places.
The discussions initiated by Peirce's demonstration of the flexure of the Repsold stand resulted, finally, in the abandonment of the plan to make absolute determinations of gravity at all stations with the reversible pendulum.
Peirce and Defforges Invariable, Reversible Pendulums
The Repsold-Bessel reversible pendulum was designed and initially used to make absolute determinations of gravity not only at initial stations such as Kew, the observatory in Paris, and the Smithsonian Institution in Washington, D.C., but also at stations in the field. An invariable pendulum with a single knife edge, however, is adequate for relative determinations. As we have seen, such invariable pendulums had been used by Bouguer and Kater, and after the experiences with the Repsold apparatus had been recommended again by Baeyer for relative determinations. But an invariable pendulum is subject to uncontrollable changes of length. Peirce proposed to detect such changes in an invariable pendulum in the field by combining the invariable and reversible principles. He explained his proposal to Faye in a letter dated July 23, 1880, and he presented it on September 16, 1880, at the fourth session of the sixth General Conference of _Die Europaeische Gradmessung_, in Munich.[73]
As recorded in the Proceedings of the Conference, Peirce wrote:
But I obviate it in making my pendulum both invariable and reversible. Every alteration of the pendulum will be revealed immediately by the change in the difference of the two periods of oscillation in the two positions. Once discovered, it will be taken account of by means of new measures of the distance between the two supports.
Peirce added that it seemed to him that if the reversible pendulum perhaps is not the best instrument to determine absolute gravity, it is, on condition that it be truly invariable, the best to determine relative gravity. Peirce further stated that he would wish that the pendulum be formed of a tube of drawn brass with heavy plugs of brass equally drawn. The cylinder would be terminated by two hemispheres; the knives would be attached to tongues fixed near the ends of the cylinder.
During the years 1881 and 1882, four invariable, reversible pendulums were made after the design of Peirce at the office of the U.S. Coast and Geodetic Survey in Washington, D.C. The report of the superintendent for the year 1880-1881 states:
A new pattern of the reversible pendulum has been invented, having its surface as nearly as convenient in the form of an elongated ellipsoid. Three of these instruments have been constructed, two having a distance of one meter between the knife edges and the third a distance of one yard. It is proposed to swing one of the meter pendulums at a temperature near 32 deg. F. at the same time that the yard is swung at 60 deg. F., in order to determine anew the relation between the yard and the meter.[74]
The report for 1881-1882 mentions four of these Peirce pendulums.
A description of the Peirce invariable, reversible pendulums was given by Assistant E. D. Preston in "Determinations of Gravity and the Magnetic Elements in Connection with the United States Scientific Expedition to the West Coast of Africa, 1889-90."[75] The invariable, reversible pendulum, Peirce no. 4, now preserved in the Smithsonian Institution's Museum of History and Technology (fig. 34), may be taken as typical of the meter pendulums: In the same memoir, Preston gives the diameter of the tube as 63.7 mm., thickness of tube 1.5 mm., weight 10.680 kilograms, and distance between the knives 1.000 meter.
