letter I or M, which would have disturbed the formation of the

chronogram desired. Literally, "sit planetis" means "May he be eternal ruler _by_ [or _through_] favor of the planets," while "sit planetarum" is to be translated "May he be eternal ruler _of_ the planets." Father Winters considered both versions somewhat overexaggerated and proposed that the best translation might be "Long Live Francis I, Emperor."

[15] The word "Tempe" refers to the Vale of Tempe, in Thessaly, through which the Peneus River flows. It is between Mounts Olympus and Ossa, and is situated between the town of Larissa and the sea. In mythology, it is told that these mounts were originally joined and Hercules separated them to allow the river to pass between them. The word "Tempe" is also used to mean any pleasant place. Thus, the inscription "Tempe indesinenter clausa, Scaturigo signata" is literally translated "Tempe always closed, A fount of water sealed up" or, freely translated, as "A garden enclosed, a fountain sealed up."

[16] "Phoebi" or Phoebus, called Apollo, the sun god; Phoebes or Diana, the moon goddess, sister of Apollo.

[17] PIPPA, op. cit. (footnote 11), pp. 23-25.

[18] PERINI, _Statistica del Trentino, Biblioteca Communale del Trentino_, vol. 2, p. 57 (cons. 6, carta 9); TOVAZZI, _Biblioteca Tirolese_, pp. 406-407.

[19] PIPPA, op. cit. (footnote 11), pp. 24-25.

[20] PIAMONTE, _La Nauna Descritta al Viaggiattore_.

[21] ESPOSTI, "La Sala 'Innocente Binda' al Museo della Scienza e della Tecnica di Milano," pp. 18-21.

Appendix

SYNOPSIS OF THE COMPLETE MECHANICAL WORKS OF THE FIRST CLOCK

[Translated from the section entitled "Synopsis Totius Operis Mechanici" in Francesco Borghesi's first book _Novissima Ac Perpetua Astronomica Ephemeris Authomatica Theorico-Practica..._.]

I

Of three movable indices, the farthest from the center of the dial is fitted with an index on either side and marked with four segments of a circle. Immediately below are five numbers, divided into the days of setting the measure of the mean-synodic age of the moon, and into signs, degrees of the signs, and of the distance of the moon from the sun. These, in each revolution, revolve once around the solar disk superimposed on the mean synodic-lunar disk, and also around the lunar disk. The upper indices, meanwhile, in the two external greatest orbits, measure the time continuously, in the accustomed manner of the Germans--the middle index measuring by hours and the uppermost by the first minutes [of hours].

II

Inside these three circles, perpendicular above their center, is a small index of the seconds of minutes. At each first minute of time, being the fastest of all, it describes the smallest orbit. Next to this are two other slightly larger circles divided into 30 degrees, one [rotating?] from the right, the other from the left. These two indices are arranged in such a fashion that the one rotating from the observer's left completes its period 12 times during one, mean, solar-astronomical year. The one [rotating] from the right likewise completes its cycle 12 times during the period of one mean-synodic moon. In between these, there is placed another small sphere, divided into 40 arbitrary parts, whose dial does not move automatically, but is moved by hand for speeding up or slowing down the course of the time, or of the perpendicular.

III

Diagonally from the sides of the center of the three larger indices, six other indices revolve: three on the left from one center, and three on the right from another. The uppermost of the three which are on the right of the observer [and which are] decorated with a small disk of the sun, runs its cycle once during a mean solar-astronomical year. The second measures the distance of the sun from its apogee. The third revolves 12 times, with each lunar revolution from one node to the same [repeated] node. Under the point of the uppermost index, first lie the months of the year which are inscribed, and the days of each month, but having only 28 days assigned to February; then the signs of the zodiac, and their several degrees. The circle corresponding to the middle index, extending through the first semicircle from apogee to the lower perigee and returning through the second semicircle to the upper locations of apogee, shows the true equation or eccentricity of the sun, joined with the little equation of the moon in syzygy. [These equations are] measured by geometric-astronomic proportion for each distance of the sun from its apogee or perigee in degrees, and in sufficiently small parts of degrees, with the title added above in their proper places, whether an addition is to be made to the mean location of the sun or a subtraction from the same, so that the true longitude of the sun may be calculated. Three circles are assigned to the lowest index, of which 30 degrees of distance of the moon from its nodes comprise the larger. The middle circle is based on the hypothesis of the mean invariable diameters (that is, of the sun, the moon, and the terrestrial shadow), and is divided into hours and quarters of duration. The last circle is divided by the trigonometric laws into the inches of magnitude of lunar eclipses. Lying between these circles, there is another eccentric circle (black with a spot) exhibiting the shadow of the earth, in which the little moon sinks itself, carried by the lowest index. In any ecliptic full moons, the patent number of inches of immersion somehow affects the minds of the cultured, but also the scheme of maximum obscuration affects the eyes of the illiterate themselves.

IV

Of the three indices which revolve from the left, the uppermost completes its cycle within 12 hours, just as the hour index. The middle one with two pointers on diametrically opposite sides, carries the marks of conjunction and opposition of the luminous bodies, with a movement equal to the course of the sun from lunar apogee or perigee. The lowest index, fitted with a single pointer, indicates the motion of the moon from its apogee or perigee. Under these three indices, there is situated a common circle, divided into 12 parts, each of which are further divided into 30 parts through its outer circumference. I have said a common circle, for, with respect to the first index, the division represents 12 hours, and the double subdivision representing the double set of minutes of the hours serves for an excitator for anytime at all, at will. For as often as the little index reaches the twelfth hour, first being moved by hand wherever you prefer, a little hammer strikes the little bell many times. But if you observe the second or the third index, the first division provides the signs, and the subdivision of the signs gives the individual degrees of the distance of the sun from the lunar apogee, or of the moon from its apogee, respectively. To this is added two other interior circles from the same center: to the larger is inserted the equation of the center of the moon in its conjunctions and oppositions; and on the smaller the equation of the same moon in its quarters, astronomically-geometrically proportioned to the distance of the moon from its apogee or perigee. In the first case, the equation is to be subtracted from the mean longitude of the moon, descending from apogee to perigee; in the second case, to be added to the mean longitude of the moon ascending from perigee to apogee; and, in the third semicircle of the index, as the rubric directs, common to both equations, added around the center.

V

Perpendicularly under the center of the machine, two other indices are carried about one and the same center. The one nearer to the observer--bearing in one of two points diametrically opposite the small disk of the sun, in the other the disk of the moon--runs a course equal to the motion of the sun from the head or the tail of the dragon (_Draco_). The other, of simple construction, marked with a small moon, signifies in like manner the motion of the moon from the head or the tail of the dragon.

Immediately below, there is a larger circle, common [referring] to both these indices, which is divided into 12 parts. Each of these parts in turn, in the outer periphery, is subdivided further into 30 parts, which are the 12 signs of the zodiac and the individual degrees of the signs of distance of the sun and the moon from the head of the dragon.

In the second circle is read the latitude of the moon, measured by degrees, etc., on a trigonometric scale, by signs and degrees of distance of the moon from its nodes, that is, from the head or tail of the dragon. When the second index is descending from the head of the dragon to the tail, the latitude will be to the north of the solar path; that is, the ecliptic. On the other hand, it will be south of the ecliptic when the same index is returning upward from the tail to the head of the dragon as advised by the title inscribed on the third circle.

Finally, on the fourth and last circle are seen more prime minutes of the circle for reducing the orbit of the moon to the ecliptic. That the true longitude of the moon may be obtained more accurately, these must be subtracted from the longitude of the moon already calculated in the first and third quadrant of the circle of the second index. On the other hand, they are to be added to the same in the second and fourth quadrant, as is noted in their respective places, according to the theory of right ascensions.

Here, then, [you have] as finally completed, delineation of the great index which was partially described before in this book.

From two points of that index which perpendicularly correspond to the center of these circles, a pair of compasses, by an unvaried aperture up to the circumference of the first larger circle, has marked off four segments of a circle. The two larger segments, equal among themselves, in one aperture refer to the sun, and the two smaller in the other, likewise equal, refer to the moon. The one pointer is for determining the solar eclipses; the other, for lunar. Both segments of each division, like little wings of the index, stretch to the extent of the degree of distance of the moon from its nodes, and to which that determined latitude corresponds. On one side, that latitude precisely equals the radii of the earth, the sun, and the moon, as the termini of solar eclipses; and, on the other side, precisely equals the radii of the earth's shadow and of the moon, as the confines of lunar eclipses. The apexes of the last index, diametrically limited [opposite], indicate the age of the moon, and its mean distance from the sun; one pointer, upon which the sun sits, measuring the mean days and degrees from the full moon; the other, on which the moon sits, measuring the mean days and degrees from the new moon.

VI

Besides the larger and smaller indices already mentioned, all [of which] revolve within the periphery of the three largest circles, six dials in this clock also revolve within the same circles which are to be seen through six openings of the frontispiece. The first of these, intended to indicate the phases of the moon by an unusual method (completely black, and decorated with the characters of the principal aspects of the moon) continually revolves interiorly around the center of the machine and at the new moon, it completely removes from sight the face of the moon through the round window. It continually recedes through the first half of the circle until, at the time of the full moon, it restores the moon, looking out with a full star. Soon again, too slow to be observed, it returns through the other half of the circle, so that in the next conjunction, the whole face of the moon may have a covering of darkness, once again to be removed.

The other dials are moved by spontaneous advances at stated times. The first of these shows, through a square opening, the day of the month; the second, through another opening, shows the current day of the week with the characters of the seven planets which, according to ancient superstition, preside over each day of the week (now, by a truer form of religion divided by the Church into ferias, etc.); that is, the sun, the moon, Mars, Mercury, Jupiter, Venus and Saturn, to which I have added the numbers of the ferias. These two little dials are advanced daily, by a sudden movement at midnight. The remaining three are changed automatically only once a year on the first of January.

The first of these dials contains five little cells, opening from a common window: in the first cell, at the edge of the dial, is found the dominical letter; in the second, the cycle of the sun; in the third, the character; in the fourth, the sign; and, in the fifth, the house of the planet dominating the year. The second dial shows the epacts, with the golden number. The third, and last of all, shows the Roman cycle.

Finally, as indicated by the epact and the dominical letter in an immovable table added outside, are the feastdays and other movable events of the year; that is, Easter, the four seasons, the Rogation Days, etc.

VII

But lest the various movements of the indices and the various beginnings of the divisions tend to cause some fatigue, the precaution has been taken, that all the indices by common law are moved from the top towards the right of the observer, and from thence all the arithmetic divisions of the circles take their beginning. And lest the multitude of different figures should deceive the eye, the larger divisions of the circles have been marked by Roman numbers, that is, by capital letters of the alphabet; others, in other places, by differently colored numbers. Thus, the movements of the indices, the distribution of the circles and the multitude of numbers not only do not disturb the eyes and the mind, but rather marvelously delight them.

VIII

After having completed briefly the description of the dial and the indices and their motions, I have not without reason delayed in satisfying the desires of many who wish to learn at least the method by which, from this mechanism, may be calculated the true times of new and full moons, and their ecliptics. In order to make these matters clearer, it is necessary that they be explained here at greater length.

With the indices, then, adjusted astronomically-geographically to the longitude of any given region, and to the mean time whether past, present or future, and assuming the clock to be in normal operation (as at present it has been for a whole year and more), then the moon will be in conjunction with the sun in the heavens. When the equations on the mechanism are examined, the sun and moon shall be found to be in the same degree of longitude, and in the same part of a degree. There will also be an ecliptic new moon that is in conjunction with a solar eclipse, or rather with a terrestrial eclipse. This will occur if, at that time, both apexes of the first index, located below the center of the clock, are hidden by the two segments of the circle extending from the center of the mechanism through the lowest index.

And the eclipse will be greater and greater and, consequently, visible in more regions of the earth, the more deeply the two pointers, indicating the distance of the sun from its apogee, are hidden in the center of the segments.

But whether the eclipse takes place in the head or in the tail of the dragon, or whether it is north or south, is indicated by the small disk of the sun attached to one of the two pointers hidden by the segments of the circle. If, at that time, the little disk shall be found in the head of the dragon inscribed on the plane of the dial, then the sun has been snatched from the earth and ingloriously entombed, as it were, in the huge jaw of the dragon. Then, ... the heavens themselves will lend aid to the woeful pomp of the senseless funeral in full darkness by suddenly lighting the unhappy lamps of the fixed stars. However, if the little disk occupies the tail of the dragon on the mechanism, then the sun in the heavens also, as if freed from the toils of the immense dragon's tail, will emerge without difficulty.

The center of the eclipse will traverse the hemisphere of the earth north of the solar path, always nearer to the pole of the ecliptic, in proportion to the inclination of the disk to the north. On the other hand, if the little disk inclines to the left semicircle, then the people south of the solar path will enjoy the spectacle of the total central eclipse.

But if the little disk remains neutral (inclining neither way) and remains halfway between the two sections of the circle, then the greatest solar eclipse will take place at the equator and those who live near the poles of the ecliptic will not enjoy a trace of that eclipse. This is because the half of the equatorial diameter enormously outmeasures even the greatest apparent semidiameters of the sun and of the moon, even taking as a norm the smallest horizontal parallax of the moon.

What has been said about the true new moon is to be understood also, proportionately, about the true full moon. For when, with respect to the equations of the centers, the moon shall be distant on the mechanism by a full semicircle from the sun (also in the heavens it will be truly in opposition to the sun) there will be a true full moon. Likewise, the moon in the heavens will be in eclipse if, at the time of opposition, the pointers of the little index (which we mentioned before) situated below the center of the clock are so far away from the belly of the dragon that they are forced to lie under the two smaller segments of the circle which, in all full moons, are always to be moved from the index of the synodic moon to the region of that little index. As a matter of fact, the closer the little pointers approach to the middle of the segments, the more obscured it will be.

You will know, furthermore, that the eclipse of the moon occurs in the head of the dragon if the disk of the little moon, attached to the other point of the little index, is raised to the head of the dragon; conversely, when the little disk of the moon inclines to the tail, the eclipse is taking place in the tail of the dragon.

And, accordingly, when you observe the little moon of the index inclined to one or other section of the circle, so also in the heavens, the eclipse of the moon is only partial and the northern or the southern part of the moon is illuminated.

The current time will indicate whether the lunar eclipse is visible or not. As the new moon ecliptic falls during the day, the eclipse will not be visible, since the earth denies a sight of the moon which is below the horizon. But, conversely, if there are no clouds, the eclipse will be visible anywhere, if the luminous bodies are ecliptically in opposition at night.

Since lunar eclipses appear to all people as being of the same magnitude and duration, and begin and dissipate at the same absolute moment of time, I decided to reveal another facet of this spectacle on the right side of the center of the clock (see chapter III above). There, at the time of the true ecliptic full moon, as the pointer of the third little index shows, you can ascertain the hours, etc., of duration, and the inches of greatest obscuration. The little moon attached to the index is a model of the actual eclipsed moon.

IX

Thus, with the aid of this machine, solar and lunar eclipses of the past can be recalled and future ones can be foreseen. Indeed, if the index of prime minutes is speeded up by hand, whose wheel imparts motion to the other indices and shields, then, the dials and openings will foretell the year, month, day, hour, etc., of any future eclipse. I foresaw that the times would thus be evolved too slowly, and that the clock wheels would be considerably worn by repeated experiments (if, for instance, by the rotation of the index of prime minutes, to whose period only a single hour corresponds, the future new and full moon ecliptics were being investigated). Therefore, I took care that the wheel which immediately communicates motion to the index of the synodic moon should be so fitted internally to the mechanism that by the reversal of any external index, the wheel would be removed from its proper position; whenever desired, it could be quickly and most accurately restored to its proper place.

In this way, since the close meshing of the wheels is released, you can extend the experiment for many years, even for many centuries. You have only to guide with your hand the index of the synodic moon on the circles, always intently observing whether, in the passage which this index makes over the little index, both pointers of the little index are hidden by the segments of the circle. Having observed this, look at the index moved by hand, for if this has carried the solar disk halfway between the two larger segments of the circle to the region of the hidden little index, then you will know that eclipse will be a solar eclipse. On the other hand, you will know that it will be a lunar eclipse, if the index (moved by hand) has carried the moon, situated between the two smaller segments of the circle, to the same region (i.e., the hidden part of the circle). The solar disk and the lunar disk alternately will reveal to you the circumstances of both eclipses. The current year will be given by the Julian period, reducible to any desired epoch, and, contained in the solar cycle, the golden number and the Roman cycle. The month of the year and also the day of the month will be indicated by the pointer of the little index, first on the right side of the clock. And what I have said of future eclipses should be equally understood of past eclipses, so long as the index, which can be moved either way at will, is moved in reverse.

Finally, though 55 wheels were employed to carry so many dials, all are driven by one source of power not exceeding the third part of a Germanic hundred-weight which, suspended at the geometric height of five feet (about the ordinary stature of a man), keeps the whole machine in operation for a hundred days and more.

Although the machine repeats hours and quarter hours at will and, consequently, the number of wheels and the rest of the apparatus necessary for these functions is thereby increased, it has not grown to an unwieldy size, however much one might erroneously imagine it to be. It does not exceed the bulk of ordinary clocks hanging from a wall; indeed, it scarcely equals these.

The entire machine, ready for operation, does not weigh more than 156 ounces, although it is made of steel or brass throughout and further weighted with two bells and a rather large brass dial-plate.

Of course, there are many more things to be said, especially about the mechanical structure of the wheels, but fearing to tire my kind reader unduly by exceeding the bounds of a summary, I am forced to put an end, though unwillingly, to this sufficiently shortened explanation of the work. I have hope of giving satisfaction to many more when I shall have communicated to the learned world another and completely new automatic work, grander than this present one. It is already theoretically completed in all its calculations, but still to be worked out mechanically from the very beginning, if but God, thrice Best and Greatest, bless the undertaking and mercifully grant life and health--to whom be in, and from, and through all things, all honor and glory in eternity and beyond.

BIBLIOGRAPHY

The following works have been used in compiling the material for this paper. They are frequently referred to in the text in shortened form.

AMBROSI, FRANCESCO. _Scrittori ed artisti Trentini._ Trent: Giovanni Zippel, 1883.

BONOMI, L. _Naturalisti, medici e tecnici Trentini._ Trent: privately printed, 1930.

BORGHESI, FRANCESCO. _Novissima ac Perpetua Astronomica Ephemeris Authomatica Theorico-Practica._ Trent: Giovanni Battista Monauni, 1763(?).

---- _Novissimum Theorico-Practicum Astronomicum Authoma Juxta Pariter Novissimum Mundi Systema._ Trent: Giovanni Battista Monauni, 1764.

ENGELMANN, MAX. Philipp Matthäus Hahn. Berlin: Verlag Fischer, 1923.

ESPOSTI, ALFREDO DEGLI. La sala 'Innocente Binda' al Museo della Scienza e della Tecnica di Milano. _La Clessidra_ (July 1960), anno 16, no. 7, pp. 18-21.

FRANCH, LEONE. _La Valle di Non._ Trent, 1953.

LLOYD, H. ALAN. _Some outstanding clocks over seven hundred years, 1250-1950._ London: Leonard Hill, 1958.

MOSNA, EZIO. _Trento._ Trent, 1914.

PERINI, AGOSTINO (compilatore). _Statistica del Trentino, Biblioteca Communale del Trentino._ Vol. 2, p. 57 (cons. 6, carta 9).

PIAMONTE, GUISEPPE. _La nauna descritta al viaggiattore._ Milan, 1829.

PIPPA, LUIGI. Antonio Bartolomeo Bertolla. _La Clessidra_ (January 1961), anno 17, no. 1, pp. 22-25.

SAN CAJETANO, DAVID À. _Praktische Anleitung für Künstler, alle astronomische Perioden durch brauchbare bisher noch nie gesehene ganz neue Räderwerke mit Leichtigkeit vom Himmel unabweichlich genau auszuführen, sammt Erweiterung der Theorie des neuen Rädergebäudes._ Vienna: privately printed, 1793.

TOVAZZI, GIANGRISOSTOMO. _Biblioteca Tirolese._ Vol. 2, art. 329, MS. 168, pp. 406-407. Trent, 1780.

VISCHER, GEORGE F. _Beschreibung mechanischer Kunstwerke, welche unter der Direktion und Anweisung M. Philipp Matth. Hahn, Pfarrers in Kornwestheim..._. Stuttgart: Mezler, 1774.

VON BERTELE, HANS. The development of equation clocks. _La Suisse Horologere_ (1959-1961), parts 1 through 5.

WENHAM, EDWARD. Tall case clocks. _The Antiquarian Magazine_ (May 1927), vol. 8, no. 4, p. 33. [The Borghesi clock is illustrated only from a photograph of the Anderson Art Galleries in New York, and mislabeled "Astronomical Clock made in Jena, 1656, in elaborate mahogany case."]

* * * * *

CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY:

PAPER 36

THE ENGINEERING CONTRIBUTIONS OF WENDEL BOLLMAN

_Robert M. Vogel_

EARLY CAREER 80

THE BOLLMAN TRUSS 85

W. BOLLMAN AND COMPANY 91

FINAL USE OF THE BOLLMAN TRUSS 95

KNOWN BOLLMAN WORKS 99

BIBLIOGRAPHY 104

_Robert M. Vogel_

THE ENGINEERING CONTRIBUTIONS OF WENDEL BOLLMAN

_The development of structural engineering has always been as dependent upon the availability of materials as upon the expansion of theoretical concepts. Perhaps the greatest single step in the history of civil engineering was the introduction of iron as a primary structural material in the 19th century; it quickly released the bridge and the building from the confines of a technology based upon the limited strength of masonry and wood._

_Wendel Bollman, self-taught Baltimore civil engineer, was the first to evolve a system of bridging in iron to be consistently used on an American railroad, becoming one of the pioneers who ushered in the modern period of structural engineering._

THE AUTHOR: _Robert M. Vogel is curator of civil engineering in the Smithsonian Institution's Museum of History and Technology._

Wendel Bollman's name survives today solely in association with the Bollman truss, and even in this respect is known only to a few older civil and railroad engineers. The Bollman system of trussing, along with those of Whipple and Fink, may be said to have introduced the great age of the metal bridge, and thus, directly, the modern period of civil engineering.

Bollman's bridge truss, of which the first example was built in 1850, has the very significant distinction of being the first bridging system in the world employing iron in all of its principal structural members that was used consistently on a railroad.

The importance of the transition from wood to iron as a structural and bridge building material is generally recognized, but it may be well to mention certain aspects of this change.

The tradition of masonry bridge construction never attained the great strength in this country which it held in Europe, despite a number of notable exceptions. There were several reasons for this. From the very beginning of colonization, capital was scarce, a condition that prevailed until well into the 19th century and which prohibited the use of masonry because of the extremely high costs of labor and transport. An even more important economic consideration was the rapidity with which it was necessary to extend the construction of railways during their pioneer years. Unlike the early English and European railways, which invariably traversed areas of dense population and industrial activity, and were thus assured of a significant financial return almost from the moment that the first rail was down, the Baltimore and Ohio and its contemporaries were launched upon an entirely different commercial prospect. Their principal business consisted not so much in along-the-line transactions as in haulage between principal terminals separated by great and largely desolate expanses. This meant that income was severely limited until the line was virtually complete from end to end, and it meant that commencement of return upon the initial investment was entirely dependent upon the speed of survey, graduation, tunneling, and bridging.

The need for speed, the general attenuation of capital, and the simple fact that all the early railroads traversed thickly forested areas rendered wood the most logical material for bridge and other construction, both temporary and permanent.

The use of wood as a bridge material did not, of course, originate with the railroads, or, for that matter, in this country. The heavily wooded European countries--Switzerland in particular--had a strong tradition of bridge construction in timber from the Renaissance on, and naturally a certain amount of this technique found its way to the New World with the colonials and immigrants.

America's highway system was meager until about the time the railroad age itself was beginning. However, by 1812 there were, along the eastern seaboard, a number of fine timber bridges of truly remarkable structural sophistication and workmanship.

It was just previous to the advent of the railroads that the erection of highway bridges in this country began to pass from an art to a science. And an art it had been in the hands of the group of skilled but unschooled master carpenters and masons who built largely from an intuitive sense of proportion, stress, and the general "fitness of things." It passed into an exact science under the guidance of a small number of men trained at first in the scientific and technical schools of Europe, and, after about 1820, in the few institutions then established in America that offered technical instruction.

The increasing number of trained engineers at first affected highway bridge construction not so much in the materials used but in the way they were assembled. In a bridge designed by a self-taught constructor, the cheapness of wood made it entirely feasible to proportion the members by enlarging them to the point where there could be no question as to their structural adequacy. The trained engineer, on the other hand, could design from the standpoint of determining the entire load and then proportioning each element according to the increment of stress upon it and to the unit capacity of the material.

By the time railroads had started expanding to the West there had been sufficient experience with the half dozen practical timber truss systems by then evolved, that there was little difficulty in translating them into bridges capable of supporting the initial light rail traffic.

In spite of its inherent shortcomings, wood was so adaptable that it met almost perfectly the needs of the railroads during the early decades of their intense expansion, and, in fact, still finds limited use in the Northwest.

Early Career

Wendel Bollman was born in Baltimore of German parents in 1814. His father was a baker, who in the same year had aided in the city's defense against the British. Wendel's education, until about the age of 11, was more or less conventionally gained in public and private schools in Baltimore. He then entered into informal apprenticeship, first to an apothecary in Sheperdstown, Virginia (now West Virginia), and then to one in Harpers Ferry. In 1826 or 1827 he became ill and returned to Baltimore for cure. From that time on his education was entirely self-acquired.

It is of interest, in light of his later career, to note that on the Fourth of July 1828, he marched with other boys in a procession that was part of the Baltimore and Ohio Railroad's cornerstone-laying ceremony. Shortly afterward, he apprenticed himself to a carpenter for a brief time, but when the work slacked off he obtained work with the B. & O. The right-of-way had been graded for about five miles by that time, but no rail was down. The boy was at first given manual work, but soon advanced to rodman and rapidly rose as he gained facility with the surveying apparatus. In the fall of 1829 he participated in laying the first track. As his mother was anxious that he continue his education in carpentry, he left the railroad in the spring of 1830 to again enter apprenticeship. He finished, became a journeyman, helped build a planter's mansion in Natchez, and returned to Baltimore in 1837 to commence his own carpentry business. The next year, while building a house in Harpers Ferry, he was asked to rejoin the B. & O. to rebuild parts of its large timber bridge over the Potomac there, which had fallen victim to various defects after about a year's use.

