Dr. Lardner remarked that the theory of Mr. Russell was quite new to him; but, after the exposition which he had heard, he was satisfied of its accuracy-Mr. Russell observed that there was another important circumstance to which he had not alluded, and in which great advantage might be derived from the application of a high power: thus the owner of a vessel which usually accomplishes her voyage in fifteen days, but, owing to storms or adverse winds, occasionally takes twenty, must so regulate her stated periods of departure as to allow for these adverse circumstances; and four or five such vessels may be required to keep up a regular communication between places for which three or four would be sufficient, if, by increased power, the average voyage were reduced to ten, and the adverse to fourteen days; and thus a large capital would be saved, as well as more voyages accomplished. The principles which he had developed might also, he thought, be applied advantageously under many other circumstances, such as in mines subject to uncertain in-rushings of water, &c. In reply to a question, Mr. Russell stated that his principle was only true in reference to vessels making long voyages, for, where not exposed to adverse contingencies of wind and weather, a greater additional power would be merely an addiditional expense.

On Waves.-Mr. Scott Russell brought up the Report of the Committee (Sir John Robinson and Mr. Russell) on Waves. Since the last meeting (see Mech. Mag. vol. xxix., pp. 410, and 426), the Committee had continued their researches, and had, in each department, confirmed or corrected the results formerly obtained by them, and also extended their acquaintance with several interesting phenomena. The first object of their attention, was the determination of the nature and laws of certain kinds of waves. Of these, the most important species was that called by Mr. Russell the Great Solitary Wave, or the Primary Wave of Translation; the second was the Oscillatory Wave, or secondary species. The recent researches, while they had confirmed and extended to a larger scale the observations of preceding years, have in no respect altered the views formerly stated by this Committee. The form of the wave is that to which the name Hemicycloid has been given; its velocity is that due to half the depth of the fluid, reckoned from the top of the wave to the centre of gravity of the section, where the depth of the channel is not uniform. The motion of the particles, is a motion of permanent translation in the direction of the motion of the wave, through a space equal to double the wave's height; the particles of the water perfectly at rest

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before the approach of the wave were lifted up, translated forwards, and were deposited perfectly at rest in their new locations-the translation taking place equally throughout the whole depth of the fluid. It had been stated by Mr. Russell, in a previous Report, that all the data requisite to derive the phenomena of the great wave of translation had been now obtained, and that he himself had found no difficulty in obtaining the laws of this wave from the equations of M. Laplace, on the hypothesis, that the motion of the water particles was not infinitely small, and the oscillations infinitely small, as had been hitherto supposed, but that they had the magnitude and nature actually found in these experiments. During the past year, considerable progress has been made in this examination, and highly satisfactory confirmations of the truth of these views had been obtained, by the labours of Professor Kelland. had also adopted the method of introducing the hypothesis of the particles of the water having the motions observed in the experiments-viz. a motion of permanent translation in a given course; and although his results did not perfectly accord with the experiments, they had presented a much closer approximation to them than previous investigations, and were to be regarded as additions to the theory of the motion of waves. The second subject of inquiry by this Committee regarded the connection which existed between the motion of waves, and the resistance of fluids to the motion of floating bodies-a subject closely connected with practical navigation. In the continuation of this inquiry, the Committee had received many confirmations of their former views, while they had been tended beyond their former means of observation. The phenomenon of vessels at high velocities riding the wave, had been exhibited to an extent never before witnessed. It had been formerly observed, that when a vessel was, by any means, drawn along the surface of water with a high velocity, it produced a wave, which was a wave of translation, moving with the velocity due to the depth; and that whenever the velocity of the vessel becomes greater than the velocity of the wave, the vessel is carried along on the top of the wave with diminished resistance. This phenomenon had been last year exhibited on a scale much more striking than formerly. The wave, divided in two by the prow of the vessel, had risen on each side to a height far greater than that even of the vessel itself; it expanded on each side of the vessel, from stem to stern, in a broad unbroken sheet of water, bearing along the vessel between what seemed to be a pair of extended gossamer wings, giving, at ex

