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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 under. goes 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 laminæ 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 laminæ 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 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 Níethod 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 soo 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 ema broidery, sometimes begin with a rod that is about three inches in diameter, and ultimately obtain wires that are as small as zão 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 oso; 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 doof an inch, and then filled the mould with silver. When this rod was drawn to is, my platina was reduced to ro's, and by successive reduction I obtained wires of 106 and dog each excellent for ap.
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 having only one tusk.
Mathematics and MECHANICS. 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. RS.-Haying 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
« * No very accurate observations can be made with a telescope shorter than thirty inches, and at that distance too of an inch subtends only one second of a degree,'
in a brass plate, of a small perforation being made by the side of it, of about its of an inch : so that the eye may view the object proposed for examination, and at the same time see distant objects through the adjacent perforation, by which the apparent magnitude of the image may be compared with a scale of inches, feet, or yards, according to the distance at which it might be convenient to place it. Dr. Wollaston, however, makes use of a scale of smaller dimensions attached to the instrument: with which he conceives that he can estimate the real magnitude much more accurately than by any other means. If, for instance, the object measured be really ozoo, it may appear by the instrument to be toooo or otori in which case, the doubt amounts to sth part of the whule: whereas, in the usual construction, an instrument professing to measure to the same extent, or, to totoo of an inch, cannot distinguish between roboo and toooo i because, though the eye may be able to perceive that the truth lies between the two, it receives no assistance within part of the larger measure.'
Some papers by the Astronomer Royal, in each portion of this volume, will be considered with the other contents of Part II. in our next Number.
[To be continued.]
ART. IX. The rear, a Poem. By John Bidlake, D.D., of Christ.
church, Oxford, Chaplain to their Royal Highnesses the Prince Regent and the Duke of Clarence. 8vo. Pp. 236. Jos. 6d.
Boards. Rees. 1813. How happy is it when persons who are afflicted with blind11 ness can amuse themselves; and happier still should they find that they can also amuse others ! Men of genius and improvement enjoy this enviable privilege, that, when “knowlege at one entrance is quite shut out,” they can, nevertheless, “sit in darkness, and enjoy bright day ;” and to them the horizon of intellect appears luminous and resplendent. Dr. Bidlake may be said to have belonged to this distinguished class. Though deprived of bodily sight, to the orb of his mind the beauties of the creation still presented themselves with their accustomed charms; and his poetic landscapes shew that he had minutely noticed and powerfully felt each varying aspect of the changeful seasons.
Scarcely, however, had he proved to the world, by the pub, lication of this poem, that he could thus pleasingly and lauda ably contend against the privation to which he had been doomed, when we learned that a sentence had been passed on him against
which he had no appeal nor resource, and that his mental as well as corporeal eye was for ever closed in this life! -He has long been known to the literary world; and the termination of his career has been remarkable, both for the rapid succession of a severe affliction and of the last sad scene, and for the choice which he happened to make for the concluding effort of his mind:— that, unknowingly on the verge of eternity, he should chance to select for the subject of his poetical contemplation the natural features of our « little year.”
By such a choice, the Doctor has unavoidably reminded us of Thomson: but his descriptions are less majestic and glowing; and his verse is more in the easy manner of Cowper, in « The Task ;” while his reflections occasionally wear the tints of that mournful monitor Young. To Milton, also, he is now and then indebted for a phrase. — We are informed, in a short advertisement, that the scenery in the beautiful neighbourhood of Plymouth suggested the principal part of the rural landscape which occurs in the course of the work, and that the observations are principally confined to the climate and local peculiarities of Devonshire: To each month, a distinct book is assigned; and, as the poet proceeds from January to December, every vicissitude of the year, as indicated by the state of the atmosphere, the appearance of the earth, the productions of the vegetable world, the labours and diversions of man, and the instincts of animals, is minutely recorded. As appropriate to the present moment, we shall first copy a part of his sketch of the most beautiful and most welcome of all months :
. . . . May.
Now breathes ethereal softness, while the sun
" Hail ! lovely month on whose fair train await
· And thou too, hail! Spirit of vital heat,