Shortly after the Harpers Ferry bridge reconstruction, Bollman was made foreman of bridges. It is apparent that, on the basis of his practical ability, enhanced by the theoretical knowledge gained by intense self-study, he eventually came to assist Chief Engineer Benjamin H. Latrobe in bridge design. He later took this work over entirely as Latrobe's attentions and talents were demanded in the location and extension of the line between Cumberland and Wheeling.

The B. & O. did not reach its logical destination, Ohio (actually Wheeling, West Virginia, on the east bank of the Ohio River) until 1853. In the years following Bollman's return to the railroad, the design of bridges was an occupation of the engineering staff second in importance only to the location of the line itself. During this time Bollman continued to rise and assume greater responsibilities, being appointed master of road by Latrobe in 1848. In this position he was responsible for all railroad property that did not move, principally the right-of-way and its structures, including, of course, bridges.

The recognition of Bollman's abilities was in the well-established tradition of the B. & O., long known as America's first "school of engineering," having sponsored many early experiments in motive power, trackwork, and other fundamental elements of railroad engineering. It furnished the means of expression for such men as Knight, Wright, Whistler, Latrobe, and Winans.

Of these pioneer civil and mechanical engineers, some were formally trained but most were self-taught. Bollman's career on the B. & O. is of particular interest not only because he was perhaps the most successful of the latter class but because he was probably also the last. He may be said to be a true representative of the transitional period between intuitive and exact engineering. Actually, his designing was a composite of the two methods. While making consistent use of mathematical analysis, he was at the same time more or less dependent upon empirical methods. For years, B. & O. employees told stories of his sessions in the tin shop of the railroad's main repair facility at Mount Clair in Baltimore, where he built models of bridges from scraps of metal and then tested them to destruction to locate weaknesses. It seems most likely, however, that the empirical studies were used solely as checks against the mathematical.

In the period when Bollman began designing--about 1840--there were fewer than ten men in the country designing bridges by scientifically correct analytical methods, Whipple and Roebling the most notable of this group. By 1884, the year of Bollman's death, the age of intuitive design had been dead for a decade or longer.

The B. & O. was in every way a truly pioneer enterprise. It was the first practical railroad in America; the first to use an American locomotive; the first to cross the Alleghenies. The spirit of innovation had been encouraged by the railroad's directors from the outset. It could hardly have been otherwise in light of the project's elemental daring.

The first few major bridges beyond the line's starting point on Pratt Street, in Baltimore, were of rather elaborate masonry, but this may be explained by the projectors' consciousness of the railroad's significance and their desire for permanence. However, the aforementioned economic factors shortly made obvious the necessity of departure from this system, and wood was thereafter employed for most long spans on the line as far as Harpers Ferry and beyond. Only the most minor culverts and short spans, and those only in locations near suitable quarries, were built of stone.

In addition to the economic considerations which prompted the company to revert to timber for the major bridges, there were several situations in which masonry construction was unsuitable for practical reasons. If stone arches were used in locations where the grade of the line was a relatively short distance above the surface of the stream to be crossed, a number of short arches would have been necessary to avoid a very flat single arch. In arch construction, the smaller the segment of a circle represented by the arch (that is, the flatter the arch), the greater the stress in the arch ring and the resulting horizontal thrust on the abutments.

The piers for the numerous arches necessary to permit an optimum amount of rise relative to the span would have presented a dangerous restriction to stream flow in time of flood. By the use of timber trusses such crossings could be made in one or two spans with, at the most, one pier in the stream, thus avoiding the problem.

The principal timber bridges as far west as Cumberland were of Latrobe's design. These were good, solid structures of composite construction, in which a certain amount of cast iron was used in joints and wrought iron for certain tension members. They were, however, more empirical than efficient and, for the most part, not only grossly overdesigned but of decidedly difficult fabrication and construction.

What is interesting about the Latrobian timber trusses, however, is the effect they appear to have had upon Bollman's subsequent work in the design of his own truss. This effect is evidenced by the marked analogy between the primary structural elements of the two types. The Latrobe truss at Elysville (fig. 2) was only partially a truss, inasmuch as the greater part of the load was not carried from panel to panel, finally to appear at the abutments as a pure vertical reaction, but was carried from each panel (except the four at the center) directly to the bearing points at the piers by heavy diagonal struts, after the fashion of the famous 18th-century Swiss trusses of the Grubenmanns. It was a legitimate structural device, and the simplest means of extending the capacity of a spanning system. However, it was defective in that the struts applied considerable horizontal thrust to the abutments, requiring heavier masonry than would otherwise have been necessary.

It is quite likely that Latrobe did not have absolute confidence in the various pure truss systems already patented by Town, Long, and others, and preferred for such strategic service a structure in which the panel members acted more or less independently of one another. It will be seen that, similarly, the individual panel loads in Bollman's truss were carried to the ends of the frame by members acting independently of one another.

The Bollman Truss

There had never been any question about the many serious inadequacies of wood as a bridge material. Decay and fire risk, always present, were the principal ones, involving continuous expenditure for replacement of defective members and for fire watches. It was, in fact, understood by the management and engineering staff of the B. & O. that their timber bridge superstructures, though considered the finest in the country, were more or less expedient and were eventually to be replaced. In this regard it is not surprising that Latrobe, a man of considerable foresight, had, at an early date, given serious thought to the possible application of iron here.

The world's first major iron bridge, the famed cast-iron arch at Coalbrookdale, England, had been constructed in 1779. Its erection was followed by rather sporadic interest in this use of the material. The first significant use of iron in this country was in a series of small trussed highway arches erected by Squire Whipple over the Erie Canal in the early 1840's, over 60 years later. In these, as in most of the earlier iron structures, an arch of cast iron was the primary support. The thrust of the arches was counteracted by open wrought-iron links with other wrought- and cast-iron members contributing to the truss action.

The Whipple bridges promoted a certain amount of interest in the material. In the B. & O.'s annual report for the fiscal year 1849 appears the first record of Latrobe's interest in this important matter. In the president's message is found the following, rather offhand, statement:

$6,183.19 have been expended toward the renewal of the Stone Bridges on the Washington Branch, carried off by the flood of Oct. 7th, 1847. Preparations are made and contracts entered into, for the reconstruction of the large Bridges at Little Patuxent and at Bladensburg which will be executed in a few months.... It is proposed to erect a superstructure of Iron upon stone abutments, at each place--with increased span, for greater security against future floods.

It is interesting to note that it was indeed Bollman trusses to which the president of the railroad had referred. How much earlier than this date Bollman had evolved his peculiar trussing system is not clear. The certain influence of Latrobe's radiating strut system of trussing has been mentioned. As likely an influence was another basic technique commonly used to increase the capacity of a simple timber beam--that of trussing--i.e., placing beneath the beam a rod of iron that was anchored at the ends of the beam and held a certain distance below it at the center by a vertical strut or post. This combination thus became a truss in that the timber portion was no longer subject to a bending stress but to a simple one of compression, the rod absorbing the tensile stress of the combination. The effect was to deepen the beam, increasing the distance between its extreme fibers and--by thus reducing the bending moment--reducing the stress in them (see fig. 3).

It apparently occurred to Bollman that by extending the number of rods in a longitudinal direction, this effect could be practically amplified to such an extent as to be capable of spanning considerable distances. He almost certainly did not at first contemplate an all-iron system, but rather a composite one such as described. It is entirely likely that such trussed beams, with multiple systems of tension rods, were used by Bollman as bridging in temporary trestlework along the line as early as 1845 (see fig. 4).

It is impossible to say whether Bollman himself, or Latrobe, was struck with the logic of further elaborating upon the system and, simultaneously, translating the timber compression member into one of cast iron. Cast iron would naturally have been selected for a member that resisted a compressive stress, as it was considerably cheaper than wrought iron. But more important, at that time wrought iron was not available in shapes of sufficient sectional area to resist the appreciable buckling stresses induced in long compression members. The cost of building up members to sufficient size from the very limited selection of small shapes then rolled would have been prohibitive.

The trussing rods, subjected to tension, were of wrought iron inasmuch as the sectional area had only to be sufficient to resist the primary axial stress.

The first all-iron Bollman truss was constructed over the Little Patuxent River at Savage Factory, near Laurel, Maryland, in 1850. In the chief engineer's report for the year 1850, Latrobe was able to state that the truss had been completed and was giving "much satisfaction." He went on at some length to praise the "valuable mechanical features" embodied therein, and expressed great confidence that iron would become as important a material in the field of civil engineering as it was in mechanical engineering.

The cost of this first major Bollman bridge was $23,825.00. Its span was 76 feet. Latrobe's confidence was well placed. The Savage span and another at Bladensburg may be considered successful pilot models, for, in spite of a certain undercurrent of mistrust of iron bridges within the engineering profession--due mainly to a number of failures of improperly designed spans--Latrobe felt there was sufficient justification for the unqualified adoption of iron in all subsequent major bridge structures on the B. & O.

Almost immediately following completion of the Savage Bridge, Bollman undertook the design of replacements for the large Patapsco River span at Elysville (now Daniels), Maryland, and the so-called Winchester span of the B. & O.'s largest and most important bridge, that over the Potomac at Harpers Ferry. Harpers Ferry bridge, a timber structure, had been designed by Latrobe and built in 1836-1837 by the noted bridge constructor Lewis Wernwag. It was peculiar in having a turnout, near the Virginia shore, whereby a subsidiary road branched off to Winchester (see fig. 6). Only the single span on this line, situated between the midriver switch and the shore, was slated for replacement, as the other seven spans of the bridge had been virtually reconstructed in the decade or so of their history and were in sound condition at the time.

The Winchester span (fig. 8), which was the first Bollman truss to embody sufficient refinement of detail to be considered a prototype, was completed in 1851. Bollman was extremely proud of the work, with perfect justification it may be said. The 124-foot span was fabricated in the railroad's extensive Mount Clair shops. It was subdivided into eight panels by seven struts and seven pairs of truss rods. An interesting difference between this span and Bollman's succeeding bridges was his use of granite rather than cast iron for the towers. The span consisted of three parallel lines of trussing to accommodate a common road in addition to the single-track Winchester line.

The distinctive feature of the Bollman system was the previously mentioned series of diagonal truss links in combination with a cast-iron compression chord, which Bollman called the "stretcher." The spacing between the chord and the junction of each pair of links was maintained by a vertical post or strut, also cast.

Much of the appeal of this design lay unquestionably in the sense of security derived from the fact that each of the systems acted independently to carry its load to the abutments. The lower chords, actually nonfunctional in the primary structure, were included merely to preserve the proper longitudinal spacing between the lower ends of the struts. A certain lack of rigidity was inherent in the system due to that very discontinuity which characterized its action; however, this was compensated for by a pair of light diagonal stay rods crossing each panel. These rods served the additional function of distributing concentrated loads to adjacent struts much in the manner of the bridging between floor joists in a building.

In the Winchester span the floor system was of timber for reasons of economy. This was a very minor weakness inasmuch as any stick could be quickly replaced, and without disturbing the function of the structure. Bollman received a patent for his truss in January 1852, and in the same year published a booklet describing his system in general and the Harpers Ferry span in particular. Here, he first calls it a "suspension and trussed bridge," which is indeed an accurate designation for a system which is not strictly a truss because it has no active lower chord. (The analogy to a suspension bridge is quite clear, each pair of primary rods being comparable to a suspension cable.) Thereafter, Bollman's invention was generally termed a suspension truss.

INFLUENCE OF THE TRUSS

Bollman's 1852 publication was widely disseminated here and abroad and studied with respectful interest by the engineering profession. Its drawings of the structure were copied in a number of leading technical journals in England and Germany. Although there is no record that the type was ever reproduced in Europe, there can be little doubt that this successful structural use of iron by the most eminent railroad in the United States and its endorsement by an engineer of Latrobe's status gave great impetus to the general adoption of the material. This influence was certainly equal to that of Stephenson's tubular iron bridge of 1850 over the Menai Strait, or Roebling's iron-wire suspension bridge of 1855 over Niagara gorge. The Bollman design had perhaps even greater influence, as the B. & O. immediately launched the system with great energy and in great numbers to replace its timber spans; on the other hand, Roebling's structure was never duplicated in railroad service, and Stephenson's only once.

EVALUATION OF THE TRUSS

By the late 1850's iron was well established as a bridge material throughout the world. Once the previous fears of iron had been stilled and the attention of engineers was directed to the interpretation of existing and new spanning methods into metal, the Bollman truss began to suffer somewhat from the comparison. Although its components were simple to fabricate and its analysis and design were straightforward, it was less economical of material than the more conventional panel trusses such as the Pratt and Whipple types. Additionally, there was the requisite amount of secondary metal in lower chords and braces necessary for stability and rigidity.

A factor difficult to assess is Bollman's handling of his patent, which was renewed in 1866. There is sufficient evidence to conclude that he considered the patent valuable because it was based upon a sound design. Therefore, he probably established a high license fee which, with the truss's other shortcomings, was sufficient to discourage its use by other railroads. As patron, the B. & O. had naturally had full rights to its use.

An additional defect, acknowledged even by Bollman, arose because of the unequal length of the links in each group except the center one. This caused an unevenness in the thermal expansion and contraction of the framework, with the result that the bridges were difficult to keep in adjustment. This had the practical effect of virtually limiting the system to intermediate span lengths, up to about 150 feet. For longer spans the B. & O. employed the truss of another of Latrobe's assistants, German-born and technically trained Albert Fink.

The Fink truss was evolved contemporaneously with Bollman's and was structurally quite similar, being a suspension truss with no lower chord. The principal difference was the symmetry of Fink's plan, which was achieved by carrying the individual panel loads from the panel points to increasingly longer panel units before having them appear at the end bearings. This eliminated the weakness of unequal strains. The design was basically a more rational one, and it came to be widely used in spans of up to 250 feet, generally as a deck-type truss (see fig. 11).

W. Bollman and Company

Bollman resigned from the Baltimore and Ohio in 1858 to form, with John H. Tegmeyer and John Clark, two of his former B. & O. assistants, a bridge-building firm in Baltimore known as W. Bollman and Company. This was apparently the first organization in the United States to design, fabricate, and erect iron bridges and structures, pioneering in what 25 years later had become an immense industry. The firm had its foundation at least as early as 1855 when advertisements to supply designs and estimates for Bollman bridges appeared over Tegmeyer's name in several railroad journals (see fig. 12).

Bollman's separation from the B. & O. was not a complete one. The railroad continued its program of replacing timber bridges with Bollman trusses, and contracted with W. Bollman and Company for design and a certain amount of fabrication. There is some likelihood that eventually fabrication was entirely discontinued at Mount Clair, and all parts subsequently purchased from Bollman.

The firm prospered, erecting a number of major railroad bridges in Mexico, Cuba, and Chile. Operations ceased from 1861 to 1863 because of difficult wartime conditions in the border city of Baltimore. Following this, Bollman reentered business as sole proprietor of the Patapsco Bridge and Iron Works.

The most noteworthy of Bollman's works in this period was a series of spans at Harpers Ferry. The B. & O.'s timber bridge had been destroyed by Confederate forces in June 1861, and the crossing was thereafter made upon temporary trestlework. This was a constant source of trouble, with continuing interruptions of the connection from high water, washouts, and military actions. The annoyance and expense of this became so great that the company decided to risk an iron bridge at the crossing. In July and August 1862, two sections of Bollman truss, spans no. 4 and no. 5 were completed. As this occurred during the time when W. Bollman and Company was inoperative, the work was produced at Mount Clair to Bollman's design and, undoubtedly, erected under his supervision. Five weeks later, on September 24, these and Bollman's famous Winchester span of 1851 were blown up by the Confederates, and the line's business was again placed at the mercy of trestling.

The spirit of the B. & O. administration indeed seems to have been unshakable when, in the face of such heartbreaking setbacks, it determined to again bridge the river with iron, even at the height of the hostilities. In November, span no. 5 was erected, and by April 1863 nos. 3, 4, and 6 also. These were the four straight spans in midriver between the "wide" (or "branch," or "wye") span and the span on the Maryland shore over the Chesapeake and Ohio Canal (see fig. 13). Although the wood floor system of these spans was burned for strategic reasons by U.S. troops later in 1863, they survived the war.

In 1868 the remaining trestlework was replaced with Bollman trusses. This magnificent structure served the railroad until 1894 when the right-of-way was realigned at Harpers Ferry. However, the half used by the common road remained in use until carried away by the disastrous flood in 1936. The piers may still be seen.

During the prewar years, Bollman evolved a structural development of most profound importance, which is usually associated with the Phoenix Iron Works and its founder, Samuel J. Reeves. In the erection of a high trestlework viaduct for the Havana Railroad, Bollman apparently became concerned with the tensile weakness of cast iron when applied in long, unsupported columns. Although a column is normally subjected to compressive stresses, when the slenderness ratio--that is, the length divided by the radius of gyration of the cross section--becomes great, a secondary bending stress may be produced. If this stress becomes great enough, the value of the tensile stress in one side of the column may actually exceed the principal compressive stress, and a net effect of tension result.

As already mentioned, the few available rolled-iron shapes were of relatively small area and quite unsuitable for use as columns unless combined and built up in complex fabrications. The normal practice at the time was to use cast compression members in iron bridges and structures, with their sectional area so proportioned to the length that a state of tension could not exist. In the case of long members, this naturally meant that an excessive amount of material was used.

Bollman was conscious of the problem from his experience with the stretchers and struts of his truss, and he must have been aware of the great advantage which would be obtained by a practical method of forming such members in wrought iron, the tensile resistance of which is equivalent to the compressive. He eventually developed the forerunner of what came to be known as the Phoenix form by having special segmental wrought-iron shapes rolled by Morris, Tasker and Company of Philadelphia, these shapes being combined into a circular section with outstanding flanges for riveting together. The circular section is theoretically the most efficient to bear compressive loading. A column of any required diameter could be produced by simply increasing the number of segments, the individual size of which never exceeded contemporary rolling mill capacity (see fig. 16).

The design exhibits the inspired combination of functional perfection and simplicity that seems to characterize most great inventions.

It may have been because he had no facilities for rolling that Bollman communicated his idea to Reeves, although this seems illogical. At any rate, Reeves and his associates patented the system extensively, and the Phoenix column was eventually employed to the virtual exclusion of cast-iron and other types of wrought-iron columns. By the end of the 19th century it began to pass from use, as mills became capable of producing larger sections with properties relatively favorable to column use and more adaptable to connection with other members.

Final Use of the Bollman Truss

The Bollman truss found occasional use elsewhere than on the B. & O. lines, but generally only when erected on contract by Patapsco Bridge and Iron Works. However, the fact that Bollman could profitably erect this bridge in the severely competitive 1870's indicates that the harsh criticism of the system by authorities of such stature as Whipple was not necessarily justified. Bollman's advertisements, in fact, refer to the favorable recommendations of other such renowned engineers as Herman Haupt and M. C. Meigs.

An interesting application of the system was in a drawbridge, formed of two Bollman deck spans, over an arm of the Mississippi at Quincy, Illinois (see fig. 17). The first iron bridge in Mexico was erected by Bollman over the Medellín River about 1864. Another work of this period, which attracted considerable attention, was a pair of bridges that Bollman erected over North Carolina's Cape Fear River in 1867-1868. These bridges were notable for their foundation on cast-iron cylinders, sunk pneumatically. This was one of the first instances of the use of the process in America, and the depth of 80 feet below the water surface reached by one cylinder was considered remarkable for years afterward.

In the last active decade or so of his career, Bollman produced hundreds of minor bridges and other structures. In 1873 he supplied the castings for the splendid iron dome of Baltimore's City Hall and erected the ingenious water-main truss which carries Lombard Street over Jones Falls in that city. In this structure the top and bottom chords of the central line of trussing are cast-iron water mains, bifurcated at the abutments, and joined by cast- and wrought-iron web members (see fig. 20).

In the mid 1870's Bollman saw his truss pass into obsolescence. This was due primarily to the generally increasing distrust of cast iron for major structural members due to its brittleness, but advances in structural theory, availability of a greater variety of rolled structural shapes, and the increasing loading patterns of the period all contributed.

Although no Bollman trusses were built by Bollman or the B. & O. after 1875, those in use were only removed as required by heavier motive power. The Harpers Ferry span, as noted, remained in full main-line service until 1894. Bollman trusses on feeder lines were continued in use until much later; a number of them on the Valley Railroad of Virginia (see fig. 22) were not removed until 1923. However, only on the most isolated spurs was the Bollman truss permitted to reach really ripe age. The sole known remaining example (fig. 23) stands on such a branch--ironically, at Savage, over the Little Patuxent, the site of the first Bollman span. This is not the 1850 bridge, but one built in 1852 and moved to the present site 30 years later. The fate of the first span is not known.

Known Bollman Works

(All B. & O. works listed were designed by Bollman and built by the railroad, unless otherwise indicated.)

Dates of Location Type No. spans Remarks service / length of each

1850-? Savage, Md., Little Bollman 1/76' First Bollman truss Patuxent River through erected; granite towers; truss cost, $23,825. B. & O. RR.

1851-? Bladensburg, Md., Bollman 1/? Second Bollman truss Anacostia River through erected; granite towers; truss cost, $19,430. B. & O. RR.

1851-1862 Harpers Ferry, Va., Bollman 1/124' Winchester span; first Potomac River through major Bollman truss; three truss lines of truss; granite towers; blown up by Confederate Army on September 24, 1862. B. & O. RR.

1851-? Baltimore, Md., Trestle -- Wood trestle bents with Carey Street wrought-iron diagonals. First use of iron structural members in trestlework. Total length 76 feet. B. & O. RR.

1852- Savage, Md., Little Bollman 2/±80' Still standing. Moved to Patuxent River through Savage in 1888; original truss location unknown. This and succeeding Bollman trusses use iron towers. B. & O. RR.

1852 (or Marriottsville, Bollman 1/50' One of first Bollman 1853)-? Md., Patapsco River truss trusses with iron towers. B. & O. RR.

1853-? Zanesville, Ohio, Bollman 4/124' Double track, Central Ohio Muskingum River truss (or RR. Designed by Bollman; 5/160') built by Douglas, Smith & Co., Zanesville.

1854- Elysville (now Bollman 3/97'9" Upper bridge, skew. Cost, 1870(?) Daniels), Md., through $24,477.59. B. & O. RR. Patapsco River truss

1854-1862 Monocacy, Md., Bollman 3/119' Blown up September 8, Monocacy River truss 1862; rebuilt in 1864. Cost, $22,722.59. B. & O. RR.

1854-? Eastern Ohio Bollman 1/40' C. O. RR. Section 76 truss(?) adjacent to 300-ft. tunnel.

1855-? Bridgeville, Ohio, Bollman 1/71' C. O. RR. Salt Creek deck truss

Pre-1855-? Buffalo, N.Y. -- -- Unidentified. Mentioned by George Vose in Railroad Advocate (June 9, 1855).

1856-? Elysville, Md., Bollman 3/111' Lower Bridge. B. & O. RR. about 1-1/4 miles through east of 1854 truss bridge, Patapsco River

Pre-1856-? Marriottsville, Bollman 1/48'9" Referred to as "Tunnel Md. truss(?) Bridge" in B. & O. RR. annual report, 1856.

1856-? Near Ijamsville, "Iron 3/23'9" Possibly trussed beams; Md., Bush Creek girders" mentioned in B. & O. RR. annual report, 1856.

1856-? Near Ijamsville, "Iron 2/23'9" As above. Md., Bush Creek girders"

1856- North Branch, Md., Bollman 3/142' Partially destroyed in c.1862 Potomac River deck truss Civil War. B. & O. RR.

1860-1906 Chile, Angostura Bollman 4/115' Chilean Railways. River truss(?) Designed and built by Bollman. Replaced by bridge built by French firm of Schneider, Cruesot & Co.

1860-1910 Chile, Paine River Bollman 1/? As above. truss(?)

Post- Ilchester, Md., Bollman 1/? B. & O. RR. 1860-? Patapsco River through truss

Pre-1861-? Cuba Bridges -- All bridges on Havana and RR., including iron station station house and bridge house at Guines. Designed and built by Bollman.

Pre-1861-? Cuba Bridges -- All bridges on Cienfuegos RR., Cárdenas RR., and Havana & Matanzas RR. Designed and built by Bollman.

Pre-1861-? Cuba Trestle -- Trestle with wrought-iron columns (the first such ever constructed). Havana RR. Designed and built by Bollman.

1862-1862 Harpers Ferry, Va., Bollman 2/160' Span no. 3 (July 24) and Potomac River through span no. 4 (August 21). truss Blown up September 24, 1862. B. & O. RR.

1862-1936 Harpers Ferry, Va., Bollman 1/160' Span no. 5 (November). Potomac River through B. & O. RR. truss

1863-1936 Harpers Ferry, Va., Bollman 3/160' Spans nos. 3, 4, and 5. Potomac River through Constructed previous to truss April 1863. B. & O. RR.

1863-? Berwyn, Md., Paint Bollman ? Iron bridge mentioned in Branch truss(?) B. & O. RR. annual report, 1863.

1863(4?)-? Clinton, Iowa, Pivot 1/360' Built by Detroit Bridge Mississippi River draw & Iron Works. It was the longest in the world at time of completion. Designed by Bollman.

1864-? Laurel, Md., Bollman ? Replaced stone arch that Patuxent River truss had been washed out. B. & O. RR.

c. 1864-? Near Veracruz, Bollman 1/115' Veracruz & Jucaro RR. Mexico, Medellín through First iron bridge in River truss Mexico. Designed and built by Bollman.

1864-? Near Point of Bollman 1/80'(?) Iron bridge mentioned in Rocks, Md., Back truss(?) B. & O. RR. annual Creek report, 1864. The span length given is that of previous stone arch.

1864-? Bladensburg, Md., Bollman 1/? Span for second track, to Anacostia River truss match 1851 span. B. & O. RR.

1868-? Cape Fear, N.C., Bollman 2/146'6" Wilmington Railway Bridge Northeast Branch, truss(?) 1/164' Co. This bridge was Cape Fear River pivot connected to that over draw/150' the Northwest Branch by 2-1/2 miles of timber trestling. Designed and built by Bollman.

1868-? Cape Fear, N.C., Bollman 1/217'(?) See above. Northwest Branch, truss(?) pivot Cape Fear River draw/150'

1868-? Quincy, Ill., Bollman 4/85' Chicago, Burlington & Quincy Bay (in deck pivot Quincy RR. The pivot draw Mississippi River) truss draw/190' was formed of two 85-ft. simple Bollman deck spans whose outer ends hung from hog chains. Designed by Bollman; built by Detroit Bridge & Iron Works.