The combination of invariability and reversibility in the Peirce pendulums was an innovation for relative determinations. Indeed, the combination was criticized by Maj. J. Herschel, R.E., of the Indian Survey, at a conference on gravity held in Washington in May 1882 on the occasion of his visit to the United States for the purpose of connecting English and American stations by relative determinations with three Kater invariable pendulums. These three pendulums have been designated as nos. 4, 6 (1821), and 11.[76]
Another novel characteristic of the Peirce pendulums was the mainly cylindrical form. Prof. George Gabriel Stokes, in a paper "On the Effect of the Internal Friction of Fluids on the Motion of Pendulums"[77] that was read to the Cambridge Philosophical Society on December 9, 1850, had solved the hydrodynamical equations to obtain the resistance to the motions of a sphere and a cylinder in a viscous fluid. Peirce had studied the effect of viscous resistance on the motion of his Repsold-Bessel pendulum, which was symmetrical in form but not cylindrical. The mainly cylindrical form of his pendulums (fig. 19) permitted Peirce to predict from Stokes' theory the effect of viscosity and to compare the results with experiment. His report of November 20, 1889, in which he presented the comparison of experimental results with the theory of Stokes, was not published.[78]
Peirce used his pendulums in 1883 to establish a station at the Smithsonian Institution that was to serve as the base station for the Coast and Geodetic Survey for some years. Pendulum Peirce no. 1 was swung at Washington in 1881 and was then taken by the party of Lieutenant Greely, U.S.A., on an expedition to Lady Franklin Bay where it was swung in 1882 at Fort Conger, Grinnell Land, Canada. Peirce nos. 2 and 3 were swung by Peirce in 1882 at Washington, D.C.; Hoboken, New Jersey; Montreal, Canada; and Albany, New York. Assistant Preston took Peirce no. 3 on a U.S. eclipse expedition to the Caroline Islands in 1883. Peirce in 1885 swung pendulums nos. 2 and 3 at Ann Arbor, Michigan; Madison, Wisconsin; and Ithaca, New York. Assistant Preston in 1887 swung Peirce nos. 3 and 4 at stations in the Hawaiian Islands, and in 1890 he swung Peirce nos. 3 and 4 at stations on the west coast of Africa.[79]
The new pattern of pendulum designed by Peirce was also adopted in France, after some years of experience with a Repsold-Bessel pendulum. Peirce in 1875 had swung his Repsold-Bessel pendulum at the observatory in Paris, where Borda and Cassini, and Biot, had made historic observations and where Sabine also had determined gravity by comparison with Kater's value at London. During the spring of 1880, Peirce made studies of the supports for the pendulums of these earlier determinations and calculated corrections to those results for hydrodynamic effects, viscosity, and flexure. On June 14, 1880, Peirce addressed the Academy of Sciences, Paris, on the value of gravity at Paris, and compared his results with the corrected results of Borda and Biot and with the transferred value of Kater.[80]
In the same year the French Geographic Service of the Army acquired a Repsold-Bessel reversible pendulum of the smaller type, and Defforges conducted experiments with it.[81] He introduced the method of measuring flexure from the movement of interference fringes during motion of the pendulum. He found an appreciable difference between dynamical and statical coefficients of flexure and concluded that the "correction formula of Peirce and Cellerier is suited perfectly to practice and represents exactly the variation of period caused by swaying of the support, on the condition that one uses the statical coefficient." Defforges developed a theory for the employment of two similar pendulums of the same weight, but of different length, and hung by the same knives. This theory eliminated the flexure of the support and the curvature of the knives from the reduction of observations.
Pendulums of 1-meter and of 1/2-meter distance between the knife edges were constructed from Defforges' design by Brunner Brothers in Paris (fig. 21). These Defforges pendulums were cylindrical in form with hemispherical ends like the Peirce pendulums, and were hung on knives that projected from the sides of the pendulum, as in some unfinished Gautier pendulums designed by Peirce in 1883 in Paris.
Von Sterneck and Mendenhall Pendulums
While scientists who had used the Repsold-Bessel pendulum apparatus discussed its defects and limitations for gravity surveys, Maj. Robert von Sterneck of Austria-Hungary began to develop an excellent apparatus for the rapid determination of relative values of gravity.[82] Maj. von Sterneck's apparatus contained a nonreversible pendulum 1/4-meter in length, and 1/2-second time of swing. The pendulum was hung by a single knife edge, which rested on a plate that was supported by a tripod. The pendulum was swung in a chamber from which air was exhausted and which could be maintained at any desired temperature. Times of swing were determined by the observation of coincidences of the pendulum with chronometer signals. In the final form a small mirror was attached to the knife edge perpendicular to the plane of vibration of the pendulum and a second fixed mirror was placed close to it so that the two mirrors were parallel when the pendulum was at rest. The chronometer signals worked a relay that gave a horizontal spark which was reflected into the telescope from the mirrors. When the pendulum was at rest, the image of the spark in both mirrors appeared on the horizontal cross wire in the telescope, and during oscillation of the pendulum the two images appeared in that position upon coincidence. In view of the reduced size of the pendulum, the chamber in which it was swung was readily portable, and with an improved method of observing coincidences, relative determinations of gravity could be made with rapidity and accuracy.
