Chapter 1

Produced by Olaf Voss, Don Kretz, Juliet Sutherland, Charles Franks and the Online Distributed Proofreaders Team

SCIENTIFIC AMERICAN SUPPLEMENT NO. 430

NEW YORK, MARCH 29, 1884

Scientific American Supplement. Vol. XVII, No. 430.

Scientific American established 1845

Scientific American Supplement, $5 a year.

Scientific American and Supplement, $7 a year.

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TABLE OF CONTENTS.

I. ENGINEERING, MECHANICS, ETC.--The Iron Industry In Brazil.--By Prof. P. FEHRAND.--Methods of obtaining iron.--Operation of the system.--Elaboration of the ore.--Setting up a forge.-- Selling price of iron

The Steamer Churchill, built by Messrs. Hall, Russell & Co., for service at Natal.--With full page of illustrations

Three-Way Tunnels

Falconetti's Continuously Primed Siphon.--Manner of carrying a water course over a canal, river, or road.--With engraving

The Weibel-Piccard System of Evaporating Liquids.-- 2 illustrations

II. TECHNOLOGY.--Coal Gas as a Labor--saving Agent in Mechanical Trades.--By T. FLETCHER.--Gas as fuel.--Arrangement of burners for disinfection, for drying glue, albumen, etc.--Best burners. --Gas bars for furnaces, etc.

Instantaneous Photography.--Several illustrations

III. ELECTRICITY, MAGNETISM, ETC.--Electric Launches.--A paper read before the Society of Arts by A. RECKENZAUN, and discussion on the same.--Advantages of electromotive power.-- Cost of same.--Experimental electric launches

First Experiments with the Electric Light.--Sir Humphry Davy's experiments in 1813,--With two engravings

Electrical Grapnel for Submarine Cables and Torpedo Lines.-- 3 figures

Hughes' New Magnetic Balance.--1 figure

Apparatus for Measuring Small Resistances.--With engraving and diagram

Terrestrial Magnetism.--Magnetism on railways.--Synchronous Seismology

IV. ARCHITECTURE.--Adornments of the New Post Office at Leipzig.-- 2 engravings

V. NATURAL HISTORY, ETC.--Comparison of Strength of Large and Small Animals.--By W. N. LOCKINGTON

Oil in California

VI. HORTICULTURE, BOTANY. ETC.--The Dodder.--A new parasitic plant.--With engraving

Recent Botanical Investigations

VII. MEDICINE, HYGIENE ETC.--Nutritive Value of Condiments.--By H. D. ABBOTT

VIII. MISCELLANEOUS.--Mont St. Michel, Normandy.--With engraving

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THE DODDER.

The genus _Cuscuta_ contains quite a number of species which go under the common name of dodder, and which have the peculiarily of living as parasites upon other plants. Their habits are unfortunately too well known to cultivators, who justly dread their incursions among cultivated plants like flax, hops, etc.

All parasitic plants, or at least the majority of them, have one character in common which distinguishes them at first sight. In many cases green matter is wanting in their tissues or is hidden by a livid tint that strikes the observer. Such are the Orobanchaccæ, or "broomropes," and the tropical Balanophoraceæ. Nevertheless, other parasites, such as the mistletoe, have perfectly green leaves.

However this may be, the naturalist's attention is attracted every time he finds a plant deprived of chlorophyl, and one in which the leaves seem to be wanting, as in the dodder that occupies us. In fact, as the majority of parasites take their nourishment at the expense of the plants upon which they fasten themselves, they have no need, as a general thing, of elaborating through their foliar organs the materials that their hosts derive from the air; in a word, they do not breathe actively like the latter, since they find the elements of their nutrition already prepared in the sap of their nurses. The dodders, then, are essentially parasites, and their apparent simplicity gives them a very peculiar aspect. Their leaves are wholly wanting, or are indicated by small, imperceptible scales, and their organs of vegetation are reduced to a stem and filiform branches that have obtained for them the names of _Cheveux de Venus_ (Venus' Hair) and _Cheveux du Diable_ (devil's hair) in French, and gold thread in English. Because of their destructive nature they have likewise been called by the unpoetic name of hellweed; and, for the reason that they embrace their host plants so closely, they have been called love weed and love vine.