1869- Baltimore, Md., Warren 2/100' North Avenue Bridge. c.1892 over Jones Falls, truss 2/55'6" Composite double B. & O. RR., and intersection truss; Northern Central timber top chord and RR. posts, wrought-iron lower chord and ties. In 55-ft. spans, both chords timber. Cost, $73,588. Built by Bollman.

c.1869- Harpers Ferry, Va., Bollman 4/? Canal span (no. 8), Wide 1936 Potomac River through span (no. 2), Winchester truss span, and West End span. Destroyed by flood in 1936. B. & O. RR.

1870- Baltimore, Md., Iron 1/108' Charles Street Bridge. c.1895 Jones Falls "Isometrical Three lines of trussing. truss" Cost, $20,297. Built by (probably Bollman. Pratt type)

1870- Bellaire, Ohio- Bollman 9/107'- In approaches; 2 spans on 1893 & Benwood W. Va., deck 125' Ohio side; 7 on West 1900 Ohio River truss Virginia side. B. & O. RR.

1870- Belpre, Ohio- Bollman 16/? In approaches; 7 spans on c.1895 Parkersburg, W. deck Ohio side; 9 on West Va., Ohio River truss Virginia side. B. & O. RR.

1870-? Elysville, Md., Bollman 4/? Skew; replacement of Patapsco River through Upper Bridge(?). B. & O. truss RR.

1871- Baltimore, Md., Timber ? Decker Street (now c.1895 Jones Falls and iron Maryland Avenue) Bridge. truss Cost, $24,975. Built by Bollman.

1871- Baltimore, Md., Warren 1/100' North Avenue Bridge. c.1892 over Northern truss Composite double Central RR. at intersection truss; Jones Falls cast-iron top chord and posts; wrought-iron bottom chord and ties. West span. Built by Bollman.

1873-1923 Cave Station, Va., Bollman 1/98'7" Valley Railroad of Middle River deck 1/63'5" Virginia (B. & O.) Bridge truss no. 120. The main span was a Whipple deck truss. Replaced with plate girders. Designed by Bollman.

1873-1923 Mount Crawford, Bollman 2/98'6" Valley Railroad of Va., North River deck 1/148'9" Virginia (B. & O.) Bridge truss no. 117. Designed by Bollman.

1873-1923 Verona, Va., North Bollman 3/98'7" Valley Railroad of River deck Virginia (B. & O.) Bridge truss no. 129. The main span was a 147-ft. Whipple deck truss. Designed by Bollman.

1873-? Wadesville, Va., Bollman 1/147'8" Span length given is that Opequon Creek through of previous wood span truss that burned in 1862. B. & O. RR.

c. 1873- Baltimore, Md. Iron roof ? First Presbyterian trusses Church. Built by Bollman; possibly designed by him.

1873- Baltimore, Md. Cast-iron City Hall. Cost, $12,840. stairs Designed by George A. Frederick, architect; built by Bollman.

1873- Baltimore, Md. Cast-iron Dome of the City Hall. framework Cost, $70,525. Designed by George A. Frederick; built by Bollman.

1875- Baltimore, Md., Iron truss 1/? Fayette Street Bridge. c.1913 Jones Falls Cost, $9,396. Built by Bollman.

1876- Baltimore, Md., "Single- 1/? Canton Avenue (now Fleet c.1913 Jones Falls beam iron Street) Bridge. Cost, bridge" $8,904. Built by Bollman. (truss?)

1876- Baltimore, Md., "Single- 1/? Eastern Avenue Bridge. c.1913 Jones Falls beam iron Cost, $12,382. Built by bridge" Bollman. (truss?)

1877- Baltimore, Md., Pratt and 1/88'6" Lombard Street Bridge. Jones Falls bowstring Three lines of truss; truss two outer trusses, composite cast- and wrought-iron polygonal Pratt type; center composite bowstring with Pratt-system web. Both chords are cast-iron water mains, bifurcated at the end bearings; cast-iron posts and wrought-iron ties. In service. Cost, $7,632. Designed by Jas. Curran, Baltimore water department; built by Bollman.

1877- Baltimore, Md., Iron truss 1/? Bath Street Bridge. Cost, c.1913 Jones Falls $4,172. Built by Bollman.

1879-? Baltimore, Md. Drawbridge 1/? Over entrance to City Dock. Cost, $13,182. Built by Bollman.

1879- Baltimore, Md., Warren 2/173'9" North Street (now c.1930 over Jones Falls truss Guilford Avenue) Bridge. and railroad Composite trusses; tracks cast-iron top chord and end posts; wrought-iron bottom chord and web members. Cost, $38,772.45. Built by Bollman; designed by Latrobe.

1881-1960 Baltimore, Md., Wrought- 1/? Union Avenue Bridge. (Woodberry), iron Pratt Built by Bollman; Jones Falls truss possibly designed by him.

?-? Harpers Ferry, Va., Bollman 1/148' Arsenal Branch, B. & O. Arsenal Canal through RR. Skew type. Span truss length is that of previous timber span.

?-? Baltimore, Md., Bollman 2/? B. & O. RR. Gwynns Falls through truss

BIBLIOGRAPHY

_A history and description of the Baltimore and Ohio Railroad by a citizen of Baltimore._ Baltimore, 1853.

Baltimore and Ohio Railroad Company. _A list of the officers and employees of the Baltimore and Ohio Railroad for November, 1857._ Baltimore, 1857.

----. _Third annual report of the president and directors to the stockholders of the Baltimore and Ohio Rail Road Company._ Baltimore: 1829. (Also the fourth through 38th annual reports. Baltimore, 1830-1864.)

----. _Baltimore and Ohio exhibits at the Century of Progress._ Chicago, 1934.

_Biographical cyclopedia of representative men of Maryland and the District of Columbia._ Baltimore, 1879.

BOLLMAN, WENDEL. _Iron suspension and trussed bridge as constructed for the Baltimore and Ohio Rail Road Co. at Harper's Ferry, and on the Washington branch of this road._ Baltimore, 1852.

----. Letter to John W. Garrett dated June 17, 1862. In files of Division of Mechanical and Civil Engineering, United States National Museum, Washington, D.C.

----. _Report of Mr. Bollman in relation to Central Ohio Rail Road._ Baltimore, 1854.

BRYANT, WILLIAM C. _Picturesque America._ New York, 1874.

CLARKE, THOMAS CURTIS. _An account of the iron railway bridge across the Mississippi River at Quincy, Illinois._ New York, 1869.

COLBURN, ZERAH. American iron bridges. _Minutes of the proceedings of the Institution of Mechanical Engineers_ (1863), vol. 22, pp. 540-573.

CONDIT, CARL. _American building art:--The nineteenth century._ New York: Oxford Press, 1960.

GRAY, GEORGE E. Notes on early practice in bridge building. _Transactions of the American Society of Civil Engineers_ (1897), vol. 37, pp. 2-16.

GREINER, JOHN E. The American railroad viaduct--Its origin and evolution. _Transactions of the American Society of Civil Engineers_ (1891), vol. 25, pp. 349-372.

LANG, PHILIP GEORGE. Bollman trusses on Valley of Virginia Branch will soon be memories. _Baltimore and Ohio Magazine_ (October 1923), pp. 18-19.

----. The old Baltimore and Ohio bridge crossing the Potomac River at Harpers Ferry, West [sic] Virginia. _Engineering News-Record_ (September 17, 1931), p. 446.

MALEZIEUX, EMILE. _Travaux publics des Etats-Unis d'Amerique en 1870._ Paris, 1873.

MCDOWELL, W. H. Unpublished engineer's report to the president and directors of Wilmington Railway Bridge Company, Wilmington, North Carolina, dated March 12, 1868. Typewritten copy in files of Division of Mechanical and Civil Engineering, U.S. National Museum, Washington, D.C.

SMITH, CHARLES SHALER. _Comparative analysis of the Fink, Murphy, Bollman and triangular trusses._ Baltimore, 1865.

SMITH, WILLIAM P. _The book of the great railway celebrations of 1857._ Baltimore, 1858.

TYRRELL, HENRY G. _History of bridge engineering._ Chicago, 1911.

WHIPPLE, SQUIRE. _Bridge building._ Albany, New York, 1869.

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CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY:

PAPER 37

SCREW-THREAD CUTTING BY THE MASTER-SCREW METHOD SINCE 1480

_Edwin A. Battison_

_Edwin A. Battison_

SCREW-THREAD CUTTING BY THE MASTER-SCREW METHOD SINCE 1480

_Among the earliest known examples of screw-thread cutting machines are the screw-cutting lathe of 1483, known only in pictures and drawings, and an instrument of the traverse-spindle variety for threading metal, now in the Smithsonian Institution, dating from the late 17th or early 18th century. The author shows clearly their evolution from something quite specialized to the present-day tool. He has traced the patents for these instruments through the early 1930's and from this research we see the part played by such devices in the development of the machine-tool industry._

THE AUTHOR: _Edwin A. Battison is associate curator of mechanical and civil engineering in the Smithsonian Institution's Museum of History and Technology._

Directness and simplicity characterize pioneer machine tools because they were intended to accomplish some quite specialized task and the need for versatility was not apparent. History does not reveal the earliest forms of any primitive machines nor does it reveal much about the various early stages in evolution toward more complex types. At best we have discovered and dated certain developments as existing in particular areas. Whether these forms were new at the time they were first found or how widely dispersed such forms may have been is unknown. Surviving evidence is in the form of pictures or drawings, such as the little-known screw-cutting lathe of 1483 (fig. 1) shown in _Das mittelalterliche Hausbuch_.

This lathe shows that its builder had a keen perception of the necessary elements, reduced to bare essentials, required to accomplish the object. Present are the coordinate slides often credited to Henry Maudslay. His slides are not, of course, associated with the spindle; neither is there any natural law which compels them to guide the tool exactly parallel with the axis of revolution. In this sense the screw-cutting lathe in the _Hausbuch_ is superior because it is in harmony with natural law and can generate a true cylinder, whereas Maudslay's lathe can only transfer to the work whatever accuracy is built into it.

In principle this machine shown in the _Hausbuch_ is very advanced as we see when we follow the design through to the present time. The artist, whose drawings give us our only knowledge of the machine, himself was obviously not very familiar with the details of its function. Reference to figure 1 shows that the threads on the lead screw and on the work, wind in opposite directions. This must be an error in delineation since the two are closely coupled together without any intervening mechanism so that the only possible result on the work must be a thread winding in the same direction as on the original screw. The work also is shown threaded for its entire length; this cannot be accomplished with any one location of the cross-slide. We are left with the question of whether this slide was used in two locations or whether the artist, possibly working from notes or an earlier rough sketch, failed to show an unthreaded portion on one end or the other of the work.

Of at least equal importance with the lead screw and work and their relationship to each other is the tool-support with its screw-adjusted cross-slide (fig. 2). Just how this was attached to the frame of the machine so that it placed the tool at a suitable radius is again a questionable point. The very well-developed cutting tool is sharpened to a thin, keen edge totally unsuited for cutting metal but ideal for use on a softer, fibrous substance: undoubtedly wood, in this instance. Unfortunately, the angle at which the artist chose to show us this cutter is not a view from which it is possible to judge whether or not the tool has been made to conform to the helix angle of the thread to be cut. This cross-slide, in conjunction with the traversing work spindle, gives us a machine having two coordinate slides yielding the same effect as the slide rest usually attributed to Henry Maudslay at the end of the 18th century. Actually, an illustration of coordinate slides independent of the spindle had been published as early as 1569 by Besson[1] and knowledge of them widely disseminated by his popular work on mechanics. These slides are shown as part of a screw-cutting machine with a questionably adequate connection, by means of cords, between the master screw and the work.

It was the author's pleasure recently to obtain for the Smithsonian Institution and identify a small, nicely made, brass instrument which had been in two collections in this country and one collection in Germany as an unidentified locksmith's tool (fig. 3). This proved to be an instrument of the traverse-spindle variety for threading metal. Fortunately, all essential details were present including a cutter (A in figure 4); this instrument was identified by the signature "Manuel Wetschgi, Augspurg." The Wetschgis were a well-known family of gunsmiths and mechanics in Augsburg through several generations. Two bore the given name Emanuel: the earlier was born in 1678 and died in 1728. He was quite celebrated in his field of rifle making and became chief of artillery to the Landgrave of Hesse-Kassel shortly before his death in his 51st year. Little is known of the later Emanuel Wetschgi except that he was at Augsburg in 1740. Tentative attribution of the instrument has been made to the earlier Emanuel, chiefly on the basis of his recognized position as an outstanding craftsman.

In several respects this little machine differs from its predecessor of the _Hausbuch_, as might be expected when allowance is made for the generations of craftsmen who undoubtedly worked with such tools over the roughly 200 years of time separating them. Another factor to consider when comparing these two machines is that one was used on metal, the other probably only on wood. Therefore, it is not surprising to find on the later machine an outboard or "tailstock" support for the work. The spindle of this support has to travel in unison with the work-driving spindle so that it is not an unexpected discovery to find that it is spring-loaded. Figure 5 shows how this spring may be adjusted to accommodate various lengths of work by moving the attachment screw to various holes in both the spring and in the frame. Also visible in the same illustration is a rectangular projection at the other end of the spring which engages a mating hole in the "tailstock" spindle to prevent its rotation.

Figure 6 shows the traversing spindle and nut removed from the machine. Provision has been made for doing this so easily that there is every reason to believe that, originally, there were various different spindle and nut units which could be interchangeably used in the machine. Additional evidence tending to support this concept exists in the cutting tool (fig. 4), which must have been intended for serious work as it has been carefully fitted in its unsymmetrical socket. The cutting blade of this tool, which works with a scraping rather than a true cutting action, is too wide to form a properly proportioned thread when used with the existing lead screw. This may well indicate that the tool was made for use with a lead of coarser pitch, now lost.

Perhaps the most startling feature of this machine when compared with the machine of the _Hausbuch_, is the absence of a cross-slide for adjusting the tool. Possibly this can be explained by the blunt scraping edge on the tool. In actual use, recently, to cut a sample screw, using a tool similar to the one found in the machine (fig. 7), it was found advantageous to be free of a cross-slide and thus be able to feed the tool into the work by feel rather than by rule, as would be done with a slide rest. In this way, it was possible to thread steel without tearing, as the cutting pressure could readily be felt and the tool could release itself from too heavy a cut. Size on several screws could be repeated by setting the tool to produce the desired diameter when its supporting arm came to rest against the frame of the machine. The screws used in the machine itself were apparently made in just such a way. They were not cut with a die as the thread blends very gradually into the body of the screw without the characteristic marks left by the cutting edges of a die. Threads cut with a single-point tool controlled by a cross-slide usually end even more abruptly than those cut by a die, while it would be quite simple with a machine of the nature we are considering to bring the thread to a gentle tapering end as seen in figure 8 (another view of the screw A in fig. 3) by gradually releasing the pressure necessary to keep the tool cutting as the end of the thread was approached.

That machines of this general type having the lead screw on the axis of the work were competitive with other methods and other types of machines over a long period of time may be seen from figures 9 and 10. The machine, left front in figure 9 and in more intimate detail in figure 10, can be seen to differ little from that shown in _Das mittelalterliche Hausbuch_ of 1483. The double work-support is, of course, a great improvement, while the tool-support is regressive since it lacks a feed screw.

The development of engineering theory, coupled with the rising needs of industry, particularly with the advent of the Industrial Revolution, brought about accelerated development of screw-cutting lathes through the combination of screw-cutting machines with simple lathes as seen in figure 9 and in detail in figure 11. One important advance shown here is driving the machine by means of a cord or band so that any means of rotary power could be applied, not just hand or foot power. Of greater interest and technical importance to this study is the provision, seen to better advantage in figure 11, for readily changing from one master lead screw to another. This had already been achieved in the Manuel Wetschgi machine, as far as versatility is concerned, although not in quite such a convenient way.

Figure 12, the headstock of another and more advanced lathe than shown in figures 9 and 11 but of the same type, shows "keys" (D), each of which is a partial nut of different pitch to engage with a thread of mating pitch. The dotted lines in figure 13 show the engaged and disengaged positions of one of these keys, and figure 14 shows the spindle with the various leads, C. At D is a grooved collar to be engaged by the narrow key shown in operating position at the left in figure 12 for the purpose of controlling the endwise movement of the spindle when used for ordinary turning instead of thread-cutting. In return for greater convenience and freedom from the expense of the many separate spindles, as typified by the Wetschgi machine, a sacrifice has been made in the length of the thread which can be cut without interruption.

This reduction in the length that could conveniently be threaded was no great drawback on many classes of work. This can be realized from figure 16 which shows a traverse-spindle lathe headstock typical of the mid-19th century. During the years intervening between the machines of figures 12 and 16, the general design was greatly improved by removing the lead screws from the center of the spindle. This made possible a shorter, much stiffer spindle and supported both ends of the spindle in one frame or headstock rather than in separate pieces attached to the bed. The screws were now mounted outside of the spindle-bearings, one at a time, while the mating nuts were cut partially into the circumference of a disk which could be turned to bring any particular nut into working position as required. With this arrangement, a wide variety of leads either right or left hand could be provided and additional leads could be fitted at any future time. Screw-cutting lathes of this design were popular for a very long time with instrument makers and opticians who had little need to cut screws of great length.

The demands of expanding industry for greater versatility in the production of engineering elements late in the 18th century set the stage for the evolution of more complex machines tending to place the threaded spindle lathes in eclipse. Maudslay's lathe of 1797-1800 (fig. 15) appeared at this time when industry was receptive to rapid innovation. Unfortunately, the gearing which once existed to connect the headstock spindle with the lead screw has long been lost. At this time it is quite difficult to say with certainty whether the original gear set offered a variety of ratios, as was true of slightly later Maudslay lathes, or a fixed ratio. The plausibility of the fixed ratio theory is supported by the very convenient means, seen in figure 15, for removing the lead screw in preparation for substitution of one of another pitch. All that is required is to back off its supporting center at the tailstock end and withdraw the screw from its split nut[2] and from the driving clutch near the headstock. This split nut also would have to be changed to one of a pitch corresponding to that of the screw. While more expensive than a solid nut, it neatly circumvents the need (and saves the time involved) to reverse the screw in order to get the tool back to the point of beginning preliminary to taking another cut. David Wilkinson's lathe of 1798 (fig. 17) which was developed in Rhode Island at the same time shows the same method of mounting and driving the master screw. At least in the United States, this method of changing the lead screw instead of using change gears remained popular for many years. Examples of this changeable screw feature are to be found in the lathes constructed for the pump factory of W. & B. Douglas Company, Middletown, Connecticut,[3] in the 1830's. Middletown, at that time one of the leading metal-working centers in one of the chief industrial States, had been for many years the site of the Simeon North arms factory which rivaled Whitney's. In this atmosphere, it is reasonable to expect that machinery constructed by local mechanics, as was the custom in those days, would reflect the most accepted refinements in machine design.

Roughly twenty years later, Joseph Nason of New York patented[4] the commercially very important "Fox" brassworker's lathe (fig. 18). While this does have a ratio in the pair of gears connecting the work spindle and master screw, it is clear from the patent that various pitches are to be obtained by changing screws, not by changing gears. The patent sums it up as follows:

A nut upon the end of the stud ... is unscrewed when the guide screw is to be removed or changed. The two wheels ... should have in their number of teeth a common multiple. They are seldom or never removed and their diameters are made dissimilar only for the purpose of giving to the guide screw a slower rate of motion than that of the mandrel whereby it may be made of coarser pitch than that of the screw to be cut and its wear materially lessened.

The introduction of gearing between the spindle and the lead screw, for whatever purpose, could not help but introduce variable factors caused by inaccuracies in the gears themselves and in their mounting. These were of little consequence for common work, particularly when coupled to a screw which, itself, was of questionable accuracy. The increasing refinements demanded in scientific instruments and in machine tools themselves after they had reached a relatively stable form dictated that attention be dedicated to improved accuracy of the threaded components.

An attack on this problem, which interestingly reverts to the fundamental principle of motion derived from a master screw without the intervention of other mechanism (fig. 19), is covered by a patent[5] issued to Charles Vander Woerd, one-time superintendent of the Waltham Watch Company. The problem is well stated in the patent:

This invention relates to the manufacture of leading screws to be used for purposes requiring the highest attainable degree of correctness in the cutting of the screw-threads of said screw ... as, for example, in machines for ruling lines in glass plates to produce refraction [sic] gratings for the resolution of the lines of the solar spectrum, such machines being required to rule many thousands of lines on an inch of space by a marking device which is reciprocated over the glass plate and is fed by the action of a leading screw after the formation of each line. Great difficulty has been experienced in constructing a leading screw for this and other purposes, in which the thread is so nearly correct as to produce no perceptible variation in the microscopic spaces between the ruled lines or gratings.... Various causes prevent the formation of a thread on the rod or blank, which is absolutely uniform and accurate from end to end of the rod. Among other causes are the variations of temperature from time to time, the imperfections of the operating leading screw, the springing of the leading screw and of the rod that is being threaded, and other unavoidable causes, all of which, although apparently trivial and producing only slight variations in the thread at different parts of the rod or blank, are of sufficient moment to be seriously considered when a screw of absolute accuracy is desired.

It is interesting to note in figure 19 that Vander Woerd's machine, to avoid the problems outlined in his patent, has returned to a starkly simple design. We are not told, however, how he originated this master screw which is used to produce the accurately threaded work pieces. Later generations, in the search for ever-greater accuracy, also returned to the fundamental simplicity of a master screw as we shall see when we consider the refinements in mechanism necessary to the extended development of the automobile and the airplane.

As the power and speed of automobiles and aircraft increased, critical parts became more highly stressed. Gears and threaded parts were particularly troublesome details of the mechanism because of the stresses concentrated in them, and, in the case of gears, because of the internal and external stresses originating in minute deviations from the ideal of tooth form and spacing. The problems were not entirely new but had hitherto been solved by increasing the size of the parts, an avenue of limited utility to designers in these fields where total weight as well as the effects of mass and inertia are so important. By making these parts of heat-treated steel, the strength could be made suitable while the size and mass of the parts were kept within bounds. The necessary processes of heat-treating were not always applicable to finished parts as they sometimes destroyed both finish and accuracy. Grinding, which was well developed for the simple plane, cylindrical, and conical surfaces so widely used in mechanisms, had to be extended to threads and gears so that they could be finished after heat-treating. Sometimes the gear teeth themselves were ground; for other applications it was sufficient to improve the accuracy of the gear cutters.

Attempts to produce gear hobs free of the imperfections and distortions introduced by heat treatment led to another return to the use of the master lead screw. Figure 20 illustrates a machine having this feature which was patented in 1932 by Carl G. Olson.[6] In speaking of the spindle-driving mechanism disclosed in earlier patents, the patent goes on to say:

This driving mechanism includes an integral spindle 20, one extremity thereof being designed for supporting a hob 22 and the other extremity thereof being formed so as to present a lead screw 24. The spindle 20 is mounted between a bearing 26 and a bearing 28, the latter bearing providing a nut in which the lead screw 24 rotates.... From the description thus far given it will be apparent that the rotation of the lead screw 24 within the bearing or nut 28 will cause the hob to be moved axially, the lead of the screw 24 being equal to the lead of the thread in the hob.

Claim 8 which concludes the descriptive portion of the patent states in part:

In a hob grinding machine of the class described, a rotary work supporting spindle, means for effecting longitudinal movement of the spindle, a tool holder for supporting a grinding wheel in operative position with respect to the work supported by the spindle during the rotary and longitudinal movement thereof, ...

Even before this patent was applied for, another patent was pending for the purpose of modifying the pitch of the lead screw without the use of change gears in spite of the wide acceptance of such gear mechanisms for over a hundred years.

Figure 21 shows a plan view[7] of the machine, and figure 22 a detailed view of the sine-bar mechanism actuated by the master screw, 6, to modify the effective pitch of the lead screw in accordance with the realities of practice as stated in the preamble of the patent:

This invention relates to material working machines, and particularly to machines such as hob grinders and the like, wherein the work is reciprocated through the agency of a lead screw.

In the manufacture of hobs it is common practice to employ the same machine for grinding hobs of varied diameters, and in order to employ such a machine in this manner the pitch of the lead screw, thereof, which actuates the work carrier, must conform to the axial pitch of the hob to be ground. This will be readily apparent when it is understood that the helix angles of hobs vary in accordance with their diameters and, consequently, the difference between the normal pitch and the axial pitch correspondingly varies. While the requirement for the normal pitch may be the same for hobs of different diameters, it is necessary to change the axial pitch in accordance with a change in the hob diameter, and this axial pitch of the hob is equal to the pitch of the lead screw which actuates the work carrier in grinding machines heretofore used. Hence, in order to adapt such machines to cover a wide range of leads, it is necessary to provide a large number of interchangeable lead screws and obviously this represents a large investment, and the interchanging of these screws requires the expenditure of considerable time in setting up the machine for each job.

Thread-grinding machines were being designed concurrent with the development of hob-grinding machines. Many were entirely concerned with features peculiar to the problems of wheel-dressing and to automatic characteristics. An invention to embody the use of a master screw and concerned with the precision grinding of worm threads, for use in gearing, was patented by Frederick A. Ward in this era.[8] That part of the invention pertaining to the use of a master screw, "a rotary work holder mounted on said carriage and provided with a driving spindle, an exchangeable master screw and stationary nut detachably secured to said spindle and head,..." is shown in figure 23.

Machines embodying the principle of the master lead screw are found in constant use by industry at the present time for specialized application. Whenever technological changes again reopen the topic of thread-cutting to a new degree of accuracy or call for a reevaluation of popular methods for any other reason, we may expect to see another resurgence of the master-screw method, for no other design eliminates so many variables or rests on such firm and fundamental natural principles as the machine of _Das mittelalterliche Hausbuch_ of 1483, the earliest such machine now known.

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FOOTNOTES

[1] JACQUES BESSON, _Des instruments mathématiques, et méchaniques, servants à l'intelligence de plusiers choses difficiles, & necessaires à toutes républiques_, 1st ed. (Orleans, 1569). [Also available in later editions in French, German, and Spanish.]

[2] J. FOSTER PETREE, introduction, _Henry Maudslay, 1771-1831, and Maudslay Sons and Field, Ltd._ (London: The Maudslay Society, 1949).

[3] _American Machinist_ (September 28, 1916), vol. 45, no. 13, pp. 529-531.

[4] U.S. patent 10383 issued to Joseph Nason of New York, January 3, 1854.

[5] U.S. patent 293930 issued to Charles Vander Woerd of Waltham, Massachusetts, February 19, 1884.

[6] U.S. patent 1874592, filed June 8, 1929, issued to C. G. Olson of Chicago, Illinois, August 30, 1932, and assigned to the Illinois Tool Works, also of Chicago.