ex

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tremely high velocities, a resistance very much less than had hitherto been observed. The third point of inquiry concerns both the theory of hydrodynamics, and the art of practical navigation. What is the form of a solid of least resistance, is a question which has been much discussed since the days of Sir Isaac Newton. What is the shape to be given to a vessel or ship, so that it may be driven by sails, or propelled by oars or steam, with the greatest velocity, or at the least expenditure of power? Is the same question asked by the practical shipbuilder, in relation to his art. It had been inferred by Mr. Russell, from certain theoretical considerations, that a certain form, which he called the Wave Form of vessel, would be the form of least resistance, and the form of greatest velocity. This form was, that the lines of anterior displacement should correspond to the outline of the great wave of translation anteriorly, and to the outline of the posterior wave of replacement, towards the stern. This form had been the subject of experiment from 1834 to the present time; and the experiments of last year confirmed the truth of the original supposition, that this form was that of least resistance. A very curious and gratifying confirmation of the truth of the hypothesis had been received during the course of last year.

A clergyman in the north of Scotland the Rev. Mr. Brodie-had seen an account of these experiments in the Reports of the Association, and had deduced from theory, without a knowledge of Mr. Russell's process, results almost precisely the same, so as to give them the most gratifying confirmation, although derived from grounds somewhat different. The views formerly submitted to the Association, on the form of vessel best suited to the practical purposes of navigation, had, during the past year, received very remarkable practical confirmation. A large steam-vessel had been built on the wave principle-a vessel of 660 tons, with an engine of 220 horse power-and it had turned out that this was the fastest vessel now in Great Britain. This vessel, built as a pleasure-yacht, combined the qualities of sailing fast, and carrying a large cargo: she was named the Fire King, and belonged to Mr. Ashton Smith, of Wales. The last point of inquiry in which this Committee had been engaged during the past year, was the question of the nature and laws of the tidal wave, as propagated along our shores, and up the estuaries of our great rivers. But the nature of its propagation along our shores, after it ceased to be affected by the celestial influence, formed a terrestrial mechanism, with which we were still very imperfectly acquainted. To this subject, the

Committee had devoted their attention, and they had made simultaneous observations for this purpose, at thirteen different stations along the Frith of Forth. The Board of Northern Lights, and Mr. Stevenson, their engineer, had afforded every facility for the observations, and results of a very remarkable nature were obtained. It was found that there were four tides a day in the Forth instead of two-four high waters and four low waters. Mr. Russell exhibited drawings of these tidal waves, and gave, what he conceived the explanation of a phenomenon, which is, he thinks, much more common than hitherto supposed. It is well known, that the tidal wave which brings high water from the Atlantic to the south-western shores of Great Britain, becomes divided into two parts, one of which passes upwards through the English Channel, and the other passing round the west and north of Ireland and Great Britains, bring high water to the east coast of Scotland and to the Frith of Forth. Now, it appears not to have been recollected, that the other wave, after coming up through the English Channel, and bringing along with the former, high water to London, must pass on northwards, and in doing so, will enter the Frith of Forth considerably earlierthan the northern wave passings outhwards. Now, this southern wave, smaller, but earlier than the other, appears to enter the Frith, and may be traced at every station. It is followed up, however, very rapidly, by the great northern wave, and the former moving more slowly than the other, according to the law of the great wave of translation, is overtaken by it at the higher parts of the Frith, and being both greatly exaggerated by the form of that channel, produces the two tides of the Frith of Forth. Mr. Russell expressed his opinion, that the tides in the upper part of the Frith of Forth would be found to rise as high above the mean level of the sea, as the tides of the Bristol Channel. The observations on this subject were not, however, completed, but would be finished in the course of next year.

Mr. Fox's Electrical Experiments.-Mr. Spencer detailed the following experiment. He took a piece of sulphuret of copper, and placed it in a narrow glass vessel half filled with sulphate of copper in solution, and immersed the sulphuret about half its length in this solution. He then added common salt, taking care that it should not intermingle with the cupreous solution underneath. He then placed in the dark, and left it for a week. At the end of that time he examined it, and had the satisfaction of observing that several portions of it had become covered with very minute crystals of the pure metal.

At the end of a fortnight still more beautiful crystals had been deposited. This experiment, Mr. Spencer stated, was made for the purpose of corroborating the experiment of Mr. Fox, in which that gentleman took a small portion of sulphuret of copper, to which he attached a piece of copper-wire, and at the other end a portion of zinc; the arrangement was separated by a wall of clay, with sulphate of copper in solution in one cell, and a saline solution in the other. Mr. Spencer conceived, that by his arrangement the objection to Mr. Fox's experiment was overcome, viz. that it was always necessary to suppose the presence of two metals.