When a seed of _Cuscuta_, germinates, no cotyledons are to be distinguished. This peculiarity, however, the plant has in common with other parasites, and even with some plants, such as orchids, that vegetate normally. The radicle of the dodder fixes itself in the earth, and the little stem rises as in other dicotyledons; but soon (for the plantlet could not live long thus) this stem, which is as slender as a thread, seeks support upon some neighboring plant, and produces upon its surfaces of contact one or more little protuberances that shortly afterward adhere firmly to the support and take on the appearance and functions of cupping glasses. At this point there forms a prolongation of the tissue of the dodder--a sort of cone, which penetrates the stalk of the host plant. After this, through the increase of the stem and branches of the parasite, the supporting plant becomes interlaced on every side, and, if it does not die from the embraces of its enemy, its existence is notably hazarded. It is possible for a _Cuscuta_ plant to work destruction over a space two meters in diameter in a lucern or clover field; so, should a hundred seeds germinate in an acre, it may be easily seen how disastrous the effects of the scourge would prove.

These enemies of our agriculture were scarcely to be regarded as injurious not very many years ago, for the reason that their sources of development were wanting. Lucern and clover are comparatively recent introductions into France, at least as forage plants. Other cultures are often sorely tried by the dodder, and what is peculiar is that there are almost always species that are special to such or such a plant, so that the botanist usually knows beforehand how to determine the parasite whose presence is made known to him. Thus, the _Cuscuta_ of flax, called by the French _Bourreau du Lin_ (the flax's executioner), and by the English, flax dodder, grows only upon this textile plant, the crop of which it often ruins. On account of this, botanists call this species Cuscuta epilinum. Others, such as C. Europæa, attack by preference hemp and nettle. Finally, certain species are unfortunately indifferent and take possession of any plant that will nourish them. Of this number is the one that we are about to speak of.

Attempts have sometimes been made out of curiosity to cultivate exotic species. One of the head gardeners at the Paris Museum received specimens of _Cuscuta reflexa_ from India about two years ago, and, having placed it upon a geranium plant, succeeded in cultivating it. Since then, other plants have been selected, and the parasite has been found to develop upon all of them. What adds interest to this species is that its flowers are relatively larger and that they emit a pleasant odor of hawthorn. Mr. Hamelin thinks that by reason of these advantages, an ornamental plant might be made of it, or at least a plant that would be sought by lovers of novelties. Like the majority of dodders, this species is an annual, so that, as soon as the cycle of vegetation is accomplished, the plant dies after flowering and fruiting. But here the seeds do not arrive at maturity, and the plant has to be propagated by a peculiar method. At the moment when vegetation is active, it is only necessary to take a bit of the stem, and then, after previously lifting a piece of the bark of the plant upon which it is to be placed, to apply this fragment of _Cuscuta_ thereto (as in grafting), place the bark over it, and bind a ligature round the whole. In a short time the graft will bud, and in a few months the host plant will be covered with it.

The genus _Cuscuta_ embraces more than eighty species, which are distributed throughout the entire world, but which are not so abundant in cold as in warm regions.--_La Nature_.

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RECENT BOTANICAL INVESTIGATIONS.

It is commonly said that there is a great difference between the transpiration and evaporation of water in plants. The former takes place in an atmosphere saturated with moisture, it is influenced by light, by an equable temperature, while evaporation ceases in a saturated atmosphere. M. Leclerc has very carefully examined this question, and he concludes that transpiration is only the simple evaporation of water. If transpiration is more active in the plant exposed to the sun, that is due to the heat rays, and in addition arises in part from the fact that the assimilating action of chlorophyl heats the tissues, which in turn raises the temperature and facilitates evaporation.