By 1887 Maj. von Sterneck had perfected his apparatus, and it was widely adopted in Europe for relative determinations of gravity. He used his apparatus in extensive gravity surveys and also applied it in the silver mines in Saxony and Bohemia, by the previously described methods of Airy, for investigations into the internal constitution of the earth.
On July 1, 1889, Thomas Corwin Mendenhall became superintendent of the U.S. Coast and Geodetic Survey. Earlier, he had been professor of physics at the University of Tokyo and had directed observations of pendulums for the determination of gravity on Fujiyama and at Tokyo. Supt. Mendenhall, with the cooperation of members of his staff in Washington, designed a new pendulum apparatus of the Von Sterneck type, and in October 1890 he ordered construction of the first model.[83]
Like the Von Sterneck apparatus, the Mendenhall pendulum apparatus employed a nonreversible, invariable pendulum 1/4-meter in length and of slightly more than 1/2-second in time of swing. Initially, the knife edge was placed in the head of the pendulum and hung on a fixed plane support, but after some experimentation Mendenhall attached the plane surface to the pendulum and hung it on a fixed knife edge. An apparatus was provided with a set of three pendulums, so that if discrepancies appeared in the results, the pendulum at fault could be detected. There was also a dummy pendulum which carried a thermometer. A pendulum was swung in a receiver in which the pressure and temperature of the air were controlled. The time of swing was measured by coincidences with the beat of a chronometer. The coincidences were determined by an optical method with the aid of a flash apparatus.
The flash apparatus was contained in a light metal box which supported an observing telescope and which was mounted on a stand. Within the box was an electromagnet whose coils were connected with a chronometer circuit and whose armature carried a long arm that moved two shutters, in both of which were horizontal slits of the same size. The shutters were behind the front face of the box, which also had a horizontal slit. A flash of light from an oil lamp or an electric spark was emitted from the box when the circuit was broken, but not when it was closed. When the circuit was broken a spring caused the arm to rise, and the shutters were actuated so that the three slits came into line and a flash of light was emitted. A small circular mirror was set in each side of the pendulum head, so that from either face of the pendulum the image of the illuminated slit could be reflected into the field of the observing telescope. A similar mirror was placed parallel to these two mirrors and rigidly attached to the support. The chronometer signals broke the circuit, causing the three slits momentarily to be in line, and when the images of the slit in the two mirrors coincided, a coincidence was observed. A coincidence occurred whenever the pendulum gained or lost one oscillation on the beat of the chronometer. The relative intensity of gravity was determined by observations with the first Mendenhall apparatus at Washington, D.C., at stations on the Pacific Coast and in Alaska, and at the Stevens Institute, Hoboken, New Jersey, between March and October 1891.
Under Supt. Mendenhall's direction a smaller, 1/4-second, pendulum apparatus was also constructed and tested, but did not offer advantages over the 1/2-second apparatus, which therefore continued in use.
In accordance with Peirce's theory of the flexure of the stand under oscillations of the pendulum, determinations of the displacement of the receiver of the Mendenhall apparatus were part of a relative determination of gravity by members of the Coast and Geodetic Survey. Initially, a statical method was used, but during 1908-1909 members of the Survey adapted the Michelson interferometer for the determinations of flexure during oscillations from the shift of fringes.[84] The first Mendenhall pendulums were made of bronze, but about 1920 invar was chosen because of its small coefficient of expansion. About 1930, Lt. E. J. Brown of the Coast and Geodetic Survey made significant improvements in the Mendenhall apparatus, and the new form came to be known as the Brown Pendulum Apparatus.[85]
The original Von Sterneck apparatus and that of Mendenhall provided for the oscillation of one pendulum at a time. After the adoption of the Von Sterneck pendulum in Europe, there were developed stands on which two or four pendulums hung at the same time. This procedure provided a convenient way to observe more than one invariable pendulum at a station for the purpose of detecting changes in length. Prof. M. Haid of Karlsruhe in 1896 described a four-pendulum apparatus,[86] and Dr. Schumann of Potsdam subsequently described a two-pendulum apparatus.[87]
The multiple-pendulum apparatus then provided a method of determining the flexure of the stand from the action of one pendulum upon a second pendulum hung on the same stand. This method of determining the correction for flexure was a development from a "Wippverfahren" invented at the Geodetic Institute in Potsdam. A dynamometer was used to impart periodic impulses to the stand, and the effect was observed upon a pendulum initially at rest. Refinements of this method led to the development of a method used by Lorenzoni in 1885-1886 to determine the flexure of the stand by action of an auxiliary pendulum upon the principal pendulum. Dr. Schumann, in 1899, gave a mathematical theory of such determinations,[88] and in his paper cited the mathematical methods of Peirce and Cellerier for the theory of Faye's proposal at Stuttgart in 1877 to swing two similar pendulums on the same support with equal amplitudes and in opposite phases.