New Voltaic Battery.-A small voltaic battery of extraordinary energy, was described by W. R. Grove, Esq. :-In a letter published in the Phil. Mag. for February, I stated (said the author) some reasons for hoping that by changes in the constituents of voltaic combinations of four elements, we might greatly increase their energy. At that period I sought in vain for improvements, which a fair induction convinced me were attainable, but, being in the country, all my experiments were with copper, as a negative metal. I was constantly unable to use concentrated nitric acid as an electrolyte, and its importance never occurred to me until forced upon my notice by an experiment, which I made at Paris for a different object. This was an endeavour to prove the dissolution of gold in nitro-muriatic acid to be an eletrical phenomenon, or rather that this (as I believe, with Sir Humphry Davy, every other chemical phenomenon,) could be resolved into an electrical one, by operating on masses instead of molecules. The experiment was the following:-The extremities of two strips of gold leaf were immersed, the one in nitric, the other in muriatic acid, contact between the liquids being permitted, but mixture prevented by an interposed porous diaphragm. In this case the gold remained undissolved for an indefinite period, but the circuit being completed by metallic contact, either mediate or immediate, the strip of gold in the muriatic acid was instantly dissolved. Thus, it seems, that the affinity of gold for chlorine is not able alone to decompose muriatic acid; but when it is aided by that of oxygen for hydrogen, the decomposition is effected. The phenomenon bears much analogy to ordinary cases of double decomposition. The two gold strips in the experiment being connected with a galvanometer, occasioned a considerable deflexion; and it now occurred to me, coupling this experiment with my previous observations, that these same liquids, with the substitution of zinc and platinum for the gold

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leaf, would produce a combination of surpassing energy. My expectations were fully realized; and, on the 15th of April, M. Becquerel presented to the Institute a small battery of my construction, consisting of seven liqueur glasses, containing the bowls of common tobacco-pipes, the metals zinc and platinum, and the electrolytes concentrated nitric and dilute muriatic acids. This little apparatus produced effects of decomposition equal to the most powerful batteries of the old construction. I have since this tried various combinations upon the same principle, and though some of the rarer substances such, for instance, as chloric acid -have produced powerful effects, I have found none superior, and few equal to the preceding. I have, therefore, directed my attention to using these materials, and rendering the apparatus more economical, although I soon found that it was not so expensive as it at first appeared-the platinum remaining unaltered. Dilute nitric acid dimishes the energy; nitro-sulphuric acid acted as an electrolyte much as nitric acid; it is an excellent conductor, yielding oxygen at the anode, and hydrogen at the cathode. Applying this to my battery, I found it to succeed admirably, and hence a considerable diminution of expense on the side of the zinc, and found salt and water nearly equal to dilute muriatic acid. It also removes the necessity of amalgamating the zinc; but it sometimes, though rarely, disaggregates the porous ware, from the crystallization of nitrate of soda; and, therefore, in large batteries, I should prefer muriatic acid diluted with five times its volume of water. By using flattened parallelopiped shaped vessels, the concentrated acid is much economized and the metals approximated. Now, according to Prof. Ritchie, the power is inversely as the square root of the distance between the metals. The hastily constructed battery which I have to present, consists of an outer case of wood, height 7 inches, breadth 5, width 3, (it should be of glazed earthenware, similar to the Wollaston troughs,) separated into four compartments by glass divisions; in these compartments are placed four flat porous vessels, the interior dimensions of which are 7, 2, and 3-10ths of an inch, the thickness of the walls inch; they contain each three measured ounces; the metals, four pairs, expose each a surface of 16 square inches, and the battery gives, by decomposition of acidulated water, 3 cubic inches of mixed gases per minute; charcoal points burn brilliantly, and it heats 6 inches of platinum-wire of an inch diameter; its effect upon the magnet, when arranged as a single pair, is proportionally energetic; it is constant for about

an hour without any fresh supply of acids. The porous vessels are identical in their constitution with the common tobacco-pipe. As far as my experiments go, its power, with reference to the common constant battery, is cæteris paribus as 6 to 1, but the relative proportions vary somewhat with the series. The cost of the apparatus is 27. 28. During the operation of this battery, the nitric acid, by losing successive portions of oxygen, assumes first a yellow, then a green, then a blue colour, and lastly becomes perfectly aqueous; hydrogen is now evolved from the platina, the energy lowers, and the action becomes inconstant. It is worthy of remark, as an argument for the secondary nature of metallic precipitation by voltaic electricity, that the oxidated or dissolved zinc remains entirely (or at least by far the greater portion) on the zinc side of the diaphragm; the hydrogen alone appears to be transferred; and yet the reversal of affinities which the theory of reduction by nascent hydrogen supposes, is an enigma difficult of solution. I have invariably observed in this battery a current of endosmose from the zinc to the platinum, or with the current of positive electricity.

