We have received the second part of the Illustrations of Scotland, which rivals the first in beauty and interest; but as our limits will not allow us to do justice to the merits of this work in the present number, we are reluctantly compelled to defer a notice until our next publication.

The Doctrine of Proportion, or geometrical admeasurement by similar triangles, practically applied to extending or diminishing drawings.

London: Ackermann.

To the expert geometrician who is unacquainted with the art of drawing, or has no "natural taste" for it, this work will prove extremely serviceable, and enable him to use his scientific acquirements very amusingly; but we think it is to geometricians alone that it will render essential service. The author imagines his doctrine of similar triangles will supersede the present very simple and sufficient method, used by engravers, of reducing drawings by similar squares. We cannot agree with him in this expectation, inasmuch as it implies the study of an abstruse science as absolutely necessary, before the principles of this new doctrine can be understood; whereas, the old system of squares is simple enough for a child's comprehension, and has certainly been found to answer every required purpose with positive accuracy. The doctrine exemplified in the handsome volume before us, is an admirable one for persons conversant with geometry, and is illustrated by well-executed plates demonstrating the system; but we must candidly confess we have some doubts of the application of this principle being universally adopted.

Roscoe's Wanderings through North Wales Parts X., XI., and XII. London: Tilt. Birmingham: Wrightson and Webb.

Mr. Roscoe's wanderings proceed very pleasantly to his readers, and from the high interest and picturesque beauty of the scenes he describes, the veritable tour must have been equally agreeable to himself. His account of the beer-shop increase, and hints for a temperance-society mission among the Welsh miners, should be seriously considered by some of the philanthropic tea-totalers of the fraternity. But our Cambrian neighbours are notoriously addicted to their libations of crw, and the habit is of such ancient standing that we fear it will be long ere the merry Welshmen consent to forswear their visits to the cottages whose "gaily bedaubed lures to intemperance" gave such uneasiness to our kind-hearted wanderer. He tells us that the public houses are "thick as autumnal leaves ;" and that, “in some places, every other house boasts its sign, from 'Uther's Dragon' and 'Prince Llewellyn,' to 'Glendower's Head and the Meredith Arms.'' He strenuously counsels an investigation, and consequent diminution, of these "painted sepulchres;" in fact, a Welsh beer-shop reform bill seems the grand desideratum

towards the civilization of our Cambrian neighbours, in Mr. Roscoe's opinion at least. His account of the South Stack Lighthouse and the Rothsay Castle steam-ship wreck, though not very novel, is very circumstantial; and the former subject is well illustrated by Mr. Creswick's view, where the flocks of Gulls, Guillemots, &c., flying about, make the air exhibit the phenomenon of a black and white snow-storm. The magnificent and gloomy scenery of Llynn Idwal is admirably depicted. The Menai Bridge does not appear to us a happy portrait of our old friend-it does not convey an idea of the vast height and dimensions of that wonderful structure. Barmouth, too, is far from a "flattering likeness." "The falls of the Ogwen into Nant Frangon," with the deep, rocky glen, and mountains soaring high above the clouds, make a splendid view. The Fall of the Machno is another spirited and sparkling picture. In the tenth number (which, by an oversight, we are noticing last instead of first) is a fine picture of Cattermole's, representing Prince Llewellyn and his Barons banqueting in his palace, near Aber. The rather gloomy expression of all the other countenances, and the deep, anxious thought