[7] U.S. patent 1901926, filed February 16, 1928, issued to C. G. Olson of Chicago, Illinois, March 21, 1933, and assigned to the Illinois Tool Works, also of Chicago.

[8] U.S. patent 1899654, filed August 31, 1931, issued to F. A. Ward of Detroit, Michigan, February 28, 1933, and assigned to the Gear Grinding Company of Detroit, Michigan.

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Typographical Corrections

Page 107: "... servants à l'intelligence de plusieurs choses difficiles, & nécessaires ..." (had "a," "plusiers," "necessaires")

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CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY:

PAPER 38

THE EARLIEST ELECTROMAGNETIC INSTRUMENTS

_Robert A. Chipman_

ELECTROSTATIC INSTRUMENTS BEFORE 1800 123

INSTRUMENTING VOLTAIC OR GALVANIC ELECTRICITY, 1800-1820 124

ELECTRICAL INSTRUMENTATION, 1800-1820 125

OERSTED'S DISCOVERY 126

BEGINNINGS OF ELECTROMAGNETIC INSTRUMENTATION 126

CHRONOLOGY AND PRIORITY 127

ORIGINAL ELECTROMAGNETIC MULTIPLIERS 129

CONCLUSIONS 135

ACKNOWLEDGMENTS 136

_Robert A. Chipman_

THE EARLIEST ELECTROMAGNETIC INSTRUMENTS

_The history of the early stages of electromagnetic instrumentation is traced here through the men who devised the theories and constructed the instruments._

_Despite the many uses made of voltaic cells after Volta's announcement of his "pile" invention in 1800, two decades passed before Oersted discovered the magnetic effects of a voltaic circuit. As a result of this and within a five-month period, three men, apparently independently, announced the invention of the "first" electromagnetic instrument. This article details the merits of their claims to priority._

THE AUTHOR: _Robert A. Chipman is chairman of the Department of Electrical Engineering at the University of Toledo in Toledo, Ohio, and consultant to the Smithsonian Institution._

Electrostatic Instruments before 1800

It is the fundamental premise of instrument-science that a device for detecting or measuring a physical quantity can be based on any phenomenon associated with that physical quantity. Although the instrumentation of electrostatics in the 18th century, for example, relied mainly on the phenomena of attraction and repulsion and the ubiquitous sparks and other luminosities of frictional electricity, even the physiological sensation of electric shock was exploited semiquantitatively by Henry Cavendish in his well-known anticipation of Ohm's researches. Likewise, Volta in 1800[1] described at length how the application of his pile to suitably placed electrodes on the eyelids, on the tongue, or in the ear, caused stimulation of the senses of sight, taste and hearing; on the other hand, he reported that electrodes in the nose merely produced a "more or less painful" pricking feeling, with no impression of smell. The discharges from the Leyden jars of some of the bigger frictional machines, such as van Marum's at Leyden, were found by 1785 to magnetize pieces of iron and to melt long pieces of metal wire.[2]

The useful instruments that emerged from all of this experience were various deflecting "electrometers" and "electroscopes" (the words were not carefully distinguished in use), including the important goldleaf electroscope ascribed to Abraham Bennet in 1787.[3]

In 1786, Galvani first observed the twitching of the legs of a dissected frog produced by discharges of a nearby electrostatic machine, thereby revealing still another "effect" of electricity. He then discovered that certain arrangements of metals in contact with the frog nerves produced the same twitching, implying something electrical in the frog-metal situation as a whole. Although Galvani and his nephew Aldini drew from these experiments erroneous conclusions involving "animal electricity," which were disputed by Volta in his metal-contact theory, it is significant from the instrumentation point of view that the frog's legs were unquestionably by far the most sensitive detector of metal-contact electrical effects available at the time. Without their intervention the development of this entire subject-area, including the creation of chemical cells, might have been delayed many years. Volta himself realized that the crucial test between his theory and that of Galvani required confirming the existence of metal-contact electricity by some electrical but nonphysiological detector. He performed this test successfully with an electroscope, using the "condensing" technique he had invented more than a decade earlier.

Instrumenting Voltaic or Galvanic Electricity, 1800-1820

In his famous letter of March 20, 1800, written in French from Como, Italy, to the president of the Royal Society in London, Volta made the first public announcement of both his "pile" (the first English translator used the word "column"), and his "crown of cups" (the same translator used "chain of cups" for Volta's "couronne de tasses"). The former consisted of a vertical pile of circular disks, in which the sequence copper-zinc-pasteboard, was repeated 10 or 20 or even as many as 60 times, the pasteboard being moistened with salt water. The "crown of cups" could be most conveniently made with drinking glasses, said Volta, with separated inch-square plates of copper and zinc in salt water in each glass, the copper sheet in one glass being joined by some intermediate conductor and soldered joints to the zinc in the next glass.

Volta considered the "crown of cups" and the "pile" to be essentially identical, and as evidences of the electrical nature of the latter, said:

... if it contains about 20 of these stories or couples of metal, it will be capable not only of emitting signs of electricity by Cavallo's electrometer, assisted by a condenser, beyond 10° or 15°, and of charging this condenser by mere contact so as to make it emit a spark, etc., but of giving to the fingers with which its extremities (the bottom and top of the column) have been touched several small shocks, more or less frequent, according as the touching has been repeated. Each of these shocks has a perfect resemblance to that slight shock experienced from a Leyden flask weakly charged, or a battery still more weakly charged, or a torpedo in an exceedingly languishing state, which imitates still better the effects of my apparatus by the series of repeated shocks which it can continually communicate.[4]

The "effects" provided by Volta's pile and crown-of-cups are therefore electroscope deflection, sparks, and shocks. Later in the letter, he describes the stimulation of sight, taste, and hearing as noted earlier, but nowhere does he mention chemical phenomena of any kind, or the heating of a wire joining the terminals of either device. Hence, except for the additional physiological responses, he adds nothing to the catalog of observations on which instruments might be based. His familiarity with the moods of the torpedo (electric eel) seems to be intimate.

The reading of Volta's letter to the Royal Society on June 26, 1800, its publication in the Society's _Philosophical Transactions_ (in French) immediately thereafter, and its publication in English in the _Philosophical Magazine_ for September 1800,[5] gave scientists throughout Europe an easily constructed and continuously operating electric generator with which innumerable new physical, chemical, and physiological experiments could be made. Editor-engineer William Nicholson read Volta's letter before its publication and, by the end of April, he and surgeon Anthony Carlisle had built a voltaic pile. Applying a drop of water to improve the "connection" of a wire lying on a metal plate, they happened to notice gas bubbles forming on the wire, and pursued the observation to the point of identifying the electrical decomposition of water into hydrogen and oxygen.

Within two or three years innumerable electrochemical reactions had been described, some of which, one might think, could have served as operating principles for electrical instruments. Although the phenomena of gas formation and metal deposition were in fact widely used as crude indicators of the polarity and relative strength of voltaic piles and chemical cells during the period 1800-1820 (and the gas bubbles were made the basis of a telegraph receiver by S. T. Soemmering), the quantitative laws of electrolysis were not worked out by Faraday until after 1830, and not until 1834 was he satisfied that the electrolytic decomposition of water was sufficiently well understood to be made the basis for a useful measuring instrument. Describing his water-electrolysis device in that year, he wrote:

The instrument offers the only _actual measurer_ [italics his] of voltaic electricity which we at present possess. For without being at all affected by variations in time or intensity, or alterations in the current itself, of any kind, or from any cause, or even of intermissions of actions, it takes note with accuracy of the quantity of electricity which has passed through it, and reveals that quantity by inspection; I have therefore named it a VOLTAELECTROMETER.[6]

In passing, Faraday commented that the efforts by Gay-Lussac and Thenard to use chemical decomposition as a "measure of the electricity of the voltaic pile" in 1811 had been premature because the "principles and precautions" involved were not then known. He also noted that the details of _metal deposition_ in electrolysis were still not sufficiently understood to permit its use in an instrument.[7]

The heating of the wires in electric circuits must have been observed so early and so often with both electrostatic and voltaic apparatus, that no one has bothered to claim or trace priorities for this "effect." The production of incandescence, however, and the even more dramatic combustion or "explosion" of metal-foil strips and fine wires has a good deal of recorded history. Among the first to burn leaf metal with a voltaic pile was J. B. Tromsdorff of Erfurt who noted in 1801 the distinctly different colors of the flames produced by the various common metals. In the succeeding few years, Humphry Davy at the Royal Institution frequently, in his public lectures, showed wires glowing from electric current.

Early electrical instrumentation based on the heating effect took an unusual form. Shortly after 1800, W. H. Wollaston, an English M.D., learned a method for producing malleable platinum. He kept the process secret, and for several years enjoyed an extremely profitable monopoly in the sale of platinum crucibles, wire, and other objects. About 1810, he invented a technique for producing platinum wire as fine as a few millionths of an inch in diameter, that has since been known as "Wollaston wire." For several years preceding 1820, no other instrument could compare the "strengths" of two voltaic cells better than the test of the respective maximum lengths of this wire that they could heat to fusion. One can sympathize with Cumming's comment in 1821 about "the difficulty in soldering wires that are barely visible."[8]

Electrical Instrumentation, 1800-1820

The 20 years following the announcement of the voltaic-pile invention were years of intense experimental activity with this device. Many new chemical elements were discovered, beginnings were made on the electrochemical series of the elements, the electric arc and incandescent platinum wires suggested the possibilities of electric lighting, and various electrochemical observations gave promise of other practical applications such as metal-refining, electroplating, and quantity production of certain gases. Investigators were keenly aware that all of the available means for measuring and comparing the _electrical_ aspects of their experiments (however vaguely these "electrical aspects" may have been conceived), were slow, awkward, imprecise, and unreliable.

The atmosphere was such that prominent scientists everywhere were ready to pounce immediately on any reported discovery of a new electrical "effect," to explore its potentialities for instrumental purposes. Into this receptive environment came H. C. Oersted's announcement of the magnetic effects of a voltaic circuit, on July 21, 1820.[9]

Oersted's Discovery

Many writers have expressed surprise that with all the use made of voltaic cells after 1800, including the enormous cells that produced the electric arc and vaporized wires, no one for 20 years happened to see a deflection of any of the inevitable nearby compass needles, which were a basic component of the scientific apparatus kept by any experimenter at this time. Yet so it happened. The surprise is still greater when one realizes that many of the contemporary natural philosophers were firmly persuaded, even in the absence of positive evidence, that there _must_ be a connection between electricity and magnetism. Oersted himself held this latter opinion, and had been seeking electromagnetic relationships more or less deliberately for several years before he made his decisive observations.

His familiarity with the subject was such that he fully appreciated the immense importance of his discovery. This accounts for his employing a rather uncommon method of publication. Instead of submitting a letter to a scientific society or a report to the editor of a journal, he had privately printed a four-page pamphlet describing his results. This, he forwarded simultaneously to the learned societies and outstanding scientists all over Europe. Written in Latin, the paper was published in various journals in English, French, German, Italian and Danish during the next few weeks.[10]

In summary, he reported that a compass needle experienced deviations when placed near a wire connecting the terminals of a voltaic battery. He described fully how the direction and magnitude of the needle deflections varied with the relative position of the wire, and the polarity of the battery, and stated "From the preceding facts, we may likewise collect that this conflict performs circles...." Oersted's comment that the voltaic apparatus used should "be strong enough to heat a metallic wire red hot" does not excuse the 20-year delay of the discovery.

Beginnings of Electromagnetic Instrumentation

The mere locating of a compass needle above or below a suitably oriented portion of a voltaic circuit created an electrical instrument, the moment Oersted's "effect" became known, and it was to this basic juxtaposition that Ampère quickly gave the name of galvanometer.[11] It cannot be said that the scientists of the day agreed that this instrument detected or measured "electric current," however. Volta himself had referred to the "current" in his original circuits, and Ampère used the word freely and confidently in his electrodynamic researches of 1820-1822, but Oersted did not use it first and many of the German physicists who followed up his work avoided it for several years. As late as 1832, Faraday could make only the rather noncommittal statement: "By current I mean anything progressive, whether it be a fluid of electricity or vibrations or generally progressive forces."[12]

Nevertheless, whatever the words or concepts they used, experimenters agreed that Oersted's apparatus provided a method of monitoring the "strength" of a voltaic circuit and a means of comparing, for example, one voltaic battery or circuit with another.

It was perfectly clear, from Oersted's pamphlet, that if a compass needle was deflected clockwise when the wire of a particular voltaic circuit lay above it in the magnetic meridian, the same needle would _also_ be deflected clockwise if the wire was turned end-for-end and placed _below_ the compass needle, without changing the rest of the circuit. Anyone perceiving this fact might deduce, as a matter of logic, that if the wire of the circuit was first passed above the needle, in the magnetic meridian, then folded and returned in a parallel path below the needle, the deflecting effect on the needle would be repeated, and a more sensitive indicator would result, assuming that any additional wire introduced has not affected the "circuit" excessively.

Since 1821, historical accounts of the origins of electromagnetism seem to have limited their credit assignments for the conception and observation of this electromagnetic "doubling" effect (or "multiplying" effect, if the folding is repeated) to three persons. Almost without exception, however, these accounts have given no specific information as to precisely what each of these three accomplished, what physical form their respective creations took, what experiments they performed, and what functional understanding they apparently had of the situation. The usual statement is simply that a compass needle was placed in a coil of wire.[13] The main purpose of the present review is to recount some of these details.

The following are the three candidates whose names are variously associated with the "invention" of the first constructed electromagnetic instrument, or "multiplier," or primitive galvanometer.

JOHANN SALOMO CHRISTOPH SCHWEIGGER (1779-1857) in 1820 had already been editor for several years of the _Journal für Chemie und Physik_, and was professor of chemistry at the University of Halle.

JOHANN CHRISTIAN POGGENDORF (1796-1877) in 1820 had only recently entered the University of Berlin as a student following several years as an apothecary's apprentice and a brief period as an apothecary. Four years later, he succeeded Gilbert as editor of the influential _Annalen der Physik_, a position he held for more than 50 years.

JAMES CUMMING (1771-1861) in 1820 was professor of chemistry at Cambridge University.

Chronology and Priority

The earliest established date in the "multiplier" record is September 16, 1820, when Schweigger read his first paper to the Natural Philosophy Society of Halle. There seems to be no reason to doubt that this report justifies the frequently used label "Schweigger's multiplier."

In an exuberant support of Schweigger's position, Speter[14] with no mention of Cumming and no hint of "invention" details, shows that Poggendorf in 1821 admitted Schweigger's priority, but suffered some lapse of memory 40 years later when writing sections of his biographical dictionary, leaving a distinct suggestion that the invention was his. Further confusion for later generations resulted from some ambiguous entries in the _Allgemeine Deutsche Biographie_ of 1888. The name "multiplier" seems not to have originated with Schweigger himself. Speter credits it to Meineke as "working" editor of Schweigger's _Journal_, but Seebeck seems to have used it much earlier.[15]

Conceding priority of conception to Schweigger (Cumming has not been a real competitor on this point) does not alter the fact that all three seem to have reached their results independently of one another, that the first work of each on this subject was published within a period of five months, that there were significant differences in their conceptions of the uses and the optimum design of their devices and that between them they provided an adequate foundation for the subsequent development of the galvanometer to become the primary electrical-measuring instrument.

In the matter of publication, Schweigger, as editor of what was popularly called Schweigger's _Journal_, had an obvious advantage, and presented his experiments beginnings on page 1 of the first volume of his _Journal_ for 1821, published January 1 of that year.[16] Oersted's paper had appeared two volumes previously. He began by referring to Oersted's discovery as "the most interesting to be presented in a thousand years of the history of magnetism." He was, in fact, so impressed with the epochal nature of Oersted's achievement that he commemorated it by giving his _Journal_ a second title so that "volume one" of the new title could begin in the year after Oersted's publication.

Poggendorf, as a relatively junior student, had no such easy access to publicity, but he had a staunch admirer in one of his professors, Paul Erman at the University of Berlin. Erman added a seven-page postscript on Poggendorf's invention to his book _Outline of the Physical Aspects of the Electro-chemical Magnetism Discovered by Professor Oersted_, published before April 1821,[17] with an introductory paragraph:

Herr Poggendorf, who is one of the most excellent ornaments of the lecture room and laboratory of the University here, carried out a very coherent and well-conceived investigation of electro-chemical magnetism, leading step-by-step to a method of amplifying this activity-phenomenon by means of itself.

The postscript begins by referring to the "condenser [_Kondensator_] just brought to my attention by Herr Poggendorf" and explains that he cannot release his treatise "without preliminary announcement of this subject of the highest importance." (It can be inferred from the text that the name "condenser" was chosen because of the device's enhancing of magnetic measurements analogously to the enhancing of electric measurements by Volta's electrostatic "condenser.")

Immediately on reading the book, Schweigger published extracts, mainly of the postscript, with indignant comments on Erman's remissness (or worse) in having failed to mention Schweigger's prior work.[18]

However, Erman was not alone in his unawareness, if it was that, of Schweigger's discovery.

Rival editor Gilbert of the _Annalen der Physik_ reviewed Erman at much greater length than Schweigger, reprinting most of the postscript with evident enthusiasm, and stating in his preamble that the invention is attributed to "a young physicist studying here in Berlin, Herr Poggendorf."[19] Only in a footnote is the reader directed to another footnote in the next article in the volume, where Gilbert finally states that he "cannot leave unmentioned the fact that this amplifying apparatus seems to be due to Herr Professor Schweigger." He then quotes rather fully from Schweigger's first two papers.[16] Oersted in 1823 explained the situation thus: "The work of M. Poggendorf, having been mentioned in a book on electromagnetism by the celebrated M. Erman published very shortly after its discovery, became known to many scientists before that of M. Schweigger. This is the reason for the same apparatus carrying different names."[20]

The same confusion is well illustrated by the paper to which Gilbert attached his confessional footnote mentioned above. Written by Professor Raschig of Dresden, on April 3, 1821, the paper is entitled "Experiments with the Electro-magnetic Multiplier," but the device, throughout the paper, is repeatedly referred to in the phrase "Poggendorf's condenser, or rather multiplier," an awkward combination that suggests editorial intervention.[21]

The work of James Cumming at Cambridge is described in two papers which he read to the Cambridge Philosophical Society in 1821, which were then duly published in the _Transactions_ of that Society. The first, "On the Connexion of Galvanism and Magnetism," was read April 2, 1821,[22] and the second, "On the Application of Magnetism as a Measure of Electricity," was read a few weeks later on May 21st.[23]

Though he quotes some unrelated 18th-century experiments by Ritter in Germany, an 1807 publication of Oersted's, and electromagnetic experiments with solenoids performed by Arago and Ampère in late 1820, Cumming makes no mention of Schweigger or Poggendorf, and never uses the word "multiplier." It, therefore, seems probable that his work was done without knowledge of the German publications or inventions.

Original Electromagnetic Multipliers

Of the three sets of instruments made, respectively, by Schweigger, Poggendorf and Cumming, those of Schweigger are the most elementary, and the least realistic from a practical point of view. He makes little effort to investigate the effect of any design parameters, but presents some odd conductor configurations that involve unimportant variations of the basic principle. The following extracts from his first three papers[13] contain the major references to his conception, construction, and use of his multiplier.

PAPER READ IN HALLE, SEPTEMBER 16, 1820

That a powerful voltaic pile is required for these experiments (of Oersted) I have confirmed in my physics lectures, using an electric pile that was so strong it would easily produce potassium metal the second and third day after it was built. However, I soon saw that the electromagnetic effect was related, not to the pile, but to the simple circuit, and I was thereby led to perform the experiment with much greater sensitivity. To amplify these electromagnetic phenomena of the simple circuit it seemed to me necessary to adopt a different arrangement from that initiated by Volta, in order that the electrical phenomena of his simple circuit might be raised to a higher degree.

Since a reversal of the effect occurs according to whether the connecting-wire lies over or under the needle, and likewise according to whether the wire leads from the positive or negative pole, thence I say it is an easy inference that a doubling of the effect is attainable, which is verified in practice.

I present to the Society the simple "doubling apparatus" [_Verdoppelungs-Apparat_], where the compass is placed between two wires passing around it. A multiplication of the effect is easily obtained when the wire is not just once but many times wound around. A single turn suffices, however, to demonstrate Oersted's experiments, using small strips of zinc and copper dipped in ammonium-chloride solution.

Amid innumerable, rambling theorizations (such as, that "hydrogenation affects magnetism as oxidation affects galvanism," or "sulphur, phosphorous and carbon are especially significant in magnetism, since iron in combination with any of these inflammable materials becomes a magnet-material"), Schweigger announces that he looked for the reactive force of the needle on the connecting wire in the simple Oersted experiment, and that he used his "amplifying apparatus" to look for magnetic effects from an electrostatic machine, but without success in both cases. He suggests that he will continue with many more electromagnetic experiments because "with the use of the doubling-apparatus, the needle, instead of needing for excitation a cell capable of generating sparks, approaches more closely the sensitivity of a twitching nerve." However, "additional special experiments are required to find to what limits the amplification can be increased by the method I have created in the construction of this doubling-apparatus, using multiple turns of wire."

PAPER READ IN HALLE, NOVEMBER 4, 1820

[The first half of this paper describes successful observations of the reaction-force of a magnetic needle on the connecting wire of a voltaic circuit, achieved by pivoting the connecting wire in the form of brass needles above and below the compass needle. Though the multiplier configuration of needle and wire is in fact present here, Schweigger does not mention it, evidently regarding this as a separate project. He continues.]

In my lecture of September 16th, I showed that Oersted's results depend, not on the voltaic cell, but only on the connecting circuit. The principle I have used for amplification of the effects, for the construction of an electromagnetic battery as it were, was the winding of wire around the compass, and I now present to the Society a bow-pattern of multiple-wound, wax-insulated wire, Figure 3. [There were no illustrations with Schweigger's first paper.] While a single wire, using the weak electric circuit here, deflects the magnetic needle only 30° or 40°, if the compass is placed in one of the openings of this pattern, the needle is deflected 90° to the east, or in the other opening 90° to the west, using the same weak electric circuit....

The "bow-pattern" device has novelty interest only, adding nothing to the elucidation of the multiplier phenomenon. The same is true of Schweigger's next proposal, shown in figure 4. "... I will now add another apparatus, which is just an extension of the previous one, whereby the needle can take up any angle from 0° to 180°." A short length of circular glass tubing, of inside diameter large enough to contain a compass needle, stands with its axis vertical and has single or multiple loops of wire wound on it in vertical diametral planes. In the illustration, successive plane coils are inclined at 30° to one another. "... the electric current flows through the whole wire, and the needle moves under all of these currents, and coming always into another loop can take any desired angle."

With much further theorizing about "the correlation of magnetism with the cohesion of bodies," Schweigger states again his evaluation of his discovery: "Oersted succeeded in electromagnetic research by using a spark-producing cell, which could make a wire glow. My amplifying electromagnetic device needs only a weak circuit of copper, zinc, and ammonium chloride solution."[24]

"FURTHER WORDS ABOUT THE NEW MAGNETIC PHENOMENA"

[This was presumably written between November 4, 1820, and the January 1, 1821, publication date of his _Journal_.]

These wonderful new electrical effects[25] are most easily rendered perceptible with the help of the previously described wire loops. To focus attention on just one of the windings of Figure 3, we sketch a new drawing, Figure 5.... Since it is of major importance that these loops be made of silk-covered wire lying evenly on one another, it is convenient to wind the loops on two small slotted sticks of wood, although it is also possible to hold the wires together with wax or shellac, or to tie them together in an orderly manner with silk thread....

In Figure 5, Aa and Cc represent little slotted rods of wood on which the silk-covered wire is wound. Only three windings are shown in the figure, but I generally adopt three times that many. Now t is connected with the copper and d with the zinc, and the compass B set between the rods Aa and Cc with the coil perpendicular to the magnetic meridian and the terminals d, t at the east.

The instant Z and K are dipped in the ammonium chloride solution, the needle turns around and stays with the north pole point south....

If now the compass is taken out of the coil and put in position b, all effects are reversed, and are considerably weaker, for obvious reasons....

It is of the same significance whether we bring the compass from B to b in Figure 5, or from mesh 1 to mesh 2 in Figure 3, only that in the latter case, because the compass is enclosed by the two sides, a stronger effect results....

If now the coil is rotated ... so that the face previously north now faces south, then on connecting the electric circuit there is absolutely no trace of effect on the needle, assuming that the terminal wires are not reversed....

It seems unnecessary to note that our magnetic coil can be placed in the direction of the magnetic meridian or at any arbitrary angle with it....

Following several pages of further talk about the relation of "cohesion to magnetism" and about "unipolar and bipolar conductors," the only additional item of interest is the observation that discharges of a Leyden jar (_Kleistichen Flasche_) strong enough to burn strips of leaf gold and to magnetize an iron rod in a coil, produced no compass-needle deflections, even with the help of the "amplifying apparatus."

Schweigger, therefore, described the basic multiplier idea clearly enough in his first paper, but offered no sketch of the simplest construction until the third paper. In the second paper, meanwhile, he had illustrated two peculiar designs involving the principle in less elementary ways.

His indifference to whether the wire loops lie _in_ the magnetic meridian (fig. 3) or perpendicular to it (fig. 5) or "at any other arbitrary angle to it," reveals a poor appreciation of the measuring-instrument potentialities. His conception seems to be primarily that of a detector.

Poggendorf's invention, as first reported by Erman and presented to a wider audience by Gilbert[26] was described as consisting of typically 40 to 50 turns of 1/10-line diameter, silk-covered copper wire tied tightly together, with the whole pressed laterally to form an elliptical opening in which a pivoted compass needle could move freely while maintaining clearance of about 2 lines from the wire at all points.[27]

"This magnetic condenser can be a great boon to electro-chemistry," said Erman, for "it avoids all the difficulties of electric condensers." He noted that, using the condenser, Poggendorf had already established the electric series for a great number of bodies, discovered various anomalies about conductivities, and found a way of detecting dissymmetry of the poles of a compass needle. On the other hand, even with the condenser, no magnetic effects have so far been obtainable from a strong tourmaline, or from a 12,000-pair, Zamboni dry cell.

Poggendorf's own account of his work finally appeared as a very long article in the journal known as "Oken's Isis."[28] The editorial controversies mentioned earlier may have occasioned this use of a periodical of such minor status in the fields of physics and chemistry.

