this condensation gives opportunity for a fresh quantity to arise from the opposite ball, with proportional reduction of its temperature.

According to a theory that does not admit of positive cold, we should represent the heat of the warmer ball to be the agent in this experiment, generating steam as long as there remains any excess of heat to be conveyed. But if we would express the cause of its abstraction, we must say that the cold mixture is the agent, and may observe, in this instance, that its power of freezing is transferred to a distance, by what may be called the negative operation of steam.

The instrument, by which this is effected, may aptly be called a Cryophorus, which correctly expresses its office of frost-bearer.' A Description of the Solvent Glands and Gizzards of the Ardea Argala, the Casuarius Emu, and the long-legged Casowary from New South Wales. By Sir Ev. Home, Bart., F.R.S. F.R.S.-Pursuing his inquiries into the comparative structure of the digestive organs of the different species of carnivorous birds, Sir Everard Home here describes those of the Ardea Argala, a native of Bengal, of the Casowary of Java, and of the long-legged Casowary of New South Wales. The solvent glands of the Ardea consist of 5 or 6 cells, which open into one common duct, disposed in two circular masses, one on the anterior and the other on the posterior surface of the cardiac cavity; something in the manner of those of the Cormorant. The gizzard is like that of the Crow. The Casuarius Emu, which inhabits Java, has solvent glands in the form of oval bags, occupying the whole surface of the cardiac cavity. Its gizzard, as to strength, resembles that of the Crow; but it is peculiarly situated, being out of the course of the cardiac cavity, so that the food, in passing along the intestines, does not necessarily go through it. In the Casowary from New South Wales, the glands are very similar to those of the former bird; the gizzard is stronger, but resembles it in other respects.

The paper concludes with some interesting observations on the comparative anatomy of the digestive organs of birds which are generally similar as to size, food, and habits, but which are placed in countries that differ with respect to the facility of acquiring food. The Casowary of Java, living in a most luxuriant region, has its solvent glands small, the gizzard so situated as to be used only occasionally, and the intestines short. The Casowary of New South Wales, inhabiting a less fertile country, has its glands rather larger, and its gizzard stronger, and placed in the same situation: but the intestines are double the length. The Rhea Americana, living in a part of South America in which food is not plentiful, has large glands and a strong gizzard, through which all the food must pass; and the intestines

are

are of still greater length, The Struthio Camelus of the desarts of Africa has more numerous glands, a stronger gizzard, and a much longer intestinal canal.

Additional Remarks on the State in which Alcohol exists in fermented Liquors. By W. T. Brande, Esq., F.R.S.- In a former communication, the author had endeavoured to prove that the alcohol, which is obtained by distillation from fermented liquors, is an educt, and not a product of the operation. He has since found means still farther to substantiate his opinion, by procuring alcohol from wine without the intervention of heat; and in a quantity equal to that which would have been produced by distillation. The subacetate of lead possesses the property of precipitating from wine all its acid, and its coloring matter; leaving in the fluid only water, alcohol, and a portion of the acid of the metallic salt. The alcohol may then be separated by potash, and its quantity easily ascertained. This process was tried on port wine, and compared with the result of distillation; when the amount of alcohol was found in both cases to

be very nearly the same. Similar experiments were repeated on madeira, sherry, claret, and vin de grave, with equally decisive results: so that the author conceives it to be amply proved, by experimental evidence, that no alcohol is formed during the distillation of wines, and that the whole quantity found, after distillation, pre-existed in the fermented liquor.'.

On a new Variety in the Breeds of Sheep. By Col. D. Hum phreys, F.R.S. This paper gives an account of a new and permanent variety in the sheep, which was produced, without any assignable cause, on a farm a few miles from Boston in North America. It acquired the popular name of the Otterbreed, from the shortness of its legs and the length of its back; and it received the more appropriate title of Ancon-sheep, from the projection of its joints, which assume the appearance of elbows. The shortness of the legs, and a degree of weakness or imperfection in the articulations, seem to be the most characteristic marks of this variety: the sheep are hence rendered less active, and less able to leap over fences, a circumstance which appeared likely to prove of some advantage in a country without good hedges, and where the keeping of sheep is not an object of much attention. This recommendation, however, it may be presumed, has not been found to answer the expectations of the breeders, since we learn that this variety of sheep is now become very rare.

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Experiments to ascertain the Coagulating Power of the Secretion of the Gastric Glands. By Sir Ev. Home, Bart., F.R.S. The following are the most important experiments related in this paper. A comparison was made between the coagulating

power

power of the cardiac portion of a chicken's stomach, and the horny lining of the gizzard, by adding milk to an infusion of these parts; coagulation took place in both of them, but the infusion of the gizzard produced the firmest curd. The cardiac portion of the stomachs of a hawk and of a fowl were then compared; when that of the hawk was found to be the most powerful. Infusions of the gastric glands of the turkey, of common rennet, of the lining of the cardiac portion of the turkey's stomach, and of the recent calf's stomach, were also compared. The rennet acted the most readily; the gastric glands and the recent calf's stomach were less powerful, and in about the same degree; while the cardiac cavity produced the least effect. The author draws the following conclusions from his experiments:

It is clear that the secretion of the gastric glands possesses the power of coagulating milk, and gives that power to all the parts by which it is imbibed, whether composed of living parts or not, since the horny lining of the gizzard, the mucus in the stomach, and the inner membrane of that cavity, appear equally to have acquired it.