In 1902, Dr. P. Furtwaengler[89] presented the mathematical theory of coupled pendulums in a paper in which he referred to Faye's proposal of 1877 and reported that the difficulties predicted upon its application had been found not to occur. Finally, during the gravity survey of Holland in the years 1913-1921, in view of instability of supports caused by the mobility of the soil, F. A. Vening Meinesz adopted Faye's proposed method of swinging two pendulums on the same support.[90] The observations were made with the ordinary Stueckrath apparatus, in which four Von Sterneck pendulums swung two by two in planes perpendicular to each other. This successful application of the method--which had been proposed by Faye and had been demonstrated theoretically to be sound by Peirce, who also published a design for its application--was rapidly followed for pendulum apparatus for relative determinations by Potsdam,[91] Cambridge (England),[92] Gulf Oil and Development Company,[93] and the Dominion Observatory at Ottawa.[94] Heiskanen and Vening Meinesz state:
The best way to eliminate the effect of flexure is to use two synchronized pendulums of the same length swinging on the same apparatus in the same plane and with the same amplitudes but in opposite phases; it is clear then the flexure is zero.[95]
In view of the fact that the symmetrical reversible pendulum is named for Bessel, who created the theory and a design for its application by Repsold, it appears appropriate to call the method of eliminating flexure by swinging two pendulums on the same support the Faye-Peirce method. Its successful application was made possible by Maj. von Sterneck's invention of the short, 1/4-meter pendulum.
Absolute Value of Gravity at Potsdam
The development of the reversible pendulum in the 19th century culminated in the absolute determination of the intensity of gravity at Potsdam by Kuehnen and Furtwaengler of the Royal Prussian Geodetic Institute, which then became the world base for gravity surveys.[96]
We have previously seen that in 1869 the Geodetic Institute--founded by Lt. Gen. Baeyer--had acquired a Repsold-Bessel reversible pendulum which was swung by Dr. Albrecht under the direction of Dr. Bruhns. Dissatisfaction with this instrument was expressed by Baeyer in 1875 to Charles S. Peirce, who then, by experiment and mathematical analysis of the flexure of the stand under oscillations of the pendulum, determined that previously reported results with the Repsold apparatus required correction. Dr. F. R. Helmert, who in 1887 succeeded Baeyer as director of the Institute, secured construction of a building for the Institute in Potsdam, and under his direction the scientific study of the intensity of gravity was pursued with vigor. In 1894, it was discovered in Potsdam that a pendulum constructed of very flexible material yielded results which differed markedly from those obtained with pendulums of greater stiffness. Dr. Kuehnen of the Institute discovered that the departure from expectations was the result of the flexure of the pendulum staff itself during oscillations.[97]
Peirce, in 1883, had discovered that the recesses cut in his pendulums for the insertion of tongues that carried the knives had resulted in the flexure of the pendulum staff.[98] By experiment, he also found an even greater flexure for the Repsold pendulum. In order to eliminate this source of error, Peirce designed a pendulum with knives that extended from each side of the cylindrical staff, and he received authorization from the superintendent of the Coast and Geodetic Survey to arrange for the construction of such pendulums by Gautier in Paris. Peirce, who had made his plans in consultation with Gautier, was called home before the pendulums were completed, and these new instruments remained undelivered.