The source of Poggendorf's vision of the multiplier principle was a little different from Schweigger's inspiration. Aiming at some detailed analysis of Oersted's observation, Poggendorf ran the connecting wire of his cell-circuit along a vertical line to just above or below the pivot-point of the compass needle, then, after a right-angle bend, horizontally above or below one of the poles of the needle. As he studied the deflections produced for all four possible positions of such a wire, with both cell polarities, he came to realize that if a rectangular wire loop in a vertical plane enclosed a compass needle, all parts of the horizontal sides of the loop would produce additive deflections. By a separate experiment, he showed that the vertical sides of the loop would also increase the deflections. He saw at the same time that the effect of additional turns would be cumulative.

The multiple surrounding of the needle by a silk-covered wire, in a plane perpendicular to the long axis of the needle, affords the physicist a very simple and sensitive means of detecting the slightest trace of galvanism, or of magnetism produced by it, so that I have given the name of magnetic condenser to this construction, though I attach no special value to this name ...

In analyzing the astonishingly increased power which the condenser gives to the magnetic effect of a circuit, the first question that arises is how the effect varies with the number of turns, whether it increases indefinitely or reaches a maximum beyond which additional turns have no effect. The answer to this first question is linked to the solution of another, viz, whether the degrees deflection are a direct expression of the measure of the magnetic force or not.

To instruct myself on this point I made use of three separate circuits, each containing an 8-turn condenser, and put these as close together as possible in the magnetic meridian ... with the needle between the windings. Each single circuit ... gave a deflection of 45° ... When two were connected the deflection was 60°, and when finally all three were put in magnetic operation, the deflection grew to only 70°. It appears clearly from this that the angle of deflection is not in a simple ratio with the magnetic force acting on the needle....

Neither Poggendorf nor Schweigger seems to have ruled out, on logical grounds alone, the possibility of deflections greater than 90°, with the loop-plane in the magnetic meridian, though Poggendorf does add a vague note that if the needle deflected too far it would encounter forces of the opposing sign.

Poggendorf experimented with the size of the circuit wires, finding that larger wires led to greater deflections. He noted that the size of the cell plates and the nature of the cell's moist conductors would certainly have a great effect, but that to investigate these in detail would take undue time, and he therefore proposed to keep this part of the apparatus constant, using one pair of zinc and copper plates 3.6 inches in diameter, separated by cloth soaked in ammonium-chloride solution.

Poggendorf's principal quantitative study of his magnetic condenser used 13 identical coils, each with 100 turns. In order that the turns should all be at approximately the same distance from the needle, the coils were wound of the finest brass wire that could be silk-insulated, the wire diameter being 0.02 lines. On adding coils one at a time across the cell (i.e., connecting them in parallel), the deflections were as follows:

Turns 100 200 300 400 500 600 700 Deflection in degrees 45 50 55 59-60 62 63 64

Turns 800 900 1000 1100 1200 1300 Deflection in degrees 65 65-1/2 66 66 66 66

Adding some coils with fewer turns, and connecting various combinations "as a _continuum_" (i.e., in series), the deflections using the same cell were:

Turns 1 5 10 25 50 75 100 200 Deflection in degrees 10 22 27 30 35-40 40 40 40

Turns 300 400 500 600 700 800 900 1000 Deflection in degrees 40 40 41 40 40 40 40 40

Making a few coils from wire with 1/8-line diameter, the deflections, again using the same cell were:

Turns 5 25 50 100 Over 100 Deflection in degrees 20-22 40-45 45 65 65

Since the needle used in these experiments was almost as long as the inside clearance of the coils, no simple tangent law can be applied, and it is not possible to discover an equivalent circuit in modern terms. However, the constancy of the deflections for large numbers of turns in each case indicates that the cell voltage and resistance were fairly constant, and a rough estimate suggests that the cell resistance was comparable to the resistance of one of the 100-turn coils of fine wire. Such a value means that cell resistance limited the maximum deflections for the parallel-connected multipliers, while coil resistance fixed the limit in the series case.

For all of these reasons, it was impossible that any useful functional law could be obtained from the data.

Poggendorf concluded only that "the amplifying power of the condenser does not increase without limit, but has a maximum value dependent on the conditions of plate area and wire size." He added two other significant comments derived from various observations, that the basic Oersted phenomenon is independent of the earth's magnetism, and that the phenomenon is localized, i.e., is not affected by distant parts of the circuit.

Only a small fraction of Poggendorf's paper is devoted to elucidating the properties of the condenser. A similar amount is concerned with refuting various proposals, such as those of Berzelius and Erman, about distributions of magnetic polarity in a conducting wire to account for Oersted's results. More than half of the paper describes results obtained by using the condenser to compare conductivities and cell polarities under conditions where no effect had previously been detectable. Notable is the observation of needle deflections in circuits whose connecting wires are interrupted by pieces of graphite, manganese dioxide, various sulphur compounds, etc., materials which had previously been considered as insulators in galvanic circuits. Poggendorf gives these the name of "semi-conductor" (_halb-Leiter_).

Cumming's first mention of the multiplier phenomenon, in his paper of April 2, 1821,[22] is quite casual, and describes only a one-turn construction. He speaks first of single-turn ring of thick, brass wire, and after noting that the sides of a circuit produce additive effects on a needle, he comments that a flattened rectangular loop produces nearly quadruple the effect of a single wire. The paper is primarily a review of Oersted's work, with references to electromagnetic observations before Oersted, and accounts of various related but nonmultiplier experiments that Cumming has made. His second paper, of May 21st, contains a fine plate (fig. 6) illustrating arrangements used in investigating the subject of the paper's title "The Application of Magnetism as a Measure of Electricity." (Neither Poggendorf nor any of his commentators ever illustrated his "condenser.")

Although this plate is never referred to in the paper itself, a nearby "Description" gives a few comments. The two wire patterns shown are noted as simply "forms of spiral for increasing the electromagnetic intensity." The mounted wire loop, with enclosed compass needle and terminal mercury cups, is clearly identical in principle with the devices of Schweigger and Poggendorf, and is called a "galvanoscope." The largest structure illustrated does not involve the multiplying effect. It is called a "galvanometer," consistent with Ampère's definition of that word. To use it, two leads of a voltaic circuit are inserted into the mercury cups AC and BD, and the board EFGH carrying the cups is moved vertically until some "standard" deflection is obtained on the compass needle below. The relative "strength" of the circuit is then given by the calibrated position of the sliding section. Uncertainties are undoubtedly introduced by the arbitrary positions of the connecting wires from the test circuit to the mercury cups, but Cumming drew some interesting conclusions from various measurements he made.

Observing needle deflections for various positions of the wire A-B, with a "constant" voltaic circuit, he found that "the tangent of the deviation varies inversely as the distance of the connecting wire from the magnetic needle." Here is a combination of the deflection law for a needle in a transverse horizontal field and the magnetic-force law for a long, straight wire. The latter had been determined experimentally by Biot and Savart, in November 1820, by timing the oscillations of a suspended magnet.[29]

Cumming considers his straight-wire calibrated "galvanometer" to be a device for "measuring" galvanic electricity; on the other hand, his multiple-loop "galvanoscopes" are for "discovering" galvanic electricity. With the multiplier instrument, he found galvanic effects (i.e., needle deflections) using copper and zinc electrodes with several acids not previously known to create galvanic action. A potassium-mercury amalgam electrode created a powerful cell with zinc as the positive electrode, establishing both the metallic nature of potassium and the fact that it is the most negative of all metals.

In a third paper, presented April 28, 1823,[30] Cumming reports use of the galvanoscope in experiments on the thermoelectric phenomena recently discovered by Seebeck. His note that "for the more minute effects a compass was employed in the galvanoscope, having its terrestrial magnetism neutralized ..." seems to be the earliest mention of this version of the astatic principle, a technique whose dramatic effects were especially valuable in low-resistance thermoelectric circuits, where the extra resistance of additional multiplier turns largely offsets their magnetic contribution. In detail, "the needle is neutralized by placing a powerful magnet North and South on a line with its center; and another, which is much weaker, East and West at some distance above it: by means of the first the needle is placed nearly at right angles to the meridian, and the adjustment is completed by the second."

On varying the length of the connecting wire of the circuit, Cumming found the deflections of the multiplier needle to be in a nearly reciprocal relation. He speaks of the "conducting power of the wire," and seems not far from visualizing Ohm's law, of which no published form appeared until 1826. Ohm's own experiments were made with very similar apparatus.

Conclusions

An effort has been made to show that electrical experimenters prior to Oersted's discovery in 1820 were in desperate need of some electrical instrument for galvanic or voltaic circuits that would combine sensitivity, simplicity, reliability, and quick response. The nearly simultaneous creation by Schweigger, Poggendorf and Cumming of an arrangement consisting of a coil of wire and a compass needle provided the first primitive version of a device to fill that need.

It appears that Schweigger is clearly entitled to credit for absolute priority in the discovery, but the original sources suggest that both his understanding of the device and the subsequent researches he performed with it were markedly inferior to those of the other independent discoverers. In using the generic label, "Schweigger's Multiplier," there have been historical examples of attributing to Schweigger considerably more sophistication than is justified. Figure 7 shows an instrument designed by Oersted in 1823,[20] which he says "differs in only minor particulars from that of M. Schweigger." On comparing figure 7 with figures 3, 4, or 5, the remark seems overly generous.

The history of the multiplier instruments has had its fair share of erroneous reports and misleading clues. A fine example is the illustration of figure 8, taken from what is often quoted as the first report in English on Poggendorf's "Galvano-Magnetic Condenser."[31] The sketch is the editor's interpretation of a verbal description given him by a visiting Danish chemist who, in turn, had received the information in a letter from Oersted. It incorporates, faithful to the description, a "spiral wire ... established vertically," with a needle "in the axis of the spiral," yet by misunderstanding of the axial relations and of the ratio of length to diameter for the coil, a completely meaningless arrangement has resulted. The confusion is compounded by the specifying of an _unmagnetized_ needle.

Schweigger and Poggendorf, through their editorial positions, were among the best known of all European scientists for several decades. On one basis or another their reputations are firmly established. Comparison of the accounts of the early "multipliers," however, suggests that the Reverend James Cumming, professor of chemistry at the University of Cambridge, was a very perceptive philosopher. This was well understood by G. T. Bettany who wrote in the _Dictionary of National Biography_ that Cumming's early papers "though extremely unpretentious," were "landmarks in electromagnetism and thermoelectricity," and concluded that: "Had he been more ambitious and of less uncertain health, his clearness and grasp and his great aptitude for research might have carried him into the front rank of discoverers."

ACKNOWLEDGMENTS

I wish to thank Dr. Robert P. Multhauf, chairman of the Department of Science and Technology in the Smithsonian Institution's Museum of History and Technology, for encouragement in the writing of this paper and for the provision of opportunity to consult the appropriate sources. To Dr. W. James King of the American Institute of Physics, I am grateful for many provocative discussions on this and related topics.

* * * * *

FOOTNOTES

[1] A. VOLTA, "On the Electricity Excited by the Mere Contact of Conducting Substances of Different Kinds," _Philosophical Transactions of the Royal Society of London_ (1800), vol. 90, pp. 403-431.

[2] Some little-known but delightful observations in the prehistory of electromagnetism are described in a letter written by G. W. SCHILLING from London to the Berlin Academy on July 8, 1769, published as "Sur les phénomènes de l'Anguleil Tremblante" [_Nouveaux Mémoires de l'Académie Royale des Sciences et Belles-Lettres_, 1770 (Berlin, 1772), pp. 68-74], translated to French from the original German. The letter recounts a multitude of experiments with various electric eels. The two observations of electromagnetic interest are that a piece of iron held by the hand in the eel's tank could be felt quivering even when the fish was stationary several inches away, and a compass needle showed a deflection, both in the water near the fish, and outside the tank, also with the fish stationary.

[3] ABRAHAM BENNET, _Philosophical Transactions of the Royal Society of London_ (1787), p. 26.

[4] Op. cit. (footnote 1), p. 403.

[5] _Philosophical Magazine_ (1800), vol. 7, pp. 289-311. [For a facsimile reprint, see _Galvani-Volta_ (Bern Dibner's Burndy Library Publication No. 7), Norwalk, Connecticut, 1952.]

[6] MICHAEL FARADAY, _Experimental Researches in Electricity_, vol. 1 (London, 1839), paragraph 739, dated January 1834.

[7] Ibid., sec. 741.

[8] JAMES CUMMING, "On the Application of Magnetism as a Measure of Electricity," _Transactions of the Cambridge Philosophical Society_ (1821), vol. 1, pp. 282-286. [Also published in _Philosophical Magazine_ (1822), vol. 60, pp. 253-257.]

[9] H. C. OERSTED, _Experimenta Circa Effectum Conflictus Electrici in Acum Magneticam_ (Copenhagen, July 21, 1820).

[10] Full details of Oersted's work and publications are in _Oersted and the Discovery of Electromagnetism_ (Bern Dibner's Burndy Library Publication No. 18), Norwalk, Connecticut, 1961. The original Latin version and first English translation are reproduced in _Isis_ (1928), vol. 34, pp. 435-444.

[11] A. M. AMPÈRE, _Annales de Chimie et de Physique_ (1820), vol. 15, p. 67. The word "galvanometer" had been used much earlier by BISCHOF, "On Galvanism and its Medical Applications," _The Medical and Physical Journal_ (1802), vol 7, p. 529, for a form of goldleaf electroscope shown here in figure 2, but this use of the word does not seem to have been adopted by others.

[12] Op. cit. (footnote 6), paragraph 283, dated January 1833. A similar attitude was expressed in the same year by CHRISTIE, _Philosophical Transactions of the Royal Society of London_ (1833), vol. 123, p. 96: "I adopt the word current as a convenient mode of expression, ... but I would not be considered as adopting any theoretical views on the subject...."

[13] Some prominent examples of this brevity of treatment are in E. HOPPE, _Geschichte der Elektrizität_ (Leipzig, 1884); O. MAHR, _Geschichtliche Einzeldarstellungen aus der Elektrotechnik_ (Berlin, 1941); R. S. WHIPPLE, "The Evolution of the Galvonometer," _Journal of Scientific Instruments_ (1934), vol. 7, pp. 37-43; WILLIAM STURGEON, _Scientific Researches_ (Bury, 1850); A. W. HUMPHREYS, "The Development of the Conception and Measurement of Electric Current," _Annals of Science_ (1937), vol. 2, pp. 164-178.

[14] M. SPETER, "Klärung der Multiplikator-Prioritätsfrage Schweigger-Poggendorf," _Zeitschrift für Instrumentenkunde_ (1937) vol. 57, pp. 29-32.

[15] T. SEEBECK, "Über den Magnetismus der Galvanischen Kette," _Abhandlungen der Koenigliche Akademie der Wissenschaften zu Berlin_ (1820-1821), pp. 289-346. The phrase "Schweigger's multiplier" is used on page 319. The many experiments described in this paper added little or nothing to contemporary appreciation of the multiplier as an instrument.

[16] J. S. C. SCHWEIGGER, _Journal für Chemie und Physik_ (1821), vol. 31, pp. 1-18, 35-42. Pages 1-6 are the paper presented in Halle on September 16, 1820; pages 7-18 are the paper presented in Halle on November 4, 1820, and pages 35-42 are "a few additional words." The preface to the whole volume is dated January 1, 1821. A somewhat earlier public announcement referring to Schweigger's discovery appeared in the _Allgemeine Literatur-Zeitung_ (November 1820), no. 296, cols. 622-624, but this was lacking in detail and seems not to have been noticed by any scientists.

[17] P. ERMAN, _Umrisse zu den physischen Verhältnissen des von Herrn Prof. Oersted entdeckten elektro-chemischen Magnetismus_ (Berlin, 1821). Hoppe (footnote 13) states that Erman's book was published in May; however, it is referred to in a letter dated April 3, 1821, by RASCHIG, _Annalen der Physik_ (1821), vol. 67, pp. 427-436.

[18] Op. cit. (footnote 16), vol. 32, pp. 38-50.

[19] _Annalen der Physik_ (1821), vol. 67, pp. 382-426, and footnote on pages 429-430 of same volume. The footnote accompanies the article by Raschig mentioned in footnote 17.

[20] H. C. OERSTED, "Sur le Multiplier electro-magnetique de M. Schweigger, et sur quelques applications qu'on en a faites," _Annales de Chimie et de Physique_ (1823), vol. 22, pp. 358-365.

[21] "Versuche mit dem electrisch-magnetischen Multiplicator," _Annalen der Physik_ (1821), vol. 67, pp. 427-436.

[22] _Transactions of the Cambridge Philosophical Society_ (1821), vol. 1, pp. 269-278.

[23] Op. cit. (footnote 8).

[24] The German word _Kette_ has been translated as "circuit" throughout. Although the equivalence of these words is clear, for example, in Ohm's work of 1826, the context in which _Kette_ is sometimes used in 1820 and 1821 indicates that the concept of a "circuit," in the sense of the wiring external to the source of electricity, has not been established. The wiring is regarded more as something incidental, used to "close" the cell, the cell being considered essentially the whole of the apparatus. This view underlies the many attempts to correlate the Oersted phenomena with cell materials and design, and with the use of such terms as "chemical magnetism" by Erman and others.

[25] The reference here is to the Oersted-type experiments described in two papers by authors other than Schweigger on pages 19 to 34 of the volume.

[26] Op. cit. (footnote 19), pp. 422-426.

[27] One "line" seems to have been about 1/12 inch.

[28] J. G. POGGENDORF, "Physisch-chemische Untersuchungen zur näheren Kenntniss des Magnetismus der voltaischen Säule," _Isis von Oken_ (1821), vol. 8, pp. 687-710. Most of Poggendorf's numerical data is also in C. H. PFAFF, _Der Elektromagnetismus_ (Hamburg, 1824), along with some of Pfaff's own work.

[29] Reported in _Annales de Chimie et de Physique_ (1820), vol. 15, pp. 222-223.

[30] "On the Development of Electro-Magnetism by Heat," _Transactions of the Cambridge Philosophical Society_ (1823), vol. 2, pp. 47-76.

[31] "Account of the New Galvano-Magnetic Condenser invented by M. Poggendorf of Berlin," _Edinburgh Philosophical Journal_ (July 1821), vol. 5, pp. 112-113.

* * * * *

Transcriber's Notes.

The following assumed typographical errors have been corrected:

Page 125: J. B. [Johann Bartholomacus] Tromsdorff--should be Johann Bartholomäus Trommsdorff?

Page 134: "paper of April 2, 1821,[22] is quite"--had "1921."

Footnote 13: "_Geschichte der Elektrizität_"--had "Elektrizitat."

Footnote 16: "_Journal für Chemie und Physik_"--had "and."

One questionable spelling has been retained as follows:

Footnote 20: "Sur le Multiplier electro-magnetique..."--should be "Multiplicateur"?

* * * * *

CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY:

PAPER 39

FULTON'S "STEAM BATTERY": BLOCKSHIP AND CATAMARAN

_Howard I. Chapelle_

SURVIVING DESIGNS FOR FLOATING BATTERIES 145

CONTROVERSIAL DESCRIPTIONS 147

COPENHAGEN PLANS 150

HISTORY OF DOUBLE-HULL CRAFT 152

SAIL AND INBOARD PLANS 157

RECONSTRUCTING THE PLANS 161

APPENDIX 167

FOOTNOTES

_Howard I. Chapelle_

FULTON'S "STEAM BATTERY": BLOCKSHIP and CATAMARAN

_Robert Fulton's "Steam Battery," a catamaran-type blockship, was built during the War of 1812. Until recently, not enough material has been available to permit a reasonably accurate reconstruction of what is generally acknowledged to be the first steam man-of-war._

_With the discovery, in the Danish Royal Archives at Copenhagen, of plans of this vessel, it is now possible to prepare a reconstruction and to build a model._

_This article summarizes the history of the vessel, describes the plans and the reconstruction, and also evaluates its design with particular attention to the double-hull construction._

THE AUTHOR: _Howard I. Chapelle is curator of transportation in the Smithsonian Institution's Museum of History and Technology._

The identity of the first steam man-of-war has been known for many years, and a great deal has been written and published on the history of this American vessel. Until recently, the only available drawing of the ship has been a patent drawing made for Robert Fulton. This does not comply with contemporary descriptions of the steamer and the drawing or plan is out of proportion with the known dimensions. The lack of plans has heretofore made it impossible to illustrate the vessel with any degree of precision, or to build a scale model.

The discovery in 1960 of some of the plans of this historic ship in the Danish Royal Archives at Copenhagen now makes possible a reasonably accurate reconstruction of the vessel and also clarifies some of the incomplete and often confusing descriptions by contemporary writers.

Of the numerous published accounts of the ship that are available, the most complete is David B. Tyler's "Fulton's Steam Frigate."[1] A contemporary description of the vessel by the British Minister to Washington, 1820-23, Stratford Canning, was published by Arthur J. May.[2] In _Naval and Mail Steamers of the United States_, by Charles B. Stuart,[3] and _The Steam Navy of the United States_, by Frank M. Bennett,[4] the history of the ship and some descriptive facts are given. Stuart, in an appendix, gives in full the report of the Supervisory Committee (set up to administer the building contract). Tyler and Stuart, and the Committee Report are the principal sources from which the following summary of the ship's history is drawn.

[Text of Illustration: Plate N^o. 1.

"DEMOLOGOS"

Figure 1^st. _Transverse section A her Boiler. B the steam Engine. C the water wheel. E E her wooden walls 5 feet thick, diminishing to below the waterline as at F.F draught of water 9 feet D D her gun deck_

_Scale 1/12 inch=1 foot_

Waterline

_Scale 1/24 inch=1 foot_

Figure II^d. _This shews her gun deck, 140 feet long 24 feet wide, mounting 20 guns. A the Water wheel_

Figure III^d

_Side View_

_Scale 1/24 inch=1 foot_

ROBERT FULTON

_November 1813._

_S M^c Elroy del._

_"Stuart's Naval & Mail Steamers U.S."_

_Sarony & Major. Eng. N.Y._]

On December 24, 1813, Robert Fulton invited a group of friends--prominent merchants, professional men and naval officers--to his home in New York City and there presented a proposal for a project of great local interest. At that time the War of 1812 was in its second year and the economic effect of the British naval blockade was being felt severely. The blockade cut off seaborne trade and posed a constant threat of attack upon New York and other important ports, particularly Baltimore. To defend the ports, it had been proposed to build mobile floating batteries or heavily built and armed hulks with small sailing rigs, but the high cost of these and their doubtful value in helping to break the blockade, compared to the value and action of a very heavy, large frigate, or a 74-gun ship, caused authorities to hesitate to proceed with the construction of any blockships or floating batteries.

Fulton's proposal concerned a floating battery propelled by steam power. He believed that steam propulsion not only would give it effective maneuverability with no loss of gunpower, but also would allow a successful attack upon the Royal Navy blockading ships during periods of protracted calm, when sailing men-of-war were nearly helpless. The blockaders then could be attacked and picked off, one by one, by the heavily armed steamboat.

Among those present at the meeting was Major General Henry Dearborn, a leading citizen and soldier who was later to become noted in American political history. The first step taken during this meeting was the founding of the Coast and Harbor Defense Company with Dearborn as president, Fulton as engineer, and Thomas Morris as secretary. Next, a committee was established to raise funds from Federal, State, and New York City governments as well as from individual contributors to build the battery. The members of this committee consisted of General Dearborn, Commodore Stephen Decatur, U.S.N.; General Morgan Lewis; Commodore Jacob Jones; U.S.N.; Noah Brown, shipbuilder; Samuel L. Mitchill; Henry Rutgers; and Thomas Morris.

The committee proved cumbersome and was reduced to General Lewis, Issac Bronson, Henry Rutgers, Nathan Sanford, Thomas Morris, Oliver Wolcott, and John Jacob Astor. Known as the Coast Defense Society and with the name of _Pyremon_ given the ship in prospectus, they attempted, unsuccessfully, to raise funds privately.

The estimated sums to build a battery 130 feet long, with a 50-foot beam, capable of a speed of 5 mph, and carrying 24 long guns (18-pdr.), was $110,000. Fulton, still the chief engineer, in an effort to interest the Federal Government, built a model of the proposed vessel and submitted it to some prominent naval officers--Commodore Stephen Decatur, Jacob Jones, James Biddle, Samuel Evans, Oliver Perry, Samuel Warrington, and Jacob Lewis. All gave their support to the Society in a written statement and this recommendation proved helpful to the project in Congress and in the Navy Department. In the process of passing a bill which went to the Senate Naval Affairs Committee calling for $250,000 for the construction of the floating battery, the sum was raised to $1,500,000 for the construction of "one or more" floating batteries and passed on March 9, 1814.

To supervise the start of construction, the Coast Defense Society appointed a committee consisting of Dearborn, Wolcott, Morris, Mitchill, and Rutgers, with Fulton as engineer, and a model and drawing of the proposed vessel was submitted to the Patent Office. The Secretary of the Navy, although supporting the project, delayed action until he had weighed the importance of the batteries in relation to other war needs, for at this time the naval shipbuilding program on the Great Lakes was considered of prime importance. He also raised some technical questions concerning the design of the batteries, which Fulton answered with a description of the vessel as 138 feet on deck, 120 feet on the keel, 55 feet beam (each hull to have a 20-foot beam and the "race" between to be 15 feet wide), draft 8 or 9 feet loaded, and the intended speed was to be 4-1/2 to 5 mph. The ship was to carry 24 long guns (32-pdr.), the engine was to be 130 hp, and the total cost, $200,000. In his letters to the Secretary of the Navy, Fulton stated that Adam and Noah Brown would build the hull for $69,800 and that he would build the engine, machinery and boilers for $78,000, a total of $147,800. He intended to have the boilers, valves, fastenings, and air pumps of brass or copper, which would raise the machinery costs 59 percent above that of stationary engines and boilers then in use.

On May 23, 1814, the Secretary of the Navy authorized the Coast Defense Society and its committee to act as Navy agents and to enter into the contracts required to build a vessel, and to draw on the Navy storekeepers or Navy Yard commandants for such stores or articles on hand needed for construction. The contracts were prepared and the committee now was officially empowered to act for the Society, with Rutgers, Wolcott, Morris, Dearborn, Mitchill, and Fulton. On June 4, Dearborn asked the Navy Department for $25,000 advance, for work had started. On the 6th, he informed the Secretary that he had been ordered to assume command of the defenses of Boston and that Rutgers had been appointed chairman of the construction committee in his place.

It is apparent that the Navy Department was pressed for funds, due to the very extensive shipbuilding programs on Lakes Erie, Ontario, and Champlain in addition to the seagoing vessels being built in some of the coastal ports. This was certainly one cause for the Secretary of the Navy's reluctance to carry out the requirements of the bill passed by Congress immediately after its signature and, also, this reluctance caused the supervisory committee much embarrassment in its administration of the contract.