In

The rationale of the action of this combination, according to the chemical theory of galvanism, appears to be as follows:In the common zinc and copper combination, the resulting power is as the affinity of the anion of the electrolyte for zinc, minus its affinity for copper; in the common constant battery it is as the affinity of the anion for zinc, plus that of oxygen for hydrogen, minus that of hydrogen for copper. the combination in question, the resulting power is as the affinity of the anion for zinc, plus that of oxygen for hydrogen, minus that of oxygen for azote. Nitric acid being much more readily decomposed than sulphate of copper, resistance is lessened and the power increased; and no hydrogen being evolved from the negative metal, there is no precipitation upon it, and consequently no counteraction. I need scarcely add a word as to the importance of improvements of this description in the voltaic battery. This valuable instrument of chemical research is thus made portable, and by increased power in diminished space, its adaptation to mechanical, especially to locomotive purposes becomes more feasible.

(To be continued.)

NOTES AND NOTICES.

Submarine Galvanic Telegraphs.-We have received another communication from our friend Mr. Steele on this subject, in which, alluding to what he calls "the mooring power" of the steam engine, described in our last number, he observes, that "his flexible tube, containing the galvanised wire, and his steamers, however powerful, are not an electric eel, which can live as comfortably in the storm as in the calm, he only proposes his," he says, "as a moderate-weather theory." He also observes in this letter that, "supposing the tube to be graduated, between the knowledge of position to be obtained by the graduation and the compass in communication together, the steamers could under ordinary circumstances keep their relative places with considerable precision." Mr. Steele anticipates that some highly interesting experiments may be made in electro-magnetism and magnetoelectricity, (particularly since the introduction of iron-steamers) by the application of the theory which he has proposed for the consideration of our readers.

Electro-Magnetic Navigation. Mr. Faraday recently received a letter from M. H. Jacobi, dated St. Peterburgh, on the application of electro-magnetism to navigation, and Mr. Faraday has caused it to be inserted in the London and Edinburgh Philosophical Magazine for the current month. The following is a short extract from this very curious paper:-"In the application of electro-magnetism to the movement of machines, the most important obstacle always has been the embarrassment and difficult manipulation of the battery. This obstacle exist no longer. During the autumn of 1838, and at a season (in 1839) already too advanced, I made, as you will have learned by the Gazette, the first experiments in navigation on the Neva, with a ten-oared shallop, furnished with paddle-wheels, which were put in motion by an electro-magnetic machine. Although we voyaged during entire days, and usually with ten or twelve persons on board, I was not well satisfied with this first trial, for there were so many faults of construction and want of insulations in the machines and battery which could not be repaired on the spot, that I was terribly annoyed. All these repairs and important changes being accomplished, the experiments will shortly be recommenced. The experience of the past year, combined with the recent improvements of the battery, give as the result, that to produce the force of one horse, (steam-engine estimation,) it will require a battery of twenty square feet of platina, distributed in a convenient manner, but I hope that eight to ten square feet will produce the effect. If Heaven preserve my health, which is a little affected by continual labour, I hope by next Midsummer I shall have equipped an electro-magnetic vessel of from forty to fifty horse-power."

Card-making Machine.-At the model exhibition of the British Association, one of the inventions which attracted most attention was a machine for the fabrication of carding web. This delicate and ingenious instrument unwinds the wire from the reel, bends it, cuts it, pierces the holes, inserts the tooth, drives it home, and lastly, gives it, when inserted, the requisite angle, with the same, or rather with greater precision and accuracy, than the most skilled and readiest set of human fingers could; and with so great expedition that one machine performs a task which would require the labour of at least ten men. An engine of five-horse power, would drive, it is calculated, one hundred such machines.