In a memoir titled "Effect of the flexure of a pendulum upon its period of oscillation,"[99] Peirce determined analytically the effect on the period of a pendulum with a single elastic connection between two rigid parts of the staff. Thus, Peirce discovered experimentally the flexure of the staff and derived for a simplified case the effect on the period. It is not known if he ever found the integrated effect of the continuum of elastic connections in the pendulum. Lorenzoni, in 1896, offered a solution to the problem, and Almansi, in 1899, gave an extended analysis. After the independent discovery of the problem at the Geodetic Institute, Dr. Helmert took up the problem and criticized the theories of Peirce and Lorenzoni. He then presented his own theory of flexure in a comprehensive memoir.[100] In view of the previous neglect of the flexure of the pendulum staff in the reduction of observations, Helmert directed that the Geodetic Institute make a new absolute determination of the intensity of gravity at Potsdam. For this purpose, Kuehnen and Furtwaengler used the following reversible pendulums which had been constructed by the firm of A. Repsold and Sons in Hamburg:
1. The seconds pendulum of the Geodetic Institute procured in 1869.
2. A seconds pendulum from the Astronomical Observatory, Padua.
3. A heavy, seconds pendulum from the Imperial and Royal Military-Geographical Institute, Vienna.
4. A light, seconds pendulum from the Imperial and Royal Military-Geographical Institute.
5. A 1/2-second, reversible pendulum of the Geodetic Institute procured in 1892.
Work was begun in 1898, and in 1906 Kuehnen and Furtwaengler published their monumental memoir, "Bestimmung der Absoluten Groesze der Schwerkraft zu Potsdam mit Reversionspendeln."
The acceleration of gravity in the pendulum room of the Geodetic Institute was determined to be 981.274 +- 0.003 cm/sec^{2}. In view of the exceptionally careful and thorough determination at the Institute, Potsdam was accepted as the world base for the absolute value of the intensity of gravity. The absolute value of gravity at some other station on the Potsdam system was determined from the times of swing of an invariable pendulum at the station and at Potsdam by the relation (T_{1})^{2}/(T_{2})^{2} = g_{2}/g_{1}. Thus, in 1900, Assistant G. R. Putnam of the Coast and Geodetic Survey swung Mendenhall pendulums at the Washington base and at Potsdam, and by transfer from Potsdam determined the intensity of gravity at the Washington base to be 980.112 cm/sec^{2}.[101] In 1933, Lt. E. J. Brown made comparative measurements with improved apparatus and raised the value at the Washington base to 980.118 cm/sec^{2}.[102]
In view of discrepancies between the results of various relative determinations, the Coast and Geodetic Survey in 1928 requested the National Bureau of Standards to make an absolute determination for Washington. Heyl and Cook used reversible pendulums made of fused silica having a period of approximately 1 second. Their result, published in 1936, was interpreted to indicate that the value at Potsdam was too high by 20 parts in 1 million.[103] This estimate was lowered slightly by Sir Harold Jeffreys of Cambridge, England, who recomputed the results of Heyl and Cook by different methods.[104]
In 1939, J. S. Clark published the results of a determination of gravity with pendulums of a non-ferrous Y-alloy[105] at the National Physical Laboratory at Teddington, England, and, after recomputation of results by Jeffreys, the value was found to be 12.8 parts in 1 million less than the value obtained by transfer from Potsdam. Dr. Hugh L. Dryden of the National Bureau of Standards, and Dr. A. Berroth of the Geodetic Institute at Potsdam, have recomputed the Potsdam data by different methods of adjustment and concluded that the Potsdam value was too high by about 12 parts in a million.[106] Determination of gravity at Leningrad by Russian scientists likewise has indicated that the 1906 Potsdam value is too high. In the light of present information, it appears justifiable to reduce the Potsdam value of 981.274 by .013 cm/sec^{2} for purposes of comparison. If the Brown transfer from Potsdam in 1933 was taken as accurate, the value for the Washington base would be 980.105 cm/sec^{2}. In this connection, it is of interest to note that the value given by Charles S. Peirce for the comparable Smithsonian base in Washington, as determined by him from comparative methods in the 1880's and reported in the _Annual Report of the Superintendent of the Coast and Geodetic Survey for the year 1890-1891_, was 980.1017 cm/sec^{2}.[107] This value would appear to indicate that Peirce's pendulums, observations, and methods of reduction of data were not inferior to those of the scientists of the Royal Prussian Geodetic Institute at Potsdam.