Another factor which caused difficulty in the administration of the contract was the position of Adam and Noah Brown. The brothers were deeply involved in the shipbuilding program on the Lakes, in which they were associated at times with Henry Eckford. The Browns constructed a blockhouse, shops, and quarters at Erie; in addition to Perry's two brigs and five of his schooners, they also built some of the Lake Ontario vessels and, later, the _Saratoga_ on Lake Champlain. In their New York yard, whose operation continued throughout the war, they built some large letter-of-marques: the _General Armstrong_, _Prince de Neufchatel_, _Zebra_, _Paul Jones_, and some smaller vessels. They also cut down the 2-decked, merchant ship _China_ into a single flush-deck letter-of-marque, renamed _Yorktown_; and they had a contract to build the sloop-of-war _Peacock_. It is remarkable that the Browns could undertake and complete so much work between 1813 and 1815 and still be able to build the steam battery in a very short time.

With the contracts in order, the Browns began building. The keels of the battery were laid June 20, 1814. It is apparent that the Browns prepared the original hull plans, undoubtedly before the building authority was obtained. The vessel required only about four months to build; she was launched October 29, 1814, at 9 a.m. This was an excellent performance, considering the size of the vessel, the amount of timber required and handled in her massive construction, and the other work being done by the builders. During the ship's construction, sightseers were a nuisance and finally guards had to be obtained. During the building of the steam battery, work had to be practically stopped on the sloop-of-war _Peacock_ at one period after she had been partially planked.

There were difficulties in obtaining metalwork for the vessel during her construction, due to the blockade and the demand for such material for other shipbuilding at New York. On November 21, 1814, the ship was towed from the Browns' yard on the East River by Fulton's _Car of Neptune_ and _Fulton_, each lashed to the sides of the battery, and taken to Fulton's works on the North River. There Fulton supervised in person the completion of the vessel and construction of her machinery. Undoubtedly only a little of his time was required in inspection of the Browns' work on the battery, for the shipbuilders had been closely associated with Fulton throughout the life of the project and were fully capable as ship designers. The work on the machinery was another matter, however, for men capable of working metal were scarce and few workmen could read plans. Fulton had some of the work done outside of his own plant, particularly the brass and copper work (mostly by John Youle's foundry). As a result, Fulton was required to move from plant to plant, keeping each job under almost constant observation and personally supervising the workmen. The equipment then available for building a large engine was inadequate in many ways. The large steam cylinder presented a problem: it had to be recast several times and some of the other parts gave trouble, either in casting or in machining and fitting.

Guns for the battery were another problem. Only 3 long guns (32-pdr.), were available at the Navy Yard. The Secretary of the Navy promised some captured guns then at Philadelphia. Because of the blockade, these had to come overland to New York. The captured guns thus obtained were probably English, part of the cargo of the British ship _John of Lancaster_ captured by the frigate _President_ early in the war. Apparently 24 guns were obtained this way; only 2 were obtained from the Navy Yard. In July the Supervising Committee carried out some experimental damage studies, in which a 32-pdr. was fired at a target representing a section of the topsides of the battery. Drawings of the result were sent to the Secretary of the Navy.

Further problems arose over the delays of the government in making payments: the banks discounted the Treasury notes, so the Committee members had to advance $5,000 out of their own pockets. There was fear that British agents might damage the vessel, and although the project was undoubtedly known to the British, no evidence of any act of sabotage was ever found. Captain David Porter was assigned to the command of the battery in November, and it was upon his request that the vessel was later rigged with sails.

With the _Steam Battery_ approaching completion, the Secretary of the Navy became more enthusiastic and the construction of other batteries of this type was again proposed. Captain Stiles, a Baltimore merchant, offered to build a steam battery, the hull to cost $50,000; the entire cost of the vessel, $150,000, was raised in Baltimore and the frames of a battery erected. Another battery was projected at Philadelphia and the Secretary of the Navy wanted one or more built at Sackett's Harbor, but naval officers and Fulton objected. A bill put before Congress to authorize another half million to build steam batteries passed the first reading January 9, 1815, went to the House February 22, 1815, but the end of the war prevented any further action on it.

On February 24, 1815, Fulton died. He had been to Trenton, New Jersey, to attend a hearing on the steamboat monopoly and, on the way back, the ferry on North River was caught in the ice. Fulton and his lawyer, Emmet, had to walk over the ice to get ashore. On the way, Emmet fell through and Fulton got wet and chilled while helping him. After two or three days in bed Fulton went to his foundry to inspect the battery's machinery causing a relapse from which he died. This resulted in some delay in completing the machinery and stopped work on the _Mute_, an 80-foot, manually propelled, torpedo boat that Fulton was having built in the Browns' yard.

It was decided to suspend work on the Baltimore battery after an expenditure of $61,500, but the New York battery was to be completed to prove the project was practical. The final payment of $50,000 was made four months after it was requested.

Charles Stoudinger, Fulton's foreman or superintendent, was able to complete and install the ship's machinery. On June 10, 1815, the vessel was given a short trial run in the harbor with Stoudinger and the Navy inspector, Captain Smith, on board. This trial revealed the need of some mechanical alterations; sails were not used, and it was found she could stem the strong tide and a fresh headwind. The vessel also was visited by the officers of French men-of-war at anchor in the harbor.

On July 4, 1815, she was given another trial. She left Fulton's works at Corlear's Hook at 9 a.m., ran out to Sandy Hook Lighthouse, bore west and returned, a total of 53 miles under steam, reaching her slip at 5:20 p.m. She was found to steer "like a pilot boat." This prolonged trial revealed that the stokehold was not sufficiently ventilated and more deck openings were required. The windsails used in existing hatches were inadequate. The paddle wheel was too low and had to be raised 18 inches, and there were still some desirable modifications to be made in the machinery.

On September 11, 1815, she was again given a trial run. All alterations had been made, including the addition of hatches and raising the paddle wheel, and her battery was on board with all stores, supplies, and equipment. She had 26 long guns (32-pdr.), mounted on pivoted carriages, and now drew 10 feet 4 inches. On this day she left her slip at 8:38 a.m. and went through the Narrows into the Lower Bay, where she maneuvered around the new frigate _Java_ at anchor there. The battery then was given a thorough trial under steam and sail and, with the ship underway, her guns were fired to see if concussion would damage the machinery. The vessel was found to be a practical one, capable of meeting the government's requirements in all respects; her speed was 5-1/2 knots. However, the stokehold temperature had reached 116° Fahrenheit! She returned to her slip at 7:00 p.m.

On December 28, 1815, the Committee in a written report to the Secretary of the Navy,[5] gave a description of the vessel and praised her performance. At this time a set of plans was made by "Mr. Morgan," of whom no other reference has appeared, and sent to the Navy Department. These cannot now be found. The Committee recommended the battery be commissioned and used for training purposes. This suggestion was not followed.

The ship remained in her slip during the winter, and in June 1816 she was turned over to the Navy and delivered to Captain Samuel Evans, commandant of the New York Navy Yard. Captain Joseph Bainbridge was assigned to her command. However, she was not commissioned and soon after her delivery she was housed over and placed "in ordinary," that is, laid up. The final settlement showed that the Committee, as Navy agents, had paid out $286,162.12 with $872.00 unpaid, as well as a claim for $3,364.00 by Adam and Noah Brown, making a total of $290,398.12.

The following year, on June 18, 1817, she was unroofed and put into service with a small crew. With President James Monroe on board, she left the Navy Yard about noon for a short trip to the Narrows and then to Staten Island and returned in the evening. The next day she was again placed "in ordinary."

Four years later, in 1821, when her guns and machinery were removed, it was found that she was rapidly becoming rotten. She was then utilized as a receiving ship. At 2:30 p.m. on June 4, 1829, she blew up, killing 24 men and 1 woman, with 19 persons listed as injured. Among those killed was one officer, Lt. S. M. Brackenridge. Two lieutenants and a Sailing Master were hurt, four midshipmen were severely injured, and five persons were listed as missing. The explosion of 2-1/2 barrels of condemned gunpowder was sufficient, due to her rotten condition, to destroy the ship completely. A Court of Inquiry blamed a 60-year-old gunner, who supposedly entered a magazine with a candle to get powder for the evening gun. It was stated to the court that about 300 pounds of powder in casks and in cartridges was on board the ship at the time.[3]

She was not replaced until the coast-defense steamer _Fulton_ was built in 1837-38, though in 1822 the Navy purchased for $16,000 a "steam galliot" of 100 tons, the _Sea Gull_, to be used as a dispatch boat for the West Indian squadron engaged in suppressing piracy during 1823. In 1825 she was laid up at Philadelphia, and in 1840 she was sold for $4,750.

It is a curious fact that the battery did not receive an official name, as did the sailing blockship on the ways at New Orleans, which at the end of the War of 1812 was officially listed as the _Tchifonta_. Nor was the battery given a number, as were the gunboats. In official correspondence and lists, the steam battery is referred to as the "Fulton Steam Frigate," or as the "Steam Battery," but in later years she was referred to as the "Fulton" or "Fulton the First." Perhaps the explanation is that as she was the only one of her kind she was not numbered, and as she was not considered fit for coastal or extended ocean voyages, she was not given a name.

Surviving Designs for Floating Batteries

The designs of American blockships that have survived are those of the _Tchifonta_,[6] 145 feet long, 43-foot moulded beam, 8-foot 6-inch depth in hold, and about 152 feet 9 inches on deck. She was to carry a battery of 22 long guns (32-pdr.), on the main deck 12 carronades (42-pdr.), on forecastle and quarter decks. She was to have been rigged to rather lofty and very square topgallant sails, and would have been capable of sailing fairly well, though of rather shoal draft, drawing only about 8 feet 6 inches when ready for service. She was sold on the stocks at the end of the war and her later history is not known.

Another and earlier design for a blockship, or floating battery, was prepared by Christian Bergh for Captain Charles Stewart in 1806. This was a sailing vessel for the defense of the port of New York, planned to mount 40 guns (32-pdr.), on her two lower decks and 14 carronades (42-pdr.), on her spar deck. She was to be 103 feet 6 inches between perpendiculars, a 44-foot moulded beam, 10-foot depth of hold, and drawing about 9 feet when ready for service. She was intended to be ship-rigged, but was never built.[7] A few small sloop-rigged block vessels also were built during Jefferson's administration. The sloop-of-war _Saratoga_, built on Lake Champlain by the Browns, in 1813, was practically a blockship. A plan for a proposed "Guard Ship," or "Floating Battery," was made by James Marsh at Charleston, South Carolina, in 1814. This was an unrigged battery, 200 feet extreme length, 50-foot moulded beam, 9-foot depth of hold, to mount 32 guns (42-pdr.), on a flush deck, with a covering deck above.[8]

Through the courtesy of the trustees of the National Maritime Museum, Greenwich, England, the Rigsarkivet, Copenhagen, Denmark, and the Statens Sjöhistoriska Museum, Stockholm, Sweden, the author has been able to illustrate in this article the designs of some of the early floating batteries.

In the last quarter of the 18th century and later, the Danes had built sail-propelled floating batteries or blockships, which were employed in the defense of Copenhagen. The British built at least one sail-propelled battery, the _Spanker_, in 1794. This was a scow of very angular form with overhanging gun-deck, bomb-ketch-rigged, and about 120 feet overall 42-foot 4 inches moulded beam and 8-foot depth of hold. She is said to have been a failure due to her unseaworthy proportions and form; the overhanging gun deck and sides were objected to in particular. She is called a "Stationary Battery" in her plans, which are in the Admiralty Collection of Draughts, National Maritime Museum, Greenwich.

Controversial Descriptions

The contemporary descriptions of the Fulton _Steam Battery_ do not agree. This was in part due to differences between the dimensions given out by Fulton during the negotiations with the Federal Government, and after the ship's construction was authorized. From the context of various statements concerning the projected vessel, such as that of the naval officers, the changes in the intended dimensions of the ship can be seen. For example, the officers state the model and plan shown them would produce a battery carrying 24 guns (24- and 32-pdrs.), and a letter from Fulton to Jones,[9] shows she was to be 138 feet on deck and 55-foot beam. The final reported dimensions, given by the Supervisory Committee,[10] are 156 feet length, 56 feet beam, and 20 feet depth.

In addition there are a few foreign accounts which give dimensions and descriptions. The most complete was probably that of Jean Baptiste Marestier, a French naval constructor who visited the United States soon after the end of the War of 1812 and published a report on American steamboats in 1824.[11] The _Steam Battery_ is barely mentioned though a drawing of one of her boilers is given. Marestier made another report on the American Navy, however. Extensive searches have been made for this in Paris over the last 14 years, but this paper has not been found in any of the French archives. References to the original text indicate that the naval report dealt very extensively with the _Steam Battery_. Some of his comments on the battery appeared in _Procès-verbaux des Séances de l'Académie des Sciences_.[12] Marestier considered the powers of the battery to have been overrated due to fanciful accounts of some laymen writers. He was aware of the shortcomings of the double hull in a steam vessel at the then-possible speeds, but he apparently thought two engines, one in each hull and each with its boilers would be better than Fulton's arrangement of boilers in one hull and engine in the other. He noted that the paddle wheel turned 16-18 rpm and that steam pressure sustained a column of mercury 25 to 35 centimeters. The safety valve was set at 50 centimeters. Fuel consumption was 3-5/8 cords of pine wood per hour.

In view of the access Marestier is known to have had to American naval constructors, shipbuilders, and engineers, it is highly probable that he not only obtained the building plan of the ship but also some of the earlier project plans from the builders and from Fulton's superintendent, Stoudinger. It is, therefore, a great misfortune that his lengthy report on the _Battery_ cannot be produced.

A French naval officer who investigated the ship, M. Montgéry, also wrote a description, published in "Notice sur la Vie et les Travaux de Robert Fulton."[13]

It should be noted in regard to what Montgéry wrote about the _Battery_, that in 1821 it had been considered desirable to disarm the ship. The engineer in charge, William Purcell, had reported that as there were not proper scuppers, dirt and water had entered the hull and had collected under the engine and boilers, causing damage to the hull, and also that with guns removed, the _Battery_ would float too high for the paddle wheel to propel the vessel; so it had been decided to remove all machinery as well as the armament.

Montgéry's description, published in 1822, was taken from his report to the Minister of Marine and Colonies. It noted the battery was made of two hulls separated by a channel, or "race," 15-1/2 feet wide, running the full length of the vessel. The two hulls were joined by a deck just above the waterline, as well as by an upper deck, and also connected at their keels by means of 12 oak beams each 1 foot square. The vessel was 152 feet long, 57 feet beam, and 20 feet deep. Sides were 4 feet 10 inches thick, and the ends of the hull were rounded and alike. There were two rudders at each end, one on each hull, alongside the race. The eight paddle blades, each 14-1/2 feet by 3 feet, turned in either direction by stopping the engine piston at half-stroke and reversing the flow of steam. Rigged with two lateen sails and two jibs, the ship sailed either end first. The engine of 120 hp was in one hull and two boilers were in the other. Other sources, Marestier, and Colden in _Procès-verbaux des Séances de l'Académie des Sciences_,[14] gave additional information (some of it incorrect): the engine was inclined, with a 4-foot-diameter cylinder, 5-foot stroke, direct-connected to the paddle wheel, which was turned at 18 rpm. The boilers were 8 × 22 feet with the fireboxes in inside cylinders, each about 5 feet in diameter, and extending about half the length of the boiler from the fire doors. Two fire tubes, each about 3 feet in diameter, returned the gases from the inside end of the fireboxes to the stacks at the firing end. Except at the fire-door end, the firebox was completely surrounded by water. The boiler pressure of about 6 psi was not maintained, varying somewhat with each stroke of the engine.

Water level in the boilers was indicated by try cocks. The safety valve was controlled by a counterbalanced lever. A jet of salt water was injected into the exhaust trunk to form a vacuum by condensation. An air pump transferred condensate and sea water into a tank from which it passed overboard. Only about a tenth of this water was returned to the boilers.

Montgéry stated also that only the lower or gun deck was to be armed. No bulwarks were on the spar deck, only iron stanchions to which were fastened a breastwork of wet cotton bales when the _Steam Battery_ was in action.

The _Battery_ was designed to carry 30 guns (32-pdr.), with 3 guns in each end and 12 on each side, but no guns in the wake of paddle wheel and machinery. Hatches to give air to the stokehold were located amidships. The _Battery_ was to have been supplemented at the ends of each hull by a Columbiad "submarine gun" (100-pdr.), Fulton's invention, but these were not fitted. Provision was to be made in the fireboxes for heating shot, and a force pump with a cylinder 33 inches in diameter was employed to throw a stream of cold water, about 60-80 gallons per minute, for a distance of about two hundred feet. This could be done only when the paddle wheel was not in operation. The paddle wheel was housed, the top fitted with stairs to the spar deck. The gun deck, over the race, was used in part for staterooms, of which the bulkheads were permanent. Hammocks for the complement of 500 men were to be slung on the rest of the gun deck. The ship drew 10 feet 4 inches, with the port sills about 5-1/2 feet above the loadline. Burning wood, the vessel could carry about 4 days' supply of fuel; burning coal, she carried 12 days' supply.

Montgéry said that the vessel would be vulnerable to bombshells and hot shot, and that furthermore she could be boarded. The displacement of the ship, at service draft, was 1,450 tons, a figure Montgéry obtained from a copy of the original plan given him by Noah Brown.

In 1935, Lieutenant Ralph R. Gurley, USN, attempted a reconstruction in sketches of the vessel published in his article "The U.S.S. _Fulton_ the First" in the _U.S. Naval Institute Proceedings_.[15] This reconstruction was based on the Patent Office drawing prepared for Fulton, and published by Stuart and Bennett, and the foregoing French sources. The Patent Office drawing showed the engine was an inclined cylinder and Lt. Gurley shows this in his sketch; in his text (p. 323) he says, "The engine was an inclined, single-cylinder affair with a 4-foot base and a 5-foot stroke." Gurley's attempt to reconstruct the _Steam Battery_ is the only one known to the author.

Copenhagen Plans

In 1960, Kjeld Rasmussen, naval architect of the Danish Greenland Company, was requested by the author to inspect in the Danish Royal Archives at Copenhagen a folio of American ship plans, the index of which had listed some Civil War river monitors. Mr. Rasmussen found the monitor plans had been withdrawn but discovered that three plans of Fulton's _Steam Battery_ existed, as well as plans of the first _Princeton_, a screw sloop-of-war.

Copies of the _Steam Battery's_ plans were obtained at Copenhagen in September 1960 through the courtesy of the archivist, and were found to consist of the lines, copied in 1817, an inboard profile and arrangement, and a sail and rigging plan. From these the reconstruction for a scale model was drawn and is presented here with reproductions of the original drawings upon which the reconstruction is based.

It is apparent that Montgéry's description is generally accurate. The vessel is a catamaran, made of two hulls, double-ended and exactly alike. The outboard sides are "moulded," with round bilges, the inboard sides are straight and flat, as though a hull had been split along the middle line and then planked up flat where split. The hulls are separated by the race, in which the paddle wheel is placed at mid-length. The topsides are made elliptical at the ends, and the midsection shows a marked tumble-home over the thick topside planking but less on the moulded lines.

The lines plan agreed rather closely to Montgéry's description of the hull. After careful fairing it was found the lines drawing would produce a vessel 153 feet 2 inches overall outside the stems, or about 151 feet over the planked rabbets, with a moulded beam of 56 feet and extreme beam of 58 feet. The moulded depth was 22 feet 9 inches and the width of the race was 14 feet 10 inches, plank to plank. The room and space of framing shown was 2 feet. The designed draft appears to be 13 feet and this would bring the port sills 5 feet 6 inches above the loadline and the underside of the gun-deck beams about 2 feet 9 inches above the loadline.

The lines plan is a Danish copy, probably of the building plan by Noah Brown, and may be based on the plan Montgéry obtained from Brown. The spar deck has the iron stanchions (Gurley translated these as "chandeliers") which are set inboard 4 feet from the plank-sheer. This gives room for cotton bales, outboard the stanchions, to form a barricade. As will be seen by comparing the original Danish drawing with the model drawing, the construction indicates that the iron stanchions should be carried around the ends of the hull in the same manner as along the sides, since the lower ends of the iron stanchions pass through the spar deck and are secured to the inside of the inner ceiling of the gun deck. The rudders are as shown in the Danish drawing, and it is supposed that they were operated ferryboat fashion, one at each end of the vessel. Hence, each pair of rudders was toggled together by a cross-yoke. This was probably operated by a tiller (possibly the cross-yokes and tillers were of iron) pivoted under the beams of the gun deck close to the ends of the ship. Tiller ropes led from a tackle under the gun-deck through trunks to the spar deck, where the wheels were placed. This allowed proper sweep to the tillers and operation of each pair of rudders. The paddle wheel was apparently of iron, with wooden blades, and agrees with Montgéry's description. In the plan for the model it is shown raised 18 inches above the original design position, to agree with trial requirements.

It should be observed that the close CL-to-CL frame spacing created a hull having frames touching one another, at least to above the turn of the bilge, so the vessel was almost solid timber, before being planked and ceiled, from keel to about the loadline. The sides are not only heavily planked but, after the frames were ceiled with extraordinarily heavy, square timbering, a supplementary solid, vertical framing was introduced inboard and another ceiling added. The sides scale about 5 feet from outside the plank to the inboard face of the inner ceiling at the level of the gunports.

The hulls were tied together athwartship by the deck beams of the gun deck and spar deck, except in the wake of the paddle wheel. Knees were placed along the sides of the race at alternate gun-deck beams. In addition, the 12 1-foot-square timbers, crossing the race at the rabbets of the hulls, (mentioned by Montgéry) are shown. These must have created extraordinary resistance, even at the low speed of this steamer. The deck details shown are the results of reconstruction of the inboard works.

History of Double-Hull Craft

The use of catamaran hulls, or "double-hulls," has been periodically popular with ship designers since the time of Charles II of England. The earliest of such vessels known in the present day were four sloops or shallops designed 1673-1687 by Sir William Petty, who was an inventor in the field of naval architecture and received some attention from Charles II and from the Royal Society.

The first Petty experiment, the _Simon & Jude_, later called _Invention I_, was launched October 28, 1662. She was designed with two hulls cylindrical in cross section, each 2 feet in diameter, and 20 feet long. A platform connected the hulls, giving the boat a beam of a little over 9 feet. She had a 20-foot mast stepped on one of the crossbeams connecting the hulls, with a single gaff sail. In sailing trials she beat three fast boats: the King's barge, a large pleasure boat, and a man-of-war's boat. This "double-bottom," also called a "sluiceboat" or "cylinder," was later lengthened at the stern to make her 30 feet overall.

The King did not support Petty, to the latter's great disappointment, and Petty next built a larger double-bottom, _Invention II_. This catamaran was lapstrake construction. Not much is known of this boat except that she beat the regular Irish packet boat, running between Holyhead and Dublin, in a race each way, winning a £20 wager. She was launched in July 1663; what became of her was not recorded.

A third and still larger boat, the _Experiment_, launched December 22, 1664, appears to have been a large sloop. This vessel sailed by way of the Thames in April 1665 and went to Oporto, Portugal. She left Portugal October 20, 1665, for home, but apparently went down with all hands in a severe storm.

For 18 years Petty did no more with the type, but finally, in July 1684, he laid down a still larger sloop with two decks and a mast standing 55 feet above her upper deck. She was named _St. Michael the Archangel_ and is probably the design in Pepys' _Book of Miscellaneous Illustrations_ in Magdalene College, Cambridge, England. This vessel proved unmanageable and was a complete failure.

Though the double canoes of the Pacific Islands were probably known to some in Europe in 1662, there is no evidence that Petty based his designs on such craft. He appears to have produced his designs spontaneously from independent observations and resulting theories. Before Petty concluded his experiments, a number of double-hull craft had been produced by others; however, some "double" craft, such as "double shallops" may have been "double-enders," as shown by a "double-moses boat" of the 18th century and later.[16]

The use of two canoes, joined by a platform or by poles was common in colonial times; in Maryland and Virginia, dugouts so joined were used to transport tobacco down the tidal creeks to vessels' loading. Such craft were also used as ferries. M. V. Brewington's _Chesapeake Bay Log Canoes_[17] and Paul Wilstack's _Potomac Landings_[18] illustrate canoes used in this manner. A catamaran galley, two round-bottom hulls, flat on the inboard side (a hull split along the centerline and the inboard faces planked up), 113 feet long and each hull a 7-foot moulded beam, 6-foot 6 inches moulded depth, and placed 13 feet apart, was proposed by Sir Sidney Smith, R.N., in the 1790's, and built by the British Admiralty. Named _Taurus_, she is shown by the Admiralty draught to have been a double-ender, with cabins amidships on the platform, an iron rudder at each end (between the hulls) steered with tillers (to unship), and with a ramp at one end. The plans are undated, signed by Captain Sir Sidney Smith, and a field-carriage gun is shown at the ramp end of the boat. This, and the heavy rocker in the keels, suggests the _Taurus_ was intended for a landing boat. No sailing rig is indicated, but tholes for 12 oars or sweeps on each side are shown. The oarsmen apparently sat on deck, or on low seats, with stretchers in hatches between each pair of tholes (Admiralty Collection of Draughts, The National Maritime Museum, Greenwich, England).

Another experimenter with the double-hull type of vessel was a wealthy Scot named Patrick Miller who was particularly interested in manual propulsion of vessels, employing geared capstans to operate paddle wheels. In a letter dated June 9, 1790, Miller offered Gustav III of Sweden a design for a double-hulled 144-gun ship-of-the-line (rating as a 130-gun ship) propelled by manually operated capstans connected to a paddle wheel between the hulls. She was rigged to sail, with five masts and was to be 246 feet long, 63 feet beam, and 17 feet draft; the hulls were 16 feet apart.

This project was submitted by the King to Fredrik Henrik af Chapman, the great Swedish naval architect, who made an adverse report. Chapman pointed out in great detail that the weight of the armament, the necessary hull structure, the stores, crew, ammunition, spars, sails, rigging and gear, would greatly exceed Miller's designed displacement. He also pointed out the prime fault of catamarans under sail--slow turning in stays. He suggested that the speed under sail would be disappointing. He doubted that a double-hull ship of such size could be built strong enough to stand a heavy sea. He remarked that English records showed that a small vessel of the catamaran type had been built between 1680 and 1700 which had sailed well (this may have been one of Petty's boats), and that "36 years ago" he had seen 8 miles from London, a similar boat that had been newly built by Lord Baltimore and was about 50 feet long; this was a failure and was discarded after one trial. Therefore, said Chapman, the Miller project was not new but rather an old idea. Chapman's final remark is perhaps the best illustration of his opinion of the catamaran, "Despite all this, two-hull vessels are completely sound when the theory can be properly applied; that is in vessels of very light weight, and of small size, with crews of one or two men."

