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it is supported by a bed of vapour, whence it is concluded that its ebullition is impossible. M. Baudrimont arrives according to his experiments at the same conclusion. But I am convinced that this is incorrect. I made the bottom of the crucible a little convex within, then red-hot, I put in water drop by drop; this entered into ebullitionthe bubbles came principally from the centre, still it took two minutes and a half to evaporate.

"I placed within the crucible a very thin piece of platinum foil of the shape of a watch-glass; upon this I poured a volume of water; the foil was wetted and the water entered into ebullition, and, in spite of that, it took about two minutes and a half to evaporate."

The last three experiments, I confess, somewhat perplex me; the one marked 3. is unintelligible, and does not seem to warrant the deduction contained in the sentence; 4. contradicts my results when similar means were taken, for I had no ebullition, and the water within the crucible divided into spheres, each of which partook of the motion already described. This and the next experiment contradict M. Laurent's opening experiments with which I agree, and I also agree with the deduction, that when the water does not wet the hot crucible, evaporation is slow and imperceptible; and conversely, that when the water does wet the hot crucible, evaporation then is sudden and quick. I may add, too, that when water falls drop by drop into the hot crucible, evaporation is slower in proportion as the heat of the crucible is high, and vice versa. This is how I explain the discre pancy as to time-in my experiments the water often remained seven or eight minutes, whereas M. Laurent gives 21 minutes as the longest time, indeed as the only time, when the water was added drop by drop; but how he contrived this degree of exactness I cannot tell, for I have found as I have said, that the evaporation is quick or slow, according as the temperature is of less or greater intensity, and the same temperature cannot always be preserved. M. Laurent proceeds:

"I now wish to demonstrate that the water does not continually touch the crucible, but that it dances like a billiard-ball, or a marble (bille), let fall upon a horizontal 'plane.

"I would also prove, that if the water does not moisten the red-hot crucible, it is not,

as has been supposed, because it is supported by the vapour, for if it were so, the water would be violently and irregularly agitated, and it is precisely the contrary which happens? and besides, when the evaporation is slow the water does not wet the crucible, which it does when the evaporation is rapid."

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I may here observe, that the water is

irregularly agitated;" but, admitting this, it does not follow that it is "violently agitated:" yet, certain it is, that the water often, in consequence of this "irregular agitation," spits drops out of the crucible to a considerable distance. I am not quite sure that the term "violent" does not apply.

"In examining attentively the water just thrown into a red-hot crucible placed quite vertically in the furnace, it is seen to take alternately many figures of the greatest regularity.

"Sometimes it presents itself under the form of a wheel with four teeth, or 6, 8, 10, 12, always in equal number.

"These singular figures can be well ex plained in admitting,

"1. That the water does not wet the crucible for the same reason that mercury does not wet glass.

"2. That the globule of water is submitted to a vibratory movement which varies at every instant, and that this movement is produced by the vapour which is formed below whenever the drop of water touches the crucible; the drop elevated by the vapour falls in order to be again elevated, and so on."

M. Laurent then explains the change of form in the globule by a theory which bears a great resemblance to one formed by me several months ago, "On the modes of vibration of glass goblets and the changes they undergo during vibration." As my theory was written in September last, and sent to the Philosophical Magazine the first week in November, and M. Laurent's paper was published at the end of November last, and received in England only within the past month, it will be seen that we were both unconsciously pursuing a similar train of thought upon my favourite subject, vibration. I trust this digression will be excused, as I am anxious to

M. Laurent all due merit, and, at the same time, to prevent any inference discreditable to myself arising from the priority of publication, of which M. Laurent has the advantage. But, to resume his memoir,

"Let us suppose that an elastic circle is

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compressed at two points exactly opposite, it will take the figure of an ellipse; but if the compressing cause suddenly ceases, the ellipse, by its elasticity, will become at first circular, then the flattened part will pass over the circle by virtue of its acquired swiftness, and will give a new ellipse whose major axis will be perpendicular to that of the first. The circle before returning to its first state of repose will give a series of ellipses alternately perpendicular, and if these motions are rapid enough, the two consecutive ellipses will appear to exist simultaneously, and we shall see a wheel with four teeth.

"Let us suppose the circle to be compressed in three points equally distant, it will take the form of fig. 2.* By its elasticity, it will regain its first circular state, then it will pass over and take a figure inverse to the preceding, and so on; these movements becoming very rapid, we shall see a figure with six teeth. It will be the same for the figures with 8, 10, 12 teeth.

"In order to prove that these figures are due to the repeated falling of the water upon the bottom of the crucible, I have imitated them with mercury in the following man

ner:-.

"In a small hemispherical porcelain capsule I poured from 20 to 100 grammes of mercury, and placed the capsule upon an elastic ruler, which I vibrated strongly by means of a bow: the mercury immediately took the same figures as the water in the redhot crucible; but with mercury the difficult figures succeed each other very rapidly."

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I have already written more enough to be tiresome, and will not occupy your valuable space with further extracts or comments-I therefore conclude with one remark. I complain of M. Laurent chiefly for being too imaginative for seeing what he wished to see, rather than what he did see, and for straining after an analogy where scarcely any exists. He says that the globule of water in the red-hot crucible presents figures of the greatest regularity." With the exception of the spherical drops already alluded to, I have not found this to be the case. I have often watched the contents of the crucible, and have no hesitation in saying that its form and behaviour is uncertain and fitful in a great degree, and bears no relation to

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In the Number of the Annales" that I am translating from, there are no figures given; but in this case, it will be readily seen, that figure 2, referred to, must be somewhat that of a heart.

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PRODUCTION OF ANIMALS BY GALVANISMMR. CROSSE'S EXPLANATION.