Doubts concerning the accuracy of the Potsdam value of gravity have stimulated many new determinations of the intensity of gravity since the end of World War II. In a paper published in June 1957, A. H. Cook, Metrology Division, National Physical Laboratory, Teddington, England, stated:
At present about a dozen new absolute determinations are in progress or are being planned. Heyl and Cook's reversible pendulum apparatus is in use in Buenos Aires and further reversible pendulum experiments have been made in the All Union Scientific Research Institute of Metrology, Leningrad (V N I I M) and are planned at Potsdam. A method using a very long pendulum was tried out in Russia about 1910 and again more recently and there are plans for similar work in Finland. The first experiment with a freely falling body was that carried out by Volet who photographed a graduated scale falling in an enclosure at low air pressure. Similar experiments have been completed in Leningrad and are in progress at the Physikalisch-Technische Bundesanstalt (Brunswick) and at the National Research Council (Ottawa), and analogous experiments are being prepared at the National Physical Laboratory and at the National Bureau of Standards. Finally, Professor Medi, Director of the Istituto Nazionale di Geofisica (Rome), is attempting to measure the focal length of the paraboloidal surface of a liquid in a rotating dish.[108]
Application of Gravity Surveys
We have noted previously that in the ancient and early modern periods, the earth was presupposed to be spherical in form. Determination of the figure of the earth consisted in the measurement of the radius by the astronomical-geodetic method invented by Eratosthenes. Since the earth was assumed to be spherical, gravity was inferred to be constant over the surface of the earth. This conclusion appeared to be confirmed by the determination of the length of the seconds pendulum at various stations in Europe by Picard and others. The observations of Richer in South America, the theoretical discussions of Newton and Huygens, and the measurements of degrees of latitude in Peru and Sweden demonstrated that the earth is an oblate spheroid.
The theory of gravitation and the theory of central forces led to the result that the intensity of gravity is variable over the surface of the earth. Accordingly, determinations of the intensity of gravity became of value to the geodesist as a means of determining the figure of the earth. Newton, on the basis of the meager data available to him, calculated the ellipticity of the earth to be 1/230 (the ellipticity is defined by (a-b)/a, where a is the equatorial radius and b the polar radius). Observations of the intensity of gravity were made on the historic missions to Peru and Sweden. Bouguer and La Condamine found that at the equator at sea level the seconds pendulum was 1.26 Paris-lines shorter than at Paris. Maupertuis found that in northern Sweden a certain pendulum clock gained 59.1 seconds per day on its rate in Paris. Then Clairaut, from the assumption that the earth is a spheroid of equilibrium, derived a theorem from which the ellipticity of the earth can be derived from values of the intensity of gravity.
Early in the 19th century a systematic series of observations began to be conducted in order to determine the intensity of gravity at stations all over the world. Kater invariable pendulums, of which 13 examples have been mentioned in the literature, were used in surveys of gravity by Kater, Sabine, Goldingham, and other British pendulum swingers. As has been noted previously, a Kater invariable pendulum was used by Adm. Luetke of Russia on a trip around the world. The French also sent out expeditions to determine values of gravity. After several decades of relative inactivity, Capts. Basevi and Heaviside of the Indian Survey carried out an important series of observations from 1865 to 1873 with Kater invariable pendulums and the Russian Repsold-Bessel pendulums. In 1881-1882 Maj. J. Herschel swung Kater invariable pendulums nos. 4, 6 (1821), and 11 at stations in England and then brought them to the United States in order to make observations which would connect American and English base stations.[109]
The extensive sets of observations of gravity provided the basis of calculations of the ellipticity of the earth. Col. A. R. Clarke in his _Geodesy_ (London, 1880) calculated the ellipticity from the results of gravity surveys to be 1/(292.2 +- 1.5). Of interest is the calculation by Charles S. Peirce, who used only determinations made with Kater invariable pendulums and corrected for elevation, atmospheric effect, and expansion of the pendulum through temperature.[110] He calculated the ellipticity of the earth to be 1/(291.5 +- 0.9).