A "model" of such a double-hull ship--the _Experiment_, built at Leith, Scotland, in 1786 by J. Laurie--was sent to Sweden by Miller. She was 105 feet long, 31 feet beam, and cost £3000. This vessel arrived in the summer of 1790 and King Gustav in a letter dated July 26 ordered Col. Michael Anckerswärd to welcome the vessel at Stockholm. The King presented Miller with a gold snuffbox and a painting was made of the vessel. The _Experiment_ had five paddle wheels in tandem between her hulls, operated by geared capstans on deck. These gave her a speed of 5 knots but caused the crew to suffer from exhaustion in a short time. The vessel was badly strained in a storm and was finally abandoned at St. Petersburg, Russia.[19]

Miller later turned to the idea of employing steam instead of manual power and built a 25-foot double-hulled pleasure boat of iron fitted with a steam engine built by William Symington. Also named _Experiment_, she was an apparent success, so Miller had a 60-foot boat built of the double-hull design and fitted with an engine built by Symington. She reached a speed of 7 mph on the Forth and Clyde Canal. However, Miller lost interest when he found that the Symington engine was unreliable and that Great Britain showed very little public support for such projects.

Fulton was acquainted with Symington's work and probably had heard of Miller's vessels. At any rate, he employed the double-hull principle in his steam ferryboats, the first of which was the _Jersey_, a 188-ton vessel built by Charles Browne, which began service July 2, 1812. The next year he had a sister ship built, the _York_. These vessels were based on his patent drawing of 1809. In 1814 he had another vessel of this type built, the _Nassau_. It was, therefore, logical that he should apply this design to the _Steam Battery_. The double-hull design had worked well in these ferries, and the design would give protection from shot to the paddle wheel. The _Battery_ would have the ability to run forward or astern so as not to be exposed to a raking fire from the enemy while maneuvering in action. The application of this "ferryboat" principle to the _Battery_ reduced the need for extreme maneuverability, the catamaran's weakest point, even at low speed.

The resistance factors in the design are of relatively small importance, for the speed possible under steam in this period was very low. However, the plans show an apparently efficient hull form for the power available, aside from the drag of the beams across the race in the vicinity of the keel. The displacement was adequate. The height of the gun-deck above the water at the race made the _Battery_ unsuitable for rough-water operation, but there is no evidence that Fulton or the sponsors of the vessel considered the _Battery_ as a coastwise or seagoing steamer. However, the clearance of the gun deck above the water and the dip of the paddle wheel would have made the additional weight of an upper- or spar-deck battery prohibitive even had experience in action proven it desirable.

Sail and Inboard Plans

The sail and rigging plan is likewise a Danish copy and shows the two-masted lateen rig employed. The hull is shown with bulwarks and gunports on the spar deck but no other evidence that the _Battery_ was finished in this manner has been found. The rig resembles that of some of Josiah Fox's designs for Jeffersonian gunboats--double-enders designed to sail in either direction but without the jibs. The topmasts do not appear to be more than signal poles and apparently were not fitted with sails; however, some European lateeners did have triangular topsails over a lateen and it is possible the _Battery_ may have carried such sails. Considering the stability and displacement of the _Battery_, the rig is very small and not sufficiently effective. Shrouds were not required; the masts were supported by runners that were shifted when the yards were reversed, and in tacking. Apparently the jibstays also could be slacked off so that the lateen yards would not have to be dipped under them.

The inboard profile is on tracing paper and the notes are in French. This drawing is of a simplified hull form having flat-bottom hulls with chines. It is possible that this is a tracing of a preliminary drawing obtained by Marestier or Montgéry, but no documentation can be found. Its importance is that it shows in some detail the engine and boilers, as well as the wheelbox, and another drawing of the paddle wheel, more or less duplicating the wheel shown in the Danish plan. No details of the deck arrangements are shown in any of the plans, except for the dome skylight over the fireroom in the boiler hull.

Both the lines plan and the inboard drawing show construction midsections and hull connections. These plans show that the engine was not inclined, but rather was vertical, contrary to Fulton's patent drawing. The piston rod and the crosshead obviously passed through its gun deck in a large hatch. Also it is plain that there must have been large hatches afore and abaft the wheelbox to make the stepped wheelbox construction desirable. There also must have been a hatch in the gun deck under the domed skylight. It is improbable that the engine and skylight hatches were used for ladderways, passing scuttles, or companionways.

The boilers are shown in the inboard profile about as described and drawn by Marestier but with two stacks on each boiler, one to each flue; Marestier's sketch in his report on American steamships shows the flues of each boiler trunked into a single stack. The battery had two boilers and the stacks are at the boilers' fire-door end. The steam lines came off the crown of the boilers and probably passed through the ends of the wheelbox to the engine; a trunk for the steam lines would undoubtedly have been necessary.

The engine is shown to have had counterbalanced side levers, one on each side, and a single flywheel on the outboard side. The cylinder is over the condenser or "cistern," connected by the steam line and valve box on the side. The cylinder crosshead is shown in the inboard profile to have reached the underside of the beams of the upper deck. The crosshead was connected by two connecting rods to the side levers. These levers operated the paddle wheel by connecting rods to cranks on the paddle-wheel shaft. There is another pair of connecting rods from the side levers to the crosshead of the air pump. All connecting rods are on one arm of the side levers, the other end having only a counterbalance weight beyond the fulcrum bearing. The flywheel has a shaft fitted with two gears, and is driven through idler gears from gears on the paddle-wheel shaft; it turns at about twice the speed of the paddle wheel. No other pumps or fittings are shown in the engine hull, although manual pumps were probably fitted to fill and empty the boilers. Piping is not shown.

The four rudders, toggled in pairs, are shown in both the lines and inboard drawings, but the shape is different in the two plans. Operation must have been by a tiller under the gun-deck beams. The outer end of the tiller may have been pivoted on the toggle bar and the inboard end fitted, as previously described, with steering cable or chain tackles. This seems to be the only practical interpretation of the evidence.

Reconstructing the Plans

In the model it was necessary to reconstruct the deck arrangements without enough contemporary description. The outboard appearance and hull form, rig, and arrangement of armament require no reconstruction, for all that is of importance is shown in the lines and rig drawings, or in the inboard profile. The masts are shown to have been stepped over the race on the gun deck. The iron stanchions are shown in the lines drawing and in the construction section. However, their position at the ends of the _Battery_ are apparently incorrectly shown in the original lines plan. The construction section shows these stanchions to have been stepped on the inside face of the inner ceiling and, as the ceiling structure was carried completely around the ship, the stanchions in the ends must have been placed inboard, as along the sides. The bowsprit was above deck and would probably be secured in the knighthead timbers at the ends of the hull, as well as by the heel bitts shown in the Danish lines drawing. With the riding bitts shown inboard of the heel bitts at each end of the vessel, it is obvious that she would work her ground tackle at both ends and would therefore require two capstans; the wheelbox would prevent effective use of a single one. The capstans might be doubleheaded, as in some large frigates and ships-of-the-line.

As to the remaining deck fixtures, hatches and fittings, these must be entirely a matter of speculation. Ladderways, passing scuttles, hatches, trunks, galley, heads and cabins were obviously required in a fighting ship and can only be located on the theory that, when completed, the _Battery_ was a practical vessel.

It has been stated that the officers' cabins were over the race; the logical place for the heads, galley, wardroom and mess also would be over the race, giving the remaining part of the gun deck for the necessary hatches, ladderways, trunks, etc., in the two hulls, space required for armament, and to sling the hammocks of a watch below. As the vessel was never fully manned, apparently, the space for hammocks is not a serious problem in a reconstruction. If the vessel had been manned as proposed by 500 men, hammocks for over 200 would have been required, which would give very crowded quarters in view of the limited space available.

Though no specific requirements were stated in the reports of the trials, it seems reasonable to suppose that additional hatches were cut in the decks to improve the fireroom ventilation. In the reconstruction drawings, these hatchways as well as the other deck openings and deck fittings--such as bilge pumps, companionways, skylights, binnacles, wheels and wheel-rope trunks, cable trunks, steampipe casings, and stack fiddleys--have been located in an effort to meet the imagined requirements of the working of a ship of this unusual form.

There are some unanswered questions that arose in the preparation of the reconstruction drawings. As has been shown, the original inboard arrangement plan found in Copenhagen shows four smokestacks, while Marestier's sketch of the vessel's boilers shows trunked flues indicating that two stacks were used. It is possible that the boilers were first fitted so that four stacks were required; alterations made as a result of steaming trials may well have included the introduction of trunked flues and the final use of two stacks in line fore-and-aft. This would have required a rearrangement of the fiddley hatches amidships.

Another troublesome question was the doubtful arrangement of the four companionways on the spar deck. Perhaps only two were fitted, one on each side of the officers' staterooms while the ladderways at the crew's end of the ship were simple ladder hatches.

The decision to use four bilge pumps is based upon the lack of drag in the keel of the hulls, which would prevent accumulation of bilge water at one end of the hull. The use of four single-barrel pumps instead of four double-barrel pumps may be questioned, for chain pumps requiring two barrels would have been practical.

Allowance for stores was made by use of platforms in the hold. It is known from statements made to the Court of Inquiry, that the magazines were amidships and that a part of these was close to the boilers. Fuel and water would be in the lower hold under the platforms; hatches and ladderways are arranged to permit fueling the ship.

A few prints or drawings of the ship, aside from the patent drawing, have been found. There are two prints that show the launch of the vessel. One, a print of 1815, is in possession of the Mariners' Museum, Newport News, Va., and is reproduced in Alexander Crosby Brown's _Twin Ships, Notes on the Chronological History of the Use of Multiple Hulled Vessels_.[20] A poor copy of this print appears on page 13 of Bennett's _Steam Navy of the United States_, and another and inaccurate sketch is shown on page 8. These pictures were of no use in the reconstruction as they show no details that are not in the Copenhagen plans. The patent drawing does not show deck details and in fact does not represent the vessel as built in any respect other than in being a catamaran with paddle wheel amidships between the hulls.

The _Steam Battery_ did not have any particular influence on the design of men-of-war that followed her. In the first place, steampower was not viewed with favor by naval officers generally. This was without doubt due to prejudice, but engines in 1820-30 were still unreliable when required to run for long periods, as experienced by the early ocean-going steamers. The great weight of the early steam engines and their size in relation to power were important, and also important were practical objections that prevented the design of efficient naval ocean steamers until about 1840; even then, the paddle wheels made them very vulnerable in action. Until the introduction of the screw propellor it was not possible to design a really effective ocean-going naval steamer; hence until about 1840-45, sail remained predominant in naval vessels for ocean service, and steamers were accepted only in coast defense and towing services, or as dispatch vessels.

No immediate use of the double hull in naval vessels of the maritime powers resulted from the construction of the _Steam Battery_. The flat-bottom chine-built design employed by Fulton in _North River_, _Raritan_, and other early steamboats was utilized in the design for a projected steamer by the British Admiralty in 1815-16. This vessel was about 76 feet overall, 16-foot beam, and 8-foot 10 inches depth in hold. Her design was for a flat-bottom, chine-built hull with no fore-and-aft camber in the bottom, a sharp entrance, and a square-tuck stern with slight overhang above the cross-seam. Her side frames were straight and vertical amidships, but curved as the bow and stern were approached. She was to be a side-paddle-wheel steamer, and her hull was diagonally braced; the wheel and engine were to be about amidships where she was dead flat for about 14 feet. However, the engine and boilers were not installed; the engine was utilized ashore for pumping, and the vessel was completed in the Deptford Yard as a sailing ship. Under the name _Congo_ she was employed in the African coast survey. Her plan is in the Admiralty Collection of Draughts, at the National Maritime Museum, Greenwich, England.

The double hull continued to be employed in both steam and team ferryboats in the United States and in England and France. A few river and lake steamers were also built with this design of hull. Continued efforts to obtain fast sailing by use of the double hull produced a number of sailing catamarans; of these the Herreshoff catamarans of the 1870's showed high speed when reaching in a fresh breeze.

Designs for double-hulled steamers appeared during the last half of the 19th century; in 1874 the _Castalia_, a large, double-hull, iron, cross-channel steamer, was built by the Thames Iron-works Company at Blackwall, England. She was 290 feet long, and each hull had a beam of 17 feet. The paddle wheel was placed between the hulls and, ready for sea, she drew 6-1/2 feet. She ran the 22 miles between Dover and Calais in 1 hour and 50 minutes, a speed much slower than that of the paddle-wheel, cross-channel steamers having one hull. Another double-hull steamer was built for this service by Hawthorn, Leslie and Company, Newcastle-on-Tyne, Scotland, in 1877. First named _Express_, she was renamed _Calais-Douvres_ when she went into service in May 1878. Her length was 302 feet, her extreme beam 62 feet, and each hull had a beam of 18 feet, 3 inches. She drew 6-foot 7-1/2 inches ready for sea and the paddle wheel was between the hulls. On her trials she made 14 knots and burned coal excessively. Sold to France in 1880, she was taken out of service in 1889. Though popular, she was not faster than the single-hull steamers in this service and had been a comparatively expensive vessel to build and operate.

The many attempts to produce a very fast double-hull steamer and large sailing vessels have led to disappointment for their designers and sponsors. In the history of naval architecture, since Petty's time, there have been a number of periods when the new-old idea of the double hull has become popular. Craft of this type have been commonly well publicized but, on the whole, their basic designs have followed the same principles over and over again and have not produced the sought-for increase in speed and handiness.

In very recent years there has been a revival in interest in sailing double-hull boats that is enthusiastic as to very small craft and somewhat restrained as to large boats. A few projects are under development for double-hull craft, power and sail, of over 90-foot length, including an oceanographic research vessel. In general, however, the performance of double-hull boats has shown that Chapman's estimate of the type was reasonably correct and that there are limitations, particularly in maneuverability in the double-hull craft that could have been found by reference to the history of past experiments with the type.

NAVAL STEAMERS.

THE DEMOLOGOS; OR, FULTON THE FIRST.

At the close of the year eighteen hundred and thirteen, Robert Fulton exhibited to the President of the United States, the original drawing from which the engraving on Plate One is sketched, being a representation of the proposed war-steamer or floating-battery, named by him, the Demologos. This sketch possesses more than ordinary interest, from the circumstance that it is, doubtless, the only record of the _first war-steamer in the world_, designed and drawn by the immortal Fulton, and represented by him to the Executive, as capable of carrying a strong battery, with furnaces for red hot shot, and being propelled by the power of steam, at the rate of _four_ miles an hour.

It was contemplated that this vessel, besides carrying her proposed armament on deck, should also be furnished with submarine guns, two suspended from each bow, so as to discharge a hundred pound ball into an enemy's ship at ten or twelve feet below her water-line. In addition to this, her machinery was calculated for the addition of an engine which would discharge an immense column of water upon the decks, and through the port-holes of an enemy, making her the most formidable engine for warfare that human ingenuity has contrived.

The estimated cost of the vessel was three hundred and twenty thousand dollars, nearly the sum requisite for a frigate of the first class.

The project was zealously embraced by the Executive, and the national legislature in March, eighteen hundred and fourteen, passed a law, authorizing the President of the United States to cause to be built, equipped, and employed, one or more floating batteries, for the defense of the waters of the United States.

The building of the vessel was committed by the Coast and Harbor Defense Association, to a sub-committee of five gentlemen, who were recognized by the Government as their agents for that purpose, and whose interesting history of the Steam Frigate is copied in Note A, of the Appendix to this volume.

Robert Fulton, whose soul animated the enterprise, was appointed the engineer; and on the twentieth day of June, eighteen hundred and fourteen, the keel of this novel steamer was laid at the ship-yard of Adam and Noah Brown, her able and active constructors, in the city of New York, and on the twenty-ninth of the following October, or in little more than four months, she was safely launched, in the presence of multitudes of spectators who thronged the surrounding shores, and were seen upon the hills which limited the beautiful prospect around the bay of New York.

The river and bay were filled with steamers and vessels of war, in compliment to the occasion. In the midst of these was the enormous floating mass, whose bulk and unwieldy form seemed to render her as unfit for motion, as the land batteries which were saluting her.

In a communication from Captain David Porter, U. S. Navy, to the Hon. Secretary of the Navy, dated New York, October 29, 1814, he states,--"I have the pleasure to inform you that the "FULTON THE FIRST," was this morning safely launched. No one has yet ventured to suggest any improvement that could be made in the vessel, and to use the words of the projector, '_I would not alter her if it were in my power to do so._'

"She promises fair to meet our most sanguine expectations, and I do not despair in being able to navigate in her from one extreme of our coast to the other. Her buoyancy astonishes every one, she now draws _only eight feet three inches water_, and her draft will only be _ten_ feet with all her guns, machinery, stores, and crew, on board. The ease with which she can now be towed with a single steamboat, renders it certain that her velocity will be sufficiently great to answer every purpose, and the manner it is intended to secure her machinery from the gunner's shot, leaves no apprehension for its safety. I shall use every exertion to prepare her for immediate service; her guns will soon be mounted, and I am assured by Mr. Fulton, that her machinery will be in operation in about six weeks."

On the twenty-first of November, the Steam Frigate was moved from the wharf of Messrs. Browns, in the East River, to the works of Robert Fulton, on the North River, to receive her machinery, which operation was performed by fastening the steamboat "Car of Neptune," to her larboard, and the steamboat "Fulton," to her starboard side; they towed her through the water from three and a-half to four miles per hour.

The dimensions of the "Fulton the First" were:--

Length, one hundred and fifty-six feet.

Breadth, fifty-six feet.

Depth, twenty feet.

Water-wheel, sixteen feet diameter.

Length of bucket, fourteen feet.

Dip, four feet.

Engine, forty-eight inch cylinder, and five feet stroke.

Boiler, length, twenty-two feet; breath, twelve feet; and depth, eight feet.

Tonnage, two thousand four hundred and seventy-five.

By June, eighteen hundred and fifteen, her engine was put on board, and she was so far completed as to afford an opportunity of trying her machinery. On the first of June, at ten o'clock in the morning, the "Fulton the First," propelled by her own steam and machinery, left the wharf near the Brooklyn ferry, and proceeded majestically into the river; though a stiff breeze from the south blew directly ahead, she stemmed the current with perfect ease, as the tide was a strong ebb. She sailed by the forts and saluted them with her thirty-two pound guns. Her speed was equal to the most sanguine expectations; she exhibited a novel and sublime spectacle to an admiring people. The intention of the Commissioners being solely to try her enginery, no use was made of her sails. After navigating the bay, and receiving a visit from the officers of the French ship of war lying at her anchors, the Steam Frigate came to at Powles' Hook ferry, about two o'clock in the afternoon, without having experienced a single unpleasant occurrence.

On the fourth of July, of the same year, she made a passage to the ocean and back, and went the distance, which, in going and returning, is fifty-three miles, in eight hours and twenty minutes, without the aid of sails; the wind and tide were partly in her favor and partly against her, the balance rather in her favor.

In September, she made another trial trip to the ocean, and having at this time the weight of her whole armament on board, she went at an average of five and a half miles an hour, with and against the tide. When stemming the tide, which ran at the rate of three miles an hour, she advanced at the rate of two and a-half miles an hour. This performance was not more than equal to Robert Fulton's expectations, but it exceeded what he had premised to the Government, which was that she should be propelled by steam at the rate of from three to four miles an hour.

The English were not uninformed as to the preparations which were making for them, nor inattentive to their progress. It is certain that the Steam Frigate lost none of her terrors in the reports or imaginations of the enemy. In a treatise on steam vessels, published in Scotland at that time, the author states that he has taken great care to procure _full_ and _accurate_ information of the Steam Frigate launched in New York, and which he describes in the following words:--

"Length on deck, _three hundred feet_; breadth, _two hundred feet_; thickness of her sides, _thirteen feet_ of alternate oak plank and cork wood--carries forty-four guns, four of which are _hundred pounders_; quarter-deck and forecastle guns, forty-four pounders; and further to annoy an enemy attempting to board, can discharge _one hundred gallons of boiling water in a minute_, and by mechanism, brandishes _three hundred cutlasses_ with the utmost regularity over her gunwales; works also an equal number of heavy iron pikes of great length, darting them from her sides with prodigious force, and withdrawing them every quarter of a minute"!!

The war having terminated before the "_Fulton the First_" was entirely completed, she was taken to the Navy Yard, Brooklyn, and moored on the flats abreast of that station, where she remained, and was used as a receiving-ship until the fourth of June, eighteen hundred and twenty-nine, when she was blown up. The following letters from Commodore Isaac Chauncey (then Commandant of the New York Navy Yard) to the Honorable Secretary of the Navy, informing him of the distressing event, concludes this brief history of the _first steam vessel of war ever built_.

* * * * *

U. S. NAVY YARD, NEW YORK, _June 5th, 1829_.

SIR:

It becomes my painful duty to report to you a most unfortunate occurrence which took place yesterday, at about half past two o'clock, P. M., in the accidental blowing up of the Receiving Ship Fulton, which killed twenty-four men and a woman, and wounded nineteen; there are also five missing. Amongst the killed I am sorry to number Lieutenant S. M. Brackenridge, a very fine, promising officer, and amongst the wounded are, Lieutenants Charles F. Platt, and A. M. Mull, and Sailing-Master Clough, the former dangerously, and the two last severely; there are also four Midshipmen severely wounded. How this unfortunate accident occurred I am not yet able to inform you, nor have I time to state more particularly; I will, as soon as possible, give a detailed account of the affair.

I have the honor to be, Sir, Very respectfully, J. CHAUNCEY.

HON. JOHN BRANCH, _Secretary of the Navy, Washington._

U.S. NAVY YARD, NEW YORK, _June 8th, 1829_.

Sir:

I had been on board the "Fulton" all the morning, inspecting the ship and men, particularly the sick and invalids, which had increased considerably from other ships, and whom I had intended to ask the Department permission to discharge, as being of little use to the service. I had left the ship but a few moments before the explosion took place, and was in my office at the time. The report did not appear to me louder than a thirty-two pounder, although the destruction of the ship was complete and entire, owing to her very decayed state, for there was not on board, at the time, more than two and a-half barrels of damaged powder, which was kept in the magazine for the purpose of firing the morning and evening gun. It appears to me that the explosion could not have taken place from accident, as the magazine was as well, or better secured, than the magazines of most of our ships, yet it would be difficult to assign a motive to those in the magazine for so horrible an act, as voluntarily to destroy themselves and those on board. If the explosion was not the effect of design, I am at a loss to account for the catastrophe.

I have the honor to be, Sir, Very respectfully, J. CHAUNCEY.

HON. JOHN BRANCH, _Secretary of the Navy, Washington_.

APPENDIX.

NOTE A.

STEAM FRIGATE.

_Report of HENRY RUTGERS, SAMUEL L. MITCHEL, and THOMAS MORRIS, the Commissioners superintending the construction of a steam vessel of war, to the Secretary of the Navy._

NEW YORK, _December 28th, 1815_.

SIR:

The war which was terminated by the treaty of Ghent, afforded, during its short continuance, a glorious display of the valor of the United States by land and by sea--it made them much better known to foreign nations, and, what is of much greater importance, it contributed to make them better acquainted with themselves--it excited new enterprises--it educed latent talents--it stimulated to exertions unknown to our people before.

A long extent of coast was exposed to an enemy, powerful above every other on the ocean. His commanders threatened to lay waste our country with fire and sword, and, actually, in various instances, carried their menaces into execution. It became necessary, for our defense, to resist, by every practicable method, such a formidable foe.

It was conceived, by a most ingenious and enterprising citizen, that the power of Steam could be employed to propel a floating battery, carrying heavy guns, to the destruction of any hostile force that should hover on the shores, or enter the ports of our Atlantic frontier. The perfect and admirable success of his project for moving boats containing travelers and baggage by the same elastic agent, opened the way to its employment for carrying warriors and the apparatus for fighting.

The plan was submitted to the consideration of the executive of an enlightened government. Congress, influenced by the most liberal and patriotic spirit, appropriated money for the experiment, and the Navy Department, then conducted by the honorable William Jones, appointed commissioners to superintend the construction of a convenient vessel under the direction of ROBERT FULTON, the inventor, as engineer, and Messrs. Adam and Noah Brown, as naval constructors. The enterprise, from its commencement, and during a considerable part of its preparatory operations, was aided by the zealous co-operation of Major General Dearborn, then holding his head-quarters at the city of New York, as the officer commanding the third military district. The loss of his valuable counsel in conducting a work which he had maturely considered, and which he strongly recommended, was the consequence of his removal to another section of the Union, where his professional talents were specially required.

The keels of this steam-frigate were laid on the twentieth day of June, eighteen hundred and fourteen. The strictest blockade the enemy could enforce interrupted the coasting trade, and greatly enhanced the price of timber. The vigilance with which he guarded our coast against intercourse with foreign nations, rendered difficult the importation of copper and iron. The same impediment attended the supplies of coal heretofore brought to New York from Richmond and Liverpool. Lead, in like manner, was procured under additional disadvantages. These attempts of the enemy to frustrate the design, were vain and impotent. All the obstacles were surmounted. Scarcity of the necessary woods and metals were overcome by strenuous exertions; and all the blockading squadron could achieve, was not a disappointment in the undertaking, but merely an increase of the expense.

So, in respect to tradesmen and laborers, there was an extraordinary difficulty. Shipwrights had repaired to the lakes, for repelling the enemy, in such numbers, that, comparatively speaking, few were left on the seaboard. A large portion of the men who had been engaged in daily work, had enlisted as soldiers, and had marched under the banners of the nation to the defense of its rights--yet amidst the scarcity of hands, a sufficient number were procured for the purpose which the Commissioners had in charge. An increase of wages was the chief impediment, and this they were enabled practically to overcome.

By the exemplary combination of diligence and skill, on the part of the Engineer and Constructors, the business was so accelerated, that the vessel was launched on the twenty-ninth day of October, amidst the plaudits of an unusual number of citizens.

Measures were immediately taken to complete her equipment; the boiler, the engine, and the machinery were put on board with all possible expedition. Their weight and size far surpassed any thing that had been witnessed before among us.

The stores of artillery in New York not furnishing the number and kind of cannon which she was destined to carry, it became necessary to transport guns from Philadelphia. A prize, taken from the enemy, put some fit and excellent pieces at the disposal of the Navy Department. To avoid the danger of capture by the enemy's cruisers, these were carted over the miry roads of New Jersey. Twenty heavy cannon were thus conveyed by the strength of horses. Carriages of the most approved model were constructed, and every thing done to bring her into prompt action, as an efficient instrument of war.

