of Latreille. It has at the base of the abdomen an elevated horn, going forwards as far as the head, where it terminates by a bend back. M. Latreille has ascertained that this horn is the sheath of the wimble, an instrument with which many other hymenoptera are furnished, but which is usually differently placed. The base only of the wimble of the diapria is contained in its horn; but the point issues, as usual, from the anus.

M. Latreille has given us a very detailed description of certain crabs of the Mediterranean, very remarkable from having their eyes placed, not, as in the ordinary crabs, upon a single moveable articulation, but upon a long tube with two articulations, so that the animal moves them like the branches of a telegraph. Their hind feet are placed upon the back, like those of the dorippes. Some of these crabs had been already observed by Rondeletius and Aldrovandus, but these ancient naturalists did not mention the singular structure of their eyes. M. Latreille forms them into a genus, under the name of hippo-carcinus. Almost at the same time Dr. Leach, a skilful English naturalist, who is occupied with a great work on crustaceous animals, described these species under the generic name homolus.

M. Savigny has established last year, by many observations, an analogy of structure much greater than was supposed between the mouths of winged instruments, whether suckers or masticators; and he has shown that the sheaths of the suckers, trumps, and other instruments of deglutition of the first, and sometimes these instruments themselves, may be considered as prolongations of some of the palpæ and jaws of the others. He has presented this year a great work, from which result analogies of another order, between the mouths of the ordinary masticators and those of certain genera which appeared anomalous, some of which have been arranged among crustaceous animals, and others among insects without wings.

Naturalists had remarked for a long time that a part of the jaws of these genera with extraordinary mouths resembled feet, and M. Savigny endeavours to prove that they are really feet, which, assuming more or less the form and the functions of jaws, join themselves to the jaws properly so called, or even take their places altogether.

Thus in the scolopendra there exist two sorts of supernumerary lips, of which the outermost have strong, hooked palpæ, which serve the animal for seizing his food. M. Savigny observing that they are not connected with the head, but with the first ring of the body, considers them as the first two pair of feet metamorphosed.

In the crabs, in which the head and corselet are confounded together, the supernumerary jaws are evidently the first feet; frequently their form even, as in the squillæ, is pretty evident. But in these animals, and in several others, whose mouth the author has described with infinite attention, there always exist ordinary jaws. On the other hand, in spiders, scorpions, and other genera withou

antennæ, there remains scarcely any trace of head, and the true jaws have disappeared. There exist only supernumerary jaws, that is, feet converted into jaws.

Such is a short sketch of a very original work, the proofs of which have for their basis observations so long and so numerous, that we cannot find room for them in our analysis.

M. Delabillardiere, who continues to observe his bee-hives, has made some new observations on that subject, so admirable and so inexhaustible.

It is known that, after the last swarm has left the hive, the working bees, similar in point of ingratitude to many other more elevated beings, make haste to rid themselves of the males, which are no longer necessary for propagation, and the support of which would consume a great deal of provisions. They make a dreadful carnage of them; but if we are to judge by the expressions of some authors, this business is always terminated in a few days. In fact, however, it lasts several weeks. When the hives are weak, or contain but few working bees, the operation lasts a much longer time. The males are even altogether spared in those hives that contain no queen, or when the queen, as sometimes happens, produces only males. M. Delabillardiere gives a detailed example of this rule, already recognized by Huber. Those who keep bees, therefore, may discover by the great number of these drones remaining in the hive after the usual time, that no more new swarms are to be expected from it, and that the hive may be rifled without inconve→ nience.

Every body knows the noise similar to that of the balance of a pendulum, which has long inspired the superstitious with terror, and which has received the name of death-watch. Naturalists soon supposed that it must proceed from an insect. Some have ascribed it to a spider; others to the little animal wood-louse; and others to the little coleopterous animal called vrillette, because it pierces wood with an instrument like a drill (vrille). Among those who have adopted the last opinion, some ascribe the noise to the perfect animal, others to its larva; and all have supposed that it produced the noise while boring the wood, either as food, or to make its way through it. M. de Latreille had observed that the vrillette makes the noise, not while boring wood, but by striking. M. Delabillardiere has established the same fact by a series of observations; and as he made them on a female, he supposes that the object of the noise is to call the male, as is the case with many other female insects at the time of propagation. *

*All this, and a great deal more, was long ago described by Allen and Derham in the Phil. Trans. vol. xx. p. 376; vol. xxii. p. 832. This animal is the ptinus pulsator of Linn. Derham describes and figures another animal that also beats. Phil. Trans, vol. xxiv. p. 1586.-T.

(To be continued.)

ARTICLE IX.

SCIENTIFIC INTELLIGENCE; AND NOTICES OF SUBJECTS
CONNECTED WITH SCIENCE.