The 19th century witnessed the culmination of the ellipsoidal era of geodesy, but the rapid accumulation of data made possible a better approximation to the figure of the earth by the geoid. The geoid is defined as the average level of the sea, which is thought of as extended through the continents. The basis of geodetic calculations, however, is an ellipsoid of reference for which a gravity formula expresses the value of normal gravity at a point on the ellipsoid as a function of gravity at sea level at the equator, and of latitude. The general assembly of the International Union of Geodesy and Geophysics, which was founded after World War I to continue the work of _Die Internationale Erdmessung_, adopted in 1924 an international reference ellipsoid,[111] of which the ellipticity, or flattening, is Hayford's value 1/297. In 1930, the general assembly adopted a correlated International Gravity Formula of the form
[gamma] = [gamma]_{E}(1 + [beta]sin^{2} [phi] + [epsilon]sin^{2} 2[phi])
where [gamma] is normal gravity at latitude [phi], [gamma]_{E} is the value of gravity at sea level at the equator, [beta] is a parameter which is computed on the basis of Clairaut's theorem from the flattening value of the meridian, and [epsilon] is a constant which is derived theoretically. The plumb line is perpendicular to the geoid, and the components of angle between the perpendiculars to geoid and reference ellipsoid are deflections of the vertical. The geoid is above the ellipsoid of reference under mountains and it is below the ellipsoid on the oceans, where the geoid coincides with mean sea level. In physical geodesy, gravimetric data are used for the determination of the geoid and components of deflections of the vertical. For this purpose, one must reduce observed values of gravity to sea level by various reductions, such as free-air, Bouguer, isostatic reductions. If g_{0} is observed gravity reduced to sea level and [gamma] is normal gravity obtained from the International Gravity Formula, then
[Delta]g = g_{0} - [gamma]
is the gravity anomaly.[112]
In 1849, Stokes derived a theorem whereby the distance N of the geoid from the ellipsoid of reference can be obtained from an integration of gravity anomalies over the surface of the earth. Vening Meinesz further derived formulae for the calculation of components of the deflection of the vertical.
Geometrical geodesy, which was based on astronomical-geodetic methods, could give information only concerning the external form of the figure of the earth. The gravimetric methods of physical geodesy, in conjunction with methods such as those of seismology, enable scientists to test hypotheses concerning the internal structure of the earth. Heiskanen and Vening Meinesz summarize the present-day achievements of the gravimetric method of physical geodesy by stating[113] that it alone can give:
1. The flattening of the reference ellipsoid.
2. The undulations N of the geoid.
3. The components of the deflection of the vertical [xi] and [eta] at any point, oceans and islands included.
4. The conversion of existing geodetic systems to the same world geodetic system.
5. The reduction of triangulation base lines from the geoid to the reference ellipsoid.
6. The correction of errors in triangulation in mountainous regions due to the effect of the deflections of the vertical.
7. Geophysical applications of gravity measurements, e.g., the isostatic study of the earth's interior and the exploration of oil fields and ore deposits.
With astronomical observations or with existing triangulations, the gravimetric method can accomplish further results. Heiskanen and Vening Meinesz state:
It is the firm conviction of the authors that the gravimetric method is by far the best of the existing methods for solving the main problems of geodesy, i.e., to determine the shape of the geoid on the continents as well as at sea and to convert the existing geodetic systems to the world geodetic system. It can also give invaluable help in the computation of the reference ellipsoid.[114]
Summary
Since the creation of classical mechanics in the 17th century, the pendulum has been a basic instrument for the determination of the intensity of gravity, which is expressed as the acceleration of a freely falling body. Basis of theory is the simple pendulum, whose time of swing under gravity is proportional to the square root of the length divided by the acceleration due to gravity. Since the length of a simple pendulum divided by the square of its time of swing is equal to the length of a pendulum that beats seconds, the intensity of gravity also has been expressed in terms of the length of the seconds pendulum. The reversible compound pendulum has served for the absolute determination of gravity by means of a theory developed by Huygens. Invariable compound pendulums with single axes also have been used to determine relative values of gravity by comparative times of swing.