About this time, an officer, pre-eminent for bravery and discipline, was commissioned by the government to her command. Prior to this event, it had been intended by the Commissioners to finish her conformably to the plan originally submitted to the Executive. She is a structure resting upon two boats and keels, separated from end to end by a canal fifteen feet wide, and sixty-six long. One boat contained the caldrons of copper to prepare her steam. The vast cylinder of iron, with its piston, levers, and wheels, occupied a part of its fellow; the great water-wheel revolved in the space between them; the main or gun-deck supported her armament, and was protected by a bulwark four feet ten inches thick, of solid timber. This was pierced by thirty port-holes, to enable as many thirty-two pounders to fire red hot balls; her upper or spar deck was plain, and she was to be propelled by her enginery alone.

It was the opinion of Captain Porter and Mr. Fulton, that the upper deck ought to be surrounded with a bulwark and stanchions--that two stout masts should be erected to support latteen sails--that there should be bowsprits for jibs, and that she should be rigged in a corresponding style. Under authorities so great, and with the expectation of being able to raise the blockade of New London, by destroying, taking, or routing the enemy's ships, all these additions were adopted and incorporated with the vessel.

It must here be observed, that during the exhaustion of the treasury, and the temporary depression of public credit, the Commissioners were exceedingly embarrassed--their payments were made in treasury notes, which they were positively instructed to negotiate at par. On several occasions even these were so long withheld, that the persons who had advanced materials and labor were importunate for payment, and silently discontented. To a certain extent, the Commissioners pledged their private credit. Notwithstanding all this, the men, at one time, actually broke off. The work was retarded, and her completion unavoidably deferred, to the great disappointment of the Commissioners, until winter rendered it impossible for her to act.

Under all this pressure, they, nevertheless, persevered in the important object confided to them. But their exertions were further retarded by the premature and unexpected death of the Engineer. The world was deprived of his invaluable labors before he had completed this favorite undertaking. They will not inquire, wherefore, in the dispensations of Divine Providence, he was not permitted to realize his grand conception. _His discoveries, however, survive for the benefit of mankind_, and will extend to unborn generations.

At length all matters were ready for a trial of the machinery to urge such a bulky vessel through the water. This essay was made on the first day of June, eighteen hundred and fifteen. She proved herself capable of opposing the wind, and of stemming the tide, of crossing currents, and of being steered among vessels riding at anchor, though the weather was boisterous and the water rough. Her performance demonstrated that the project was successful--no doubt remained that a floating battery, composed of heavy artillery, could be moved by steam. The Commissioners returned from the exercise of the day, satisfied that the vessel would answer the intended purpose, and consoled themselves that their care had been bestowed upon a worthy object.

But it was discovered, that various alterations were necessary. Guided by the light of experience, they caused some errors to be corrected, and some defects to be supplied. She was prepared for a second voyage with all practicable speed.

On the fourth of July she was again put in action. She performed a trip to the ocean, eastward of Sandy Hook, and back again, a distance of fifty-three miles, in eight hours and twenty minutes. A part of this time she had the tide against her, and had no assistance whatever from sails. Of the gentlemen who formed the company invited to witness the experiment, not one entertained a doubt of her fitness for the intended purpose.

Additional expedients were, notwithstanding, necessary to be sought for quickening and directing her motion. These were devised and executed with all possible care.

Suitable arrangements having been made, a third trial of her powers was attempted on the eleventh day of September, with the weight of twenty-six of her long and ponderous guns, and a considerable quantity of ammunition and stores on board; her draft of water was short of eleven feet. She changed her course by inverting the motion of the wheel, without the necessity of putting about. She fired salutes as she passed the forts, and she overcame the resistance of the wind and tide in her progress down the bay. She performed beautiful man[oe]uvres around the United States' Frigate JAVA, then at anchor near the light-house. She moved with remarkable celerity, and she was perfectly obedient to her double helm. It was observed that the explosion of powder produced very little concussion. The machinery was not affected by it in the smallest degree. Her progress, during the firing, was steady and uninterrupted. On the most accurate calculations, derived from heaving the log, her average velocity was five and a-half miles per hour. Notwithstanding the resistance of currents, she was found to make headway at the rate of two miles an hour against the ebb of the East River, running three and a-half knots. The day's exercise was satisfactory to the respectable company who attended, beyond their utmost expectations. It was universally agreed that we now possessed a new auxiliary against every maratime invader. The City of New York, exposed as it is, was considered as having the means of rendering itself invulnerable. The Delaware, Chesapeake, Long Island Sound, and every other bay and harbor in the nation, may be protected by the same tremendous power.

Among the inconveniences observable during the experiment, was the heat endured by the men who attended the fires. To enable a correct judgment to be formed on this point, one of the Commissioners (Dr. Mitchel) descended and examined, by a thermometer, the temperature of the hold, between the two boilers. The quicksilver, exposed to the radiant heat of the burning fuel, rose to one hundred and sixteen degrees of Fahrenheit's scale. Though exposed thus to its intensity, he experienced no indisposition afterwards. The analogy of potteries, forges, glass-houses, kitchens, and other places, where laborers are habitually exposed to high heats, is familiar to persons of business and of reflection. In all such occupations, the men, by proper relays, perform their services perfectly well.

The Government, however, will understand that the hold of the present vessel could be rendered cooler by other apertures for the admission of air, and that on building another steam frigate, the comfort of the firemen might be provided for, as in the ordinary steamboats.

The Commissioners congratulate the Government and the nation on the event of this noble project. Honorable alike, to its author and its patrons, it constitutes an era in warfare and the arts. The arrival of peace, indeed, has disappointed the expectations of conducting her to battle. That last and conclusive act of showing her superiority in combat, has not been in the power of the Commissioners to make.

If a continuance of tranquillity should be our lot, and this steam vessel of war be not required for the public defense, the nation may rejoice that the fact we have ascertained is of incalculably greater value than the expenditure--and that if the present structure should perish, we have the information never to perish, how, on a future emergency, others may be built. The requisite variations will be dictated by circumstances.

Owing to the cessation of hostilities, it has been deemed inexpedient to finish and equip her as for immediate and active employ. In a few weeks every thing that is incomplete could receive the proper adjustment.

After so much has been done, and with such encouraging results, it becomes the Commissioners to recommend that the steam frigate be officered and manned for discipline and practice. A discreet commander, with a selected crew, could acquire experience in the mode of navigating this peculiar vessel. The supplies of fuel, the tending of the fire, the replenishing of the expended water, the management of the mechanism, the heating of shot, the exercise of the guns, and various matters, can only become familiar by use. It is highly important that a portion of seamen and marines should be versed in the order and economy of the steam frigate. They will augment, diffuse, and perpetuate knowledge. When, in process of time, another war shall call for more structures of this kind, men, regularly trained to her tactics, may be dispatched to the several stations where they may be wanted. If, on any such disposition, the Government should desire a good and faithful agent, the Commissioners recommend Captain Obed Smith to notice, as a person who has ably performed the duties of inspector from the beginning to the end of the concern.

Annexed to the report, you will find, Sir, several statements explanatory of the subject. A separate report of our colleague, the honorable Oliver Wolcott, whose removal from New York precluded him from attending to the latter part of the business, with his accustomed zeal and fidelity, is herewith presented. A drawing of her form and appearance, by Mr. Morgan, as being like to give satisfaction to the department, is also subjoined, as are likewise an inventory of her furniture and effects, and an account of the timber and metals consolidated in her fabric.

It is hoped these communications will evince the pains taken by the Commissioners, to execute the honorable and responsible trust reposed in them by the Government.

SAMUEL L. MITCHEL. THOMAS MORRIS. HENRY RUTGERS.

* * * * *

FOOTNOTES

[1] _The American Neptune_ (1946), vol. 6, pp. 253-274.

[2] _The American Neptune_ (1944), vol. 4, pp. 327-329.

[3] New York, 1853, pp. 13-17.

[4] Pittsburgh, 1896, pp. 8-16.

[5] See pages 172 through 176 for this report, which is reproduced from CHARLES B. STUART, _Naval and Mail Steamers of the United States_ (New York, 1853), app., pp. 155-159.

[6] National Archives, Navy Records Plans, 80-7-14; and HOWARD I. CHAPELLE, _History of the American Sailing Navy_ (New York: W. W. Norton & Co., 1949), pp. 293-295.

[7] National Archives, Navy Records Plans, 80-7-9; and CHAPELLE, _History of the American Sailing Navy_, pp. 226, 228.

[8] National Archives, Navy Records Plans, 80-7-15.

[9] National Archives, Naval Records Collection, Miscellaneous Letters, 1819, II.

[10] See p. 169, reproduced from CHARLES B. STUART, _Naval and Mail Steamers of the United States_ (New York, 1853), p. 15.

[11] JEAN BAPTISTE MARESTIER, _Mémoire sur les bateaux à vapeur des États-Unis d'Amérique, avec un appendice sur diverses machines relatives à la Marine_ (Paris: L'imprimerie Royal, 1824).

[12] 1820-1823, vol. 7, p. 437.

[13] _Annales de l'industrie nationale et étrangère, ou Mercure Technologique_ (Paris, 1822), pp. 760-762.

[14] January 27, 1823, vol. 7, pp. 436-438.

[15] January-March 1935, vol. 61, pp. 322-328.

[16] HOWARD I. CHAPELLE, _American Small Sailing Craft_ (New York: W. W. Norton & Co., Inc., 1951), pp. 29, 31.

[17] Newport News, Va.: The Mariners' Museum, 1937, p. 23.

[18] Indianapolis, Ind.: Bobbs Merrill, 1932, p. 291.

[19] HENRY WILLIAM EDWARD, _The Double Bottom or Twin Hulled Ship of Sir William Petty_ (Oxford: The Roxburghe Club, 1931).

[20] Publication No. 5 (Newport News: The Mariners' Museum, 1939), p. 22.

* * * * *

Typographical Corrections

Pg. 152: "the _Simon & Jude_, later called _Invention I_" (was "latter").

* * * * *

CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY:

PAPER 40

HISTORY OF PHOSPHORUS

_Eduard Farber_

THE ELEMENT FROM ANIMALS AND PLANTS 178

EARLY USES 181

CHEMICAL CONSTITUTION OF PHOSPHORIC ACIDS 182

PHOSPHATES AS PLANT NUTRIENTS 185

FROM INORGANIC TO ORGANIC PHOSPHATES 187

PHOSPHATIDES AND PHOSPHAGENS 189

NUCLEIN AND NUCLEIC ACIDS 192

PHOSPHATES IN BIOLOGICAL PROCESSES 197

MEDICINES AND POISONS 198

_Eduard Farber_

HISTORY OF PHOSPHORUS

_The "cold light" produced by phosphorus caused it to be considered a miraculous chemical for a long time after its discovery, about 1669. During the intervening three centuries numerous other chemical miracles have been found, yet phosphorus retains a special aura of universal importance in chemistry. Many investigators have occupied themselves with this element and its diverse chemical compounds. Further enlightenment and insight into the ways of nature can be expected from these efforts._

_Not only is the story of phosphorus a major drama in the history of chemistry; it also illustrates, in a spectacular example, the growth of this science through the discovery of connections between apparently unrelated phenomena, and the continuous interplay between basic science and the search for practical usage._

THE AUTHOR: _Eduard Farber is a research professor at American University, Washington, D.C., and has been associated with the Smithsonian Institution as a consultant in chemistry._

When phosphorus was discovered, nearly three centuries ago, it was considered a miraculous thing. The only event that provoked a similar emotion was the discovery of radium more than two centuries later. The excitement about the _Phosphorus igneus_, Boyle's _Icy Noctiluca_, was slowly replaced by, or converted into, chemical research. Yet, if we would allow room for emotion in research, we could still be excited about the wondrous substance that chemical and biological work continues to reveal as vitally important. It is a fundamental plant nutrient, an essential part in nerve and brain substance, a decisive factor in muscle action and cell growth, and also a component in fast-acting, powerful poisons. The importance of phosphorus was gradually recognized and the means by which this took place are characteristic and similar to other developments in the history of science. This paper was written in order to summarize these various means which led to the highly complex ways of present research.

The Element from Animals and Plants

It was a little late to search for the philosophers' stone in 1669, yet it was in such a search that phosphorus was discovered. Wilhelm Homberg (1652-1715) described it in the following manner: Brand, "a man little known, of low birth, with a bizarre and mysterious nature in all he did, found this luminous matter while searching for something else. He was a glassmaker by profession, but he had abandoned it in order to be free for the pursuit of the philosophical stone with which he was engrossed. Having put it into his mind that the secret of the philosophical stone consisted in the preparation of urine, this man worked in all kinds of manners and for a very long time without finding anything. Finally, in the year 1669, after a strong distillation of urine, he found in the recipient a luminant matter that has since been called phosphorus. He showed it to some of his friends, among them Mister Kunkel [sic]."[1]

Neither the name nor the phenomenon were really new. Organic phosphorescent materials were known to Aristotle, and a lithophosphorus was the subject of a book published in 1640, based on a discovery made by a shoemaker, Vicenzo Casciarolo, on a mountain-side near Bologna in 1630.[2] Was the substance new which Brand showed to his friends? Johann Gottfried Leonhardi quotes a book of 1689 in which the author, Kletwich, claims that this phosphorus had already been known to Fernelius, the court physician of King Henri II of France (1154-1189).[3] To the same period belongs the "Ordinatio Alchid Bechil Saraceni philosophi," in which Ferdinand Hoefer found a distillation of urine with clay and carbonaceous material described, and the resulting product named escarbuncle.[4] It would be worth looking for this source; although Bechil would still remain an entirely unsuccessful predecessor, it does seem strange that in all the distillations of arbitrary mixtures, the conditions should never before 1669 have been right for the formation and the observation of phosphorus.

For Brand's contemporaries at least, the discovery was new and exciting. The philosopher Gottfried Wilhelm von Leibniz (1646-1716) considered it important enough to devote some of his time (between his work as librarian in Hanover and Wolfenbüttel, his efforts to reunite the Protestant and the Catholic churches, and his duties as Privy Councellor in what we would call a Department of Justice) to a history of phosphorus. This friend of Huygens and Boyle tried to prove that Kunckel was not justified in claiming the discovery for himself.[5] Since then, it has been shown that Johann Kunckel (1630-1703) actually worked out the method which neither Brand nor his friend Kraft wanted to disclose. Boyle also developed a method independently, published it, and instructed Gottfried Hankwitz in the technique. Later on, Jean Hellot (1685-1765) gave a meticulous description of the details and a long survey of the literature.[6]

To obtain phosphorus, a good proportion of coal (regarded as a type of phlogiston) was added to urine, previously thickened by evaporation and preferably after putrefaction, and the mixture was heated to the highest attainable temperature. It was obvious that phlogiston entered into the composition of the distillation product. The question remained whether this product was generated _de novo_. In his research of 1743 to 1746, Andreas Sigismund Marggraf (1709-1782) provided the answer. He found the new substance in edible plant seeds, and he concluded that it enters the human system through the plant food, to be excreted later in the urine. He did not convince all the chemists with his reasoning. In 1789, Macquer wrote: "There are some who, even at this time, hold that the phosphorical ('phosphorische') acid generates itself in the animals and who consider this to be the 'animalistic acid.'"[7]

Although Marggraf was more advanced in his arguments than these chemists, yet he was a child of his time. The luminescent and combustible, almost wax-like substance impressed him greatly. "My thoughts about the unexpected generation of light and fire out of water, fine earth, and phlogiston I reserve to describe at a later time." These thoughts went so far as to connect the new marvel with alchemical wonder tales. When Marggraf used the "essential salt of urine," also called _sal microcosmicum_, and admixed silver chloride ("horny silver") to it for the distillation of phosphorus, he expected "a partial conversion of silver by phlogiston and the added fine vitrifiable earth, but no trace of a more noble metal appeared."[8]

Robert Boyle had already found that the burning of phosphorus produced an acid. He identified it by taste and by its influence on colored plant extracts serving as "indicators." Hankwitz[9] described methods for obtaining this acid, and Marggraf showed its chemical peculiarities. They did not necessarily establish phosphorus as a new element. To do that was not as important, at that time, as to conjecture on analogies with known substances. Underlying all its unique characteristics was the analogy of phosphorus with sulfur. Like sulfur, phosphorus can burn in two different ways, either slowly or more violently, and form two different acids. The analogy can, therefore, be extended to explain the results in both groups in the same way. In the process of burning, the combustible component is removed, and the acid originally combined with the combustible is set free. Whether the analogy should be pursued even further remained doubtful, although some suspicion lingered on for a while that phosphoric acid might actually be a modified sulfuric acid. Analogies and suspicions like these were needed to formulate new questions and stimulate new experiments. They are cited here for their important positive value in the historical development, and not for the purpose of showing how wrong these chemists were from our point of view, a point of view which they helped to create.

The widespread interest in the burning of sulfur and of phosphorus, naturally, caught Lavoisier's attention. In his first volume of _Opuscules Physiques et Chimiques_ (1774), he devoted 20 pages to his experiments on phosphorus. He amplified them a few years later[10] when he attributed the combustion to a combination of phosphorus with the "eminently respirable" part of air. In the _Méthode de Nomenclature Chimique_ of 1787, the column of "undecomposed substances" lists sulfur as the "radical sulfurique," and phosphorus, correspondingly, as the "radical phosphorique." The acids are now shown to be compounds of the "undecomposed" radicals, the complete reversion of the previous concept of this relationship. A part of the old analogy remained as far as the acids are concerned: sulfuric acid corresponds to phosphoric; sulfurous acid to phosphorous acid with less oxygen than in the former.[11]

Early Uses

In the 18th century, phosphorus was a costly material. It was produced mostly for display and to satisfy curiosity. Guillaume François Rouelle (1703-1770) demonstrated the process in his lectures, and, as Macquer reports, he "very often" succeeded in making it.[12] Robert Boyle had the idea of using phosphorus as a light for underwater divers.[13] A century later, "instant lights" were sold, with molten phosphorus as the "igniter," but they proved cumbersome and unreliable.[14] Because white phosphorus is highly poisonous, an active development of the use in matches occurred only after the conversion of the white modification into the red had been studied by Émile Kopp (1844), by Wilhelm Hittorf (1824-1914) and, in its practical application, by Anton Schrötter (1802-1875).[15]

The most exciting early use, however, was in medicine. It is not surprising that such a use was sought at that time. Any new material immediately became the hope of ailing mankind--and of striving inventors.[16] Phosphorus was prescribed, in liniments with fatty oils or as solution in alcohol and ether, for external and internal application. A certain Dr. Kramer found it efficient against epilepsy and melancholia (1730). A Professor Hartmann recommended it against cramps.[17] However, in the growing production of phosphorus for matches, the workers experienced the poisonous effects. In the plant of Black and Bell at Stratford, this was prevented by inhaling turpentine. Experiments on dogs were carried out to show that poisoning by phosphorus could be remedied through oil of turpentine.[18]

Chemical Constitution of Phosphoric Acids

In a long article on phosphorus, Edmond Willm wrote in 1876: "For a century, urine was the only source from which phosphorus was obtained. After Gahn, in 1769, recognized the presence of phosphoric acid in bones, Scheele indicated the procedure for making phosphorus from them."[19] Actually, Gahn used at first hartshorn (_Cornu cervi ustum_), and Scheele doubted, until he checked it himself, that his esteemed friend was right. A few years later, Scheele corrected Gahn's assumption that the _sal microcosmicum_ was an ammonia salt; instead, it is "a tertiary neutral salt, consisting of _alkali minerali fixo_ (i.e., sodium), _alkali volatili_, and _acido phosphori_."[20]

In the years after 1770, phosphorus was discovered in bones and many other parts of various animals. Treatment with sulfuric acid decomposed these materials into a solid residue and dissolved phosphoric acid. Many salts of this acid were produced in crystalline form. Heat resistance had been considered one of the outstanding characteristics of phosphoric acid. Now, however, in the processes of drying and heating certain phosphates, it became clear that three kinds of phosphoric acids could be produced: _ortho_, _pyro_, and _meta_.

Berzelius cited these acids as examples of compounds which are ISOMERIC. This word was intended to designate compounds which contain the same number of atoms of the same elements but combined in different manners, thereby explaining their different chemical properties and crystal forms. It was in 1830 that Berzelius propounded this companion of the concept, ISOMORPHISM, which was to collect all cases of equal crystal form in compounds in which equal numbers of atoms of different elements are put together in the same manner. Together, the two concepts of isomerism and isomorphism seemed to cover all the known exceptions from the simplest assumption as to specificity and chemical composition.

However, only a few years later Thomas Graham (1805-1869) proved that the three phosphoric acids are not isomeric. He used the proportion of 2 P to 5 O in the oxide which Berzelius had thought justified at least until "an example of the contrary could be sufficiently established."[21] Refining the techniques of Gay-Lussac (1816) and several other investigators, Graham characterized the three phosphoric acids as "a terphosphate, a biphosphate, and phosphate of water." Actually, this was the wrong terminology for what he meant and formulated as trihydrate, bihydrate, and monohydrate of phosphorus oxide. In his manner of writing the formulas, each dot over the symbol for the element was to indicate an atom of oxygen; thus, he wrote:

... :: .. ... . . H^{3} P H^{2} P and H P.[22]

Graham had come to this understanding of the phosphoric acids through his previous studies of "Alcoates, definite compounds of Salts and Alcohol analogous to the Hydrates" (1831). Liebig started from analogies he saw with certain organic acids when he formulated the phosphoric acids with a constant proportion of water (aq.) and varying proportions of "phosphoric acid" (P) as follows:

2 P 3 aq. phosphoric acid 3 P 3 aq. pyrophosphoric acid 6 P 3 aq. metaphosphoric acid.

Salts are formed when a "basis," i.e., a metal oxide, replaces water. When potassium-acid sulfate is neutralized by sodium base, the acid-salt divides into Glauber's salt and potassium sulfate, which proves the acid-salt to be a mixture of the neutral salt with its acid. Sodium-acid phosphate behaves quite differently. After neutralization by a potassium "base" (hydroxide), the salt does not split up; a uniform sodium-potassium phosphate is obtained. Therefore, phosphoric acid is truly three-basic![23]

This result has later been confirmed, but the analogy by means of which it had been obtained was very weak, in certain parts quite wrong.

The acids from the two lower oxides of phosphorus were also considered as three-basic. Adolphe Wurtz (1817-1884) formulated them in 1846, according to the theory of chemical types:

(PO)··· O^{3} phosphoric acid H^{3}

(PHO)·· O^{2} phosphorus acid H^{2}

(PH^{2}O)· O hypophosphorous acid.[24] H

Further proof for these constitutions was sought in the study of the esters formed when the acids react with alcohols.

Among the analogies and generalizations by which the research on phosphoric acid was supported, and to the results of which it contributed a full share, was the new theory of acids. Not oxygen, Lavoisier's general acidifier, but reactive hydrogen determines the character of acids. In this brief survey, it seems sufficient just to mention this connection without describing it in detail.

The study of phosphoric acids led to important new concepts in theoretical chemistry. The finding of polybasicity was extended to other acids and formed the model that helped to recognize the polyfunctionality in other compounds, like alcohols and amines. The hydrogen theory of acids was fundamental for further advance. In another dimension, it is particularly interesting to see that large-scale applications followed almost immediately and directly from the new theoretical insight. The first and foremost of these applications was in agriculture.

Phosphates as Plant Nutrients

One hundred years after the discovery of "cold light," the presence of phosphorus in plants and animals was ascertained, and its form was established as a compound of phosphoric acid. This knowledge had little practical effect until the "nature" of the acid, in its various forms, was explained through the work of Thomas Graham. From it, there started a considerable technical development.

At about that time (1833), the Duke of Richmond proved that the fertilizing value of bones resided not in the gelatin, nor in the calcium, but in the phosphoric acid. Thus, he confirmed what Théodore de Saussure had said in 1804, that "we have no reason to believe" that plants can exist without phosphorus. Unknowingly at first, the farmer had supplied this element by means of the organic fertilizers he used: manure, excrements, bones, and horns. Now, with the value of phosphorus known, a search began for mineral phosphates to be applied as fertilizers. Jean Baptiste Boussingault (1802-1887), an agricultural chemist in Lyons, traveled to Peru to see the guano deposits. Garcilaso de la Vega (ca. 1540 to ca. 1616) noted in his history of Peru (1604) that guano was used by the Incas as a fertilizer. Two hundred years later, Alexander von Humboldt revived this knowledge, and Humphry Davy wrote about the benefits of guano to the soil. Yet, the application of this fertilizer developed only slowly, until Justus Liebig sang its praise. Imports into England rose and far exceeded those into France where, between 1857 and 1867, about 50,000 tons were annually received.

The other great advance in the use of phosphatic plant nutrients started with Liebig's recommendation (1840) to treat bones with sulfuric acid for solubilization. This idea was not entirely new; since 1832, a production of a "superphosphate" from bones and sulfuric acid had been in progress at Prague. At Rothamsted in 1842, John Bennet Lawes obtained a patent on the manufacture of superphosphate. Other manufactures in England followed and were successful, although James Muspratt (1793-1886) at Newton lost much time and "some thousands of pounds" on Liebig's idea of a "mineral manure."

It was difficult enough to establish the efficacy of bones and artificially produced phosphates in promoting the growth of plants under special conditions of soils and climate; therefore, the question as to the action of phosphates in the growing plant was not even seriously formulated at that time. The beneficial effects were obvious enough to increase the use of phosphates as plant nutrients and to call for new sources of supply. Active developments of phosphate mining and treating started in South Carolina in 1867, and in Florida in 1888.[25]

In a reciprocal action, more phosphate application to soils stimulated increasing research on the conditions and reactions obtaining in the complex and varying compositions called soil. The findings of bacteriologists made it clear that physics and chemistry had to be amplified by biology for a real understanding of fertilizer effects. After 1900, for example, Julius Stoklasa (1857-1936) pointed out that bacterial action in soil solubilizes water-insoluble phosphates and makes them available to the plants.[26]

The insight into the importance of phosphorus in organisms, especially since Liebig's time, is reflected in the work of Friedrich Nietzsche (1844-1900). This "re-valuator of all values" who modestly said of himself: "I am dynamite!" once explained the human temperaments as caused by the inorganic salts they contain: "The differences in temperament are perhaps caused more by the different distribution and quantities of the inorganic salts than by everything else. Bilious people have too little sodium sulfate, the melancholics are lacking in potassium sulfate and phosphate; too little calcium phosphate in the phlegmatics. Courageous natures have an excess of iron phosphate." (See