(To the Editor of the Taunton Courier.) Dear Sir,-Having seen in a very recent publication what is stated to be an account of some experiment of mine, in which insects were produced instead of crystals, I take the earliest opportunity of making known, that such an account was published without my knowledge, and, that although the main fact is as there represented, yet that the mode of conducting such experiments is inaccurate. I am the more anxious to correct this statement, as several perfectly erroneous accounts have already appeared in different papers, calculated to produce a false impression in the minds of all but scientific men, who can, if they please, readily distinguish an error when they meet with one.

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I am sorry to observe that a gentleman of high repute (Dr. Ritchie), who seems to have forgotten both science and temper on the present occasion, has taken advantage of some such misstatements to form the weak foundation for a most illiberal attack upon me in the Literary Gazette, which I shall take an early opportunity of replying to as it deserves.

I must further request my friends and the public not to give credit to any publication as coming from me unless my name is attached; and as I detest nothing so much as a literary or scientific dispute, I had hoped to have glided through the remainder of my life without provoking the malevolence of the ill-disposed, and more particularly as I am unconscious of having done any thing to offend the most captious by presumption or misrepresentation.

I beg to remain, dear Sir, yours truly,
A. CROSSE.

Broomfield, Jan. 3.

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The history of the railway from St. Petersburgh to Zarskoeselo and Pawlowsk, which is by this time in operation, presents several remarkable points of contrast with similar works in England, which throw considerable light on the relative situations of the two countries. In England, all the railways executed and projected have a view to the promotion of trade, or the public convenience. In Russia, this, their first railway, is composed of two branches, running from the capital, one to the imperial residence of Zarskoeselo, and the other

to the middle of the park of the Grand Duke Michael. In England, the speculators would have had to go through an infinity of trouble and expense to procure an "Act"-in Russia all this roundabout process was avoided; as soon as the Emperor took the concern under his patronage, all difficulties vanished; an imperial ukase directed the immediate cession of all private lands on the line to the Company (compensation to be an after consideration), and conferred the privilege of carrying the railroad for a whole mile through the most crowded

streets of the metropolis, without troubling the "corporation of St. Petersburgh" for their consent. By the same means the Company were freed, for the first ten years, from what is here a pretty considerable nuisance-the payment of rates and taxes. The will of the Autocrat, however, was not sufficiently powerful to produce an effect which would have happened naturally enough in England-the manufacture of the railway and its appliances by "native talent." As a matter of course, the whole were imported from England; the rails from the Butterley and Bedlington Iron-works and the Welsh furnaces of Messrs. Guest, Lewis, and Co., and the pedestals from Butterley only. The locomotive-carriages were furnished by Mr. Stephenson, of Newcastle, Mr. Hack worth, of New Shildon, and Mr. Tayleur, of Warrington; their only foreign competitor, too, was foreign in residence alone-Mr. Cockerill, the English iron-master of Liege, in Belgium. Some of the English locomotives were tried on railways here before being shipped for their destination, and, if report can be relied on, went at the rate of 75 miles an hour! The only party not English about the concern appears to have been the chief engineer, Von Gerstner, a German-and he received his railway-education in this country, which he visited on purpose. Every article of mechanism required came ready-made from England :-the weighing-machines were supplied by Mr. Kitchen, of Warrington; a crane, by Sharp and Roberts, of Manchester; clocks, with illuminated dials (in the style of our first-rate gin-shops), by Mr. Paine, of London; and even the "trumpet-machines," which the Company are compelled to use, to give notice of the approach of their carriages when traversing the streets of St. Petersburgh, were manufactured in our own metropolis, by Messrs. Robson and Son. Each carriage is also provided with an apparatus (which will not be without its use in such a climate as that of Russia) for removing frozen sleet and snow from the rails.

The railway is 18 miles in length, that is, the Pawlowsk branch, which was the first undertaken, It terminates in the centre of the Grand Duke's park, where the Company have erected a large building as a house of entertainment, their principal dependance for remuneration

being on the holiday-makers of St. Peters burgh, who, they calculate, somewhat in the fashion of similar speculators nearer home, will pass along it at the rate of 1,500,000l. per annum, though their expectations of a profit of 13 per cent. on their capital of 3,000,000 rubles (135,0007.) are based on the supposition that no more than 300,000 will make use of their conveyances. At present it is reckoned that the number of horses employed in keeping up the communication is 178,187 in the year. The time required to perform the distance on the railway will be half an hour only, and the (lowest) fare half a ruble; while the diligence takes from two to three hours, and charges three rubles. The works were commenced in April, and the first line was expected to be finished in six or seven months, as, with the powerful patronage of the Czar, physical obstacles were the only ones that had to be encountered.

PERPETUAL MOTION.

Sir, I was much surprised, on looking through your 696th Number, to see that any one else should have been induced to make an attempt at perpetual motion on Mr. Mackintosh's plan, as shown at p. 149, when it must be plain to every one, that gravity, the very power which was intended to give motion to the wheel, is completely neutralised by the power of the magnet; and that the backward motion described by Mr. Mackintosh, and verified by Mr. Monro (see p. 192), proves nothing more than that the friction between the ball and the wheel was greater than the friction on the axle of the wheel. The suggestion of the ratchet, to prevent the said retrograde movement, was certainly good, as proved on its application by Mr. Monro; but I am at a loss to understand how any one having the slightest smattering of mechanical knowledge, could imagine it should have any tendency to reverse the only motion produced. But I should say, the most extraordinary part of the affair is, that a rational being could be led, by the failure of so futile an attempt, to conclude that gravity, in the hands of the great Creator, is insufficient to produce that, which he (Mr. Mackintosh) in his experiment had taken most effectual means to prevent.

Yours, &c.

TREBOR VALENTINE.

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