I. Fulminating Platinum.

Mr. Edmond Davy, Professor of Chemistry to the Cork Institution, has recently discovered a fulminating compound of platinum, which has some curious properties. He is at present engaged in examining this substance, and will shortly make known the results of his investigation. This peculiar compound explodes at a moderate heat. This effect is accompanied by a flash of light. The substance is completely decomposed, and resolved into metallic platinum and gaseous products. When the fulminating platinum is put into liquid ammonia it is partially decomposed, and a quantity of gas is evolved. In ammoniacal gas, this substance becomes ignited. When it is moistened with alcohol a slight crackling noise is produced. The substance scintillates, and burns with a red flame.

II. Demonstration that no Part of a Circle is a straight Line. A Correspondent, who subscribes himself A Constant Reader, has sent me the following demonstration that no part of a circle is a straight line:—

C m

n

B

In the arc A B of a circle take a small part, A C, which suppose to be a straight line. But if AC is a straight line, C B, which is equal to it, must be a straight line. For the same reason nm, which includes A/ the point in which A C and CB are joined, is also a straight line; and therefore the whole arc AB is a straight line, which is evidently absurd. Therefore no part of a circle is a straight line.— Q. E. D.

9

Whether any part of a circle is, or is not, a straight line, is a point of difference between some of our most celebrated mathematicians. On the assumption that a circle is composed of a number of small straight lines, Hutton, Leslie, and several other great geometers, have built some very important theorems. On the contrary, an ingenious writer in the Quarterly Review for 1810, with several others, declaim strongly against the principle. Simpson and Legendre have likewise discountenanced it. The subject is, therefore, of considerable importance; and the above demonstration appears to me satisfactory.

U.

Seing in your Annals of Philosophy that Professor Playfair claims the invention of making barometers with an iron tube and a float,

I beg leave to inform you that I have one in my possession that has been made near 20 years since, which you may inspect at any time. I am, Sir, your most obedient humble servant,

182, Strand, April 13, 1816.

SIR,

IV. Fermenting Heat-Steam.

(To Dr. Thomson.)

H. CARY.

It is well established that a degree of moisture is essential to the fermentation of vegetable matter, and also an elevation of temperature above the freezing point. About 60° of Fahrenheit's scale is considered favourable for many common processes in the arts; but I am not aware that it has been determined at what higher degree fermentation would be checked, and what still farther augmentation of temperature would entirely arrest its progress. In summer time good housewives frequently preserve milk from "turning sour," and also their conserves, by scalding. It is of importance to ascertain this augmentation of temperature exactly, particularly with regard to the operations for deoxidizing indigo. You will allow me, therefore, to make the inquiry. At the same time permit me to ask if it has been determined what degree of pressure has been found most economical and advantageous in the employment of steam, to work that grand but expensive instrument, the steam-engine? Your obliged,

C, April 9.

DEAR SIR,

V. On the Pavement of London.

(To Dr. Thomson.)

A. M.

The bad state of the pavement in almost every street in London and Westminster where carriages of great burden are in the habit of going, cannot but be visible to every person who pays the slightest attention to the streets. It is a subject, I believe, which has lately engaged the particular attention of several public bodies, and may not be unworthy of a place in your Annals.

On passing the workmen now employed in paving that part of the Strand just beyond Somerset House, 1 observed that the stones' were all shaped like wedges, having the narrower extremity downwards, viz. :

I am not informed upon what principle this is done, but, according to my ideas, it does not appear to be the best method of securing the uniformity, or preserving the strength, of the pave

ment. If the stones were laid alternately with the narrow and broad ends downwards, I am of opinion that a greater regularity would be preserved; for by drawing a line, as represented, down the intersertion between, it will be seen that as one of the stones is forced downwards, the adjoining ones are liberated in a proportionate degree.

It certainly would be a more effectual way to let the stones, if hewn in a wedgelike form, alternate with one another thus

In this case a weight upon the centre stone would press equally upon the two adjoining ones; and a weight upon the stones having their broad ends downward would not be so liable to force them in as what it would upon a stone narrowed downwards.

I conceive, however, that as the stones are shaped for the purpose of paving, a different arrangement might be made of them, more conducive to strength and durability; for instance, an alternation of stones in the following shape,

ΩΣ

laid together, would rest upon one another through the whole line, and, like an arch, would receive much strength and security by resting upon a strong curb or butment.

Should these observations be thought worthy of a place in your Annals for the next month, it will much oblige, Dear Sir, yours very truly,

6, Adam-street, April 25, 1816.

J. H. H. HOLMES.

VI. On the Ore of Copper described and analysed in the Annals of Philosophy, vol. vii. p. 321.

From your late publication, I perceive you give us your own recent analysis of what you consider as a new ore of copper, in which you have considered the whole of the copper in a state of peroxide as combined with carbonic acid, and that the silex is a stranger to the constitution of the mineral.

I shall just remind you of the passage in the late tract of Berzelius, published by yourself, p. 35, and of the analysis of Lowitz published by Lucas, part 2d, p. 353, that afford reasonable ground for not rejecting the silex as a constituent in the mineral dioptase, which your new ore much resembles in its external characters.