As to transpiration taking place in a saturated atmosphere, it is a mistake; generally there is a difference in the temperature of the plant and the air, and the air is not saturated in its vicinity. In a word, transpiration and evaporation is the same thing.

Herr Reinke has made an interesting examination of the action of light on a plant. He has permitted a pencil of sun rays to pass through a converging lens upon a cell containing a fragment of an aquatic plant. He was enabled to increase the intensity of the light, so that it should be stronger or weaker than the direct sunlight. He could thus vary its intensity from 1/16 of that of direct sunlight to an intensity 64 times stronger. The temperature was maintained constant.

Herr Reinke has shown that the chlorophyl action increases regularly with the light for intensities under that of direct sunlight; but what is unexpected, that for the higher intensities above that of ordinary daylight the disengagement of oxygen remains constant.

M. Leclerc du Sablon has published some of his results in his work on the opening of fruits. The influences which act upon fruit are external and internal. The external cause of dehiscence is drying. We can open or shut a fruit by drying or wetting it. The internal causes are related to the arrangement of the tissues, and we may say that the opening of fruit can be easily explained by the contraction of the ligneous fibers under drying influences. M. Leclerc shows by experiment that the fibers contract more transversely than longitudinally, and that the thicker fibers contract the most. This he finds is connected with the opening of dry fruits.

Herr Hoffman has recently made some interesting experiments upon the cultivation of fruits.

It is well known that many plants appear to select certain mineral soils and avoid others, that a number of plants which prefer calcareous soils are grouped together as _calcicoles_, and others which shun such ground as _calcifuges_. Herr Hoffman has grown the specimen which has been cited by many authors as absolutely calcifugic. He has obtained strong plants upon a soil with 53 per cent. of lime, and these have withstood the severe winter of 1879-1880, while individuals of the same species grown on silicious ground have failed. This will modify the ideas of agriculturists, at least in regard to this plant.

Herr Schwarz has been engaged in the study of the fine hairs of roots. According to this author, there is a maximum and minimum of humidity, between which there lies a mean of moisture, most favorable for the development of these capillary rootlets, and this amount of moisture varies with different plants. He finds that this growth of hair-like roots is conditioned upon the development of the main root from which it springs. In a weak solution of brine these fine roots are suppressed, while the growth of the main root is continued. The changes of the _milieu_ lead to changes in the form of the hairs, rendering them even branched.

Signor Savastano has ventured to criticise as exaggerated the views of Muller, Lubbock, and Allen on the adaptation of flowers to insects, having noticed that bees visit numbers of flowers, and extract their honey without touching the stigmas or pistils. He has also found them neglecting flowers which were rich in honey and visiting others much poorer. These observations have value, but cannot be considered as seriously impairing the multiplied evidences of plant adaptation to insect life.

Mr. Camus has shown that the flora of a small group of hills, the Euganean Mountains, west of the Apennines and south of the Alps, has a peculiar flora, forming an island in the midst of a contrasted flora existing about it. Here are found Alpine, maritime, and exotic plants associated in a common isolation.--_Revue Scientifique_.

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RECENT BOTANICAL ADVANCES.

Among the most significant of the recent discoveries in botany, is that respecting the continuity of the protoplasm from cell to cell, by means of delicate threads which traverse channels through the cell walls. It had long been known, that in the "sieve" tissues of higher plants there was such continuity through the "sieve plates," which imperfectly separated the contiguous cells. This may be readily seen by making longitudinal sections of a fibro-vascular bundle of a pumpkin stem, staining with iodine, and contracting the protoplasm by alcohol. Carefully made specimens of the soft tissues of many plants have shown a similar protoplasmic continuity, where it had previously been unsuspected. Some investigators are now inclined to the opinion that protoplasmic continuity may be of universal occurrence in plants.

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ELECTRIC LAUNCHES.

[Footnote: A recent lecture before the Society of ATM, London.]

By A. RECKENZAUN.