The history of gravity pendulums begins with the ball or "simple" pendulum of Galileo as an approximation to the ideal simple pendulum. Determinations of the length of the seconds pendulum by French scientists culminated in a historic determination at Paris by Borda and Cassini, from the corrected observations with a long ball pendulum. In the 19th century, Bessel found the length of the seconds pendulum at Koenigsberg and Berlin by observations with a ball pendulum and by original theoretical considerations. During the century, however, the compound pendulum came to be preferred for absolute and relative determinations.
Capt. Henry Kater, at London, constructed the first convertible compound for an absolute determination of gravity, and then he designed an invariable compound pendulum, examples of which were used for relative determinations at various stations in Europe and elsewhere. Bessel demonstrated theoretically the advantages of a reversible compound pendulum which is symmetrical in form and is hung by interchangeable knives. The firm of A. Repsold and Sons in Hamburg constructed pendulums from the specifications of Bessel for European gravity surveys.
Charles S. Peirce in 1875 received delivery in Hamburg of a Repsold-Bessel pendulum for the U.S. Coast Survey and observed with it in Geneva, Paris, Berlin, and London. Upon an initial stimulation from Baeyer, founder of _Die Europaeische Gradmessung_, Peirce demonstrated by experiment and theory that results previously obtained with the Repsold apparatus required correction, because of the flexure of the stand under oscillations of the pendulum. At the Stuttgart conference of the geodetic association in 1877, Herve Faye proposed to solve the problem of flexure by swinging two similar pendulums from the same support with equal amplitudes and in opposite phases. Peirce, in 1879, demonstrated theoretically the soundness of the method and presented a design for its application, but the "double pendulum" was rejected at that time. Peirce also designed and had constructed four examples of a new type of invariable, reversible pendulum of cylindrical form which made possible the experimental study of Stokes' theory of the resistance to motion of a pendulum in a viscous fluid. Commandant Defforges, of France, also designed and used cylindrical reversible pendulums, but of different length so that the effect of flexure was eliminated in the reduction of observations. Maj. Robert von Sterneck, of Austria-Hungary, initiated a new era in gravity research by the invention of an apparatus with a short pendulum for relative determinations of gravity. Stands were then constructed in Europe on which two or four pendulums were hung at the same time. Finally, early in the present century, Vening Meinesz found that the Faye-Peirce method of swinging pendulums hung on a Stueckrath four-pendulum stand solved the problem of instability due to the mobility of the soil in Holland.
The 20th century has witnessed increasing activity in the determination of absolute and relative values of gravity. Gravimeters have been perfected and have been widely used for rapid relative determinations, but the compound pendulums remain as indispensable instruments. Mendenhall's replacement of knives by planes attached to nonreversible pendulums has been used also for reversible ones. The Geodetic Institute at Potsdam is presently applying the Faye-Peirce method to the reversible pendulum.[115] Pendulums have been constructed of new materials, such as invar, fused silica, and fused quartz. Minimum pendulums for precise relative determinations have been constructed and used. Reversible pendulums have been made with "I" cross sections for better stiffness. With all these modifications, however, the foundations of the present designs of compound pendulum apparatus were created in the 19th century.
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FOOTNOTES
[1] The basic historical documents have been collected, with a bibliography of works and memoirs published from 1629 to the end of 1885, in _Collection de memoires relatifs a la physique, publies par la Societe francaise de Physique_ [hereinafter referred to as _Collection de memoires_]: vol. 4, _Memoires sur le pendule, precedes d'une bibliographie_ (Paris: Gauthier-Villars, 1889); and vol. 5, _Memoires sur le pendule_,