This coagulation appears to be the first change the food undergoes in the process of digestion, and where the digestion is rapid, the coagulated parts are very quickly dissolved.'

On some Properties of Light. By David Brewster, LL.D., F.R.S. Ed. In the course of some experiments which Dr. Brewster has been lately performing on the transmission of light through diaphanous bodies, he was led to inquire whether a property could be given to transmitted, similar to that which was observed by Malus with respect to reflected light. In this object he was unsuccessful: but, while he was employing a thin plate of agate, on each side of the luminous object seen through it, he observed that a highly coloured image was produced, forming with the object an angle of several degrees. This coloured image was found to possess the same property with the image through a double reflecting crystal; and by viewing it through a prism of Iceland spar, and turning the prism on its axis, the images alternately vanished at every quadrant of their circular motion. Besides this coloured image, a faint nebulous light also accompanies it, lying in a direction parallel to the lamina of the agate. The power is said to be also possessed by the cornelian and chalcedony.

Dr. Brewster offers some ingenious conjectures on the doubly refractive power of certain substances; which he conceives may depend on an alternation of lamina of two separate refractive and dispersive powers.' It has been supposed, since the time of Newton, that the refractive power of the diamond was greater than that of any other body: but Dr. B. has found the chromate of lead and realgar to be superior in this respect.

An

An Appendix to Mr. Ware's Paper on Vision. By Sir C. Blagden, F.R.S.-Sir C. Blagden's principal object is to confirm the facts that are stated in Mr. Ware's paper, of which an account is given in p. 70. He agrees with Mr. W. in the opinion that near-sightedness is often caused at an early age; that it is more frequent in the higher ranks; and that a large proportion of the students at the universities make use of concave glasses. These effects, he conceives, are owing to the habit of looking at near objects.

'Children born with eyes which are capable of adjusting themselves to the most distant objects, gradually lose that power soon after they begin to read and write; those who are most addicted to study become near sighted more rapidly; and if no means are used to counteract the habit, their eyes at length lose irrecoverably the faculty of being brought to the adjustment for parallel rays.'

All these points he confirms by a reference to the change which has taken place in his own eyes.

A Method of drawing extremely fine Wires. By W. H. Wollaston, M.D., Sec. R.S.Musschenbroek mentions an artist of Augsburg, who was able to draw a gold-wire so fine, that 500 feet of it weighed only one grain. This account has been doubted, but Dr. Wollaston points out a method by which a still finer wire may be formed. We quote the paragraph in which he describes the process:

Those who draw silver wire in large quantities for lace and embroidery, sometimes begin with a rod that is about three inches in diameter, and ultimately obtain wires that are as small as of an inch in thickness. If in any stage of this process a rod of silver wire be taken, and a hole be drilled through it longitudinally, having its diameter one-tenth part of that of the rod, and if a wire of pure gold be inserted, so as to fill the hole, it is evident that by continuing to draw the rod, the gold within it will be reduced in diameter exactly in the same proportion as the silver; so that if both be thus drawn out together till the diameter of the silver is of an inch, then that of the gold will be only ; and of such wire five hundred and fifty feet would be requisite to weigh one grain.'

The wire thus drawn is then to be immersed in nitrous acid, which will dissolve the silver coating without injuring the gold.

To obtain a very fine platina-wire, a different method was employed:

‹ Having formed a cylindrical mould of an inch in diameter, I fixed in the centre of it a platina wire previously drawn to the of an inch, and then filled the mould with silver. When this rod was drawn to my platina was reduced to, and by successive reduction I obtained wires of and doo, cach excellent for ap.

plying

plying to the eye-pieces of astronomical instruments, and perhaps as fine as can be useful for such purposes.

The tenuity of these minute platina-wires was found to be greater than we might have expected; and the author suggests the possibility of their being applicable to some useful purposes, with directions for their management.

On the Tusks of the Narwhale. By Sir Ev. Home, Bart., F.R.S. Some circumstances having led to the belief that the female narwhale was entirely without tusks, and that the male had only one, Sir Everard was induced to examine a number of skulls, and to seek for information from different quarters; from which he concludes that the male has two tusks, but that the left tusk appears commonly long before the right one;' and that the female has likewise two tusks, but that they are late in making their appearance. It is very rarely that a female has been taken of sufficient age to possess two perfect tusks. The author remarks that this discovery will render it necessary to alter the specific name given by Linné, to this animal, which was derived from the idea of its havingonly one tusk.

MATHEMATICS and MECHANICS.

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On a remarkable Application of Cotes's Theorem. By J. F. W. Herschel, Esq. This memoir contains several remarkable properties of the conic sections; or rather, as the author observes, properties of their equations, in particular cases, for disjointed points, determined according to a certain law, and not of consecutive points constituting an entire line. When geometrically enunciated, therefore, they become complicated and unintelligible: but, when considered analytically, they assume a more simple form, and are not uninteresting. The theorems will not, however, admit of illustration without entering on the subject at greater length than is consistent with our plan.

Description of a Single-lens Micrometer. By William Hyde Wollaston, M.D., Sec. R.S.- Having had occasion to measure some very small wires, with a greater degree of accuracy than he was enabled to obtain with any instrument in present use, Dr. Wollaston was induced to consider other means of accomplishing his object, and was thus led to the construction of the simple instrument described in the present memoir. It consists of a single lens, of about of an inch focal length; which, being necessarily very small, admits, when mounted

T

* No very accurate observations can be made with a telescope shorter than thirty inches, and at that distance tends only one second of a degree.'

of an inch sub

in