It is not my intention to treat this subject from a shipwright's point of view. The title of this paper is supposed to indicate a mode of propelling boats by means of electrical energy, and it is to this motive power that I shall have the honor of drawing your attention.

The primary object of a launch, in the modern sense of the word, lies in the conveyance of passengers on rivers and lakes, less than for the transport of heavy goods; therefore, it may not be out of place to consider the conveniences arising from the employment of a motive power which promises to become valuable as time and experience advance. In a recent paper before the British Association at Southport, I referred to numerous experiments made with electric launches; now it is proposed to treat this subject in a wider sense, touching upon the points of convenience in the first place; secondly, upon the cost and method of producing the current of electricity; and thirdly, upon the construction and efficiency of the propelling power and its accessories.

Whether it is for business, pleasure, or war purposes a launch should be in readiness at all times, without requiring much preparation or attention. The distances to be traversed are seldom very great, fifty to sixty miles being the average.

Nearly the whole space of a launch should be available for the accommodation of passengers, and this is the case with an electrically propelled launch. We have it on good authority, that an electric launch will accommodate nearly double the number of passengers that a steam launch of the same dimensions would; therefore, for any given accommodation we should require a much smaller vessel, demanding less power to propel it at a given rate of speed, costing less, and affording easier management.

A further convenience arising from electromotive power is the absence of combustibles and the absence of the products of combustion-matters of great importance; and for the milder seasons, when inland navigation is principally enjoyed, the absence of heat, smell, and noise, and, finally, the dispensing with one attendant on board, whose wages, in most cases, amount to as much or more than the cost of fuel, besides the inconvenience of carrying an additional individual.

I do not know whether the cost of motive power is a serious consideration with proprietors of launches, but it is evident that if there be a choice between two methods of equal qualities, the most economical method will gain favor. The motive power on the electric launch is the electric current; we must decide upon the mode of procuring the current. The mode which first suggested itself to Professor Jacobi, in the year 1838, was the primary battery, or the purely chemical process of generating electricity.

Jacobi employed, in the first instance, a Daniell's battery, and in later experiments with his boat on the river Neva, a Grove's battery. The Daniell's battery consisted of 320 cells containing plates of copper and zinc; the speed attained by the boat with this battery did not reach one mile and a quarter per hour; when 64 Grove cells were substituted, the speed came to two and a quarter miles per hour; the boat was 38 feet long. 7½ beam, and 3 feet deep. The electromotor was invented by Professor Jacobi; it virtually consisted of two disks, one of which was stationary, and carried a number of electromagnets, while the other disk was provided with pieces of iron serving as armatures to the pole pieces of the electromagnets, which were attracted while the electric current was alternately conveyed through the bobbins by means of a commutator, producing continuous rotation.

We are not informed as to the length of time the batteries were enabled to supply the motor with sufficient current, but we may infer from the surface of the acting materials in the battery that the run was rather short; the power of the motor was evidently very small, judging by the limited speed obtained, but the originality of Jacobi deserves comment, and for this, as well as for numerous other researches, his name will be remembered at all times.

It may not be generally known that an electric launch was tried for experimental purposes, on a lake at Pentlegaer, near Swansea. Mr. Robert Hunt, in the discussion of his paper on electromagnetism before the Institution of Civil Engineers in 1858, mentioned that he carried on an extended series of experiments at Falmouth, and at the instigation of Benkhausen, Russian Consul-General, he communicated with Jacobi upon the subject. In the year 1848, at a meeting of the British Association at Swansea, Mr. Hunt was applied to, by some gentlemen connected with the copper trade of that part, to make some experiments on the electrical propulsion of vessels; they stated, that although electricity might cost thirty times as much as the power obtained from coal it would, nevertheless, be sufficiently economical to induce its employment for the auxiliary screw ships employed in the copper trade with South America.

The boat at Swansea was partly made under Mr. (now Sir William) Grove's directions, and the engine was worked on the principle of the old toys of Ritchie, which consisted of six radiating poles projecting from a spindle, and rotating between a large electro-magnet. Three persons traveled in Hunt's boat, at the rate of three miles per hour. Eight large Grove's cells were employed, but the expense put it out of question as a practical application.

Had the Gramme or Siemens machine existed at that time, no doubt the subject would have been further advanced, for it was not merely the cost of the battery which stood in the way, but the inefficient motor, which returned only a small fraction of the power furnished by the zinc.

Professor Silvanus Thompson informs us that an electric boat was constructed by Mr. G. E. Dering, in the year 1856, at Messrs. Searle's yard, on the River Thames; it was worked by a motor in which rotation was effected by magnets arranged within coils, like galvanometer needles, and acted on successively by currents from a battery.

From a recent number of the _Annales de l'Electricite_, we learn that Count de Moulins experimented on the lake in the Bois de Boulogne, in the year 1866, with an iron flat-bottomed boat, carrying twelve persons. Twenty Bunsen cells furnished the current to a motor on Froment's principle turning a pair of paddle wheels.

In all these reports there is a lack of data. We are interested to know what power the motors developed, the time and speed, as well as dimensions and weights.

Until Trouve's trip on the Seine, in 1881, and the launch of the Electricity on the Thames, in 1882, very little was known concerning the history of electric navigation.

M. Trouve originally employed Plante's secondary battery, but afterward reverted to a bichromate battery of his own invention. In all the primary batteries hitherto applied with advantage, zinc has been used as the acting material. Where much power is required, the consumption of zinc amounts to a formidable item; it costs, in quantity, about 3d. per pound, and in a well arranged battery a definite quantity of zinc is transformed. The final effect of this transformation manifests itself in electrical energy, amounting to about 746 watts, or one electrical horse power for every two pounds of this metal consumed per hour. The cost of the exciting fluid varies, however, considerably; it may be a solution of salts, or it may be dilute acid. Considering the zinc by itself, the expense for five electrical or four mechanical horse power through an efficient motor, in a small launch, would be 2s. 6d. per hour. Many persons would willingly sacrifice 2s. 6d per hour for the convenience, but a great item connected with the employment of zinc batteries is in the exciting fluid, and the trouble of preparing the zinc plates frequently. The process of cleaning, amalgamating and refilling is so tedious, that the use of primary batteries for locomotive purposes is extremely limited. To recharge a Bunsen, Grove, or bichromate battery, capable of giving six or seven hours' work at the rate of five electrical horse power, would involve a good day's work for one man; no doubt he would consider himself entitled to a full day's wages, with the best appliances to assist him in the operation.

Several improved primary batteries have recently been brought out, which promise economical results. If the residual compound of zinc can be utilized, and sold at a good price, then the cost of such motive power may be reduced in proportion to the value of those by-products.

For the purpose of comparison, let us now employ the man who would otherwise clean and prepare the primary cells, at engine driving. We let him attend to a six horse power steam engine, boiler, and dynamo machine for charging 50 accumulators, each of a capacity of 370 ampere hours, or one horse power hour. The consumption of fuel will probably amount to 40 lb. per hour, which, at the rate of 18s. a ton, will give an expenditure of nearly 4d. per hour. The energy derived from coal in the accumulator costs, in the case of a supply of five electrical horse power for seven hours, 2s. 9d.; the energy derived from the zinc in a primary battery, supplying five electrical horse power for seven hours, would cost 17s. 3d.

It is hardly probable that any one would lay down a complete plant, consisting of a steam or gas engine and dynamo, for the sole purpose of charging the boat cells, unless such a boat were in almost daily use, or unless several boats were to be supplied with electrical power from one station. In order that electric launches may prove useful, it will be desirable that charging stations should be established, and on many of the British and Irish rivers and lakes there is abundance of motive power, in the shape of steam or gas engines, or water-wheels.

A system of hiring accumulators ready for use may, perhaps, best satisfy the conditions imposed in the case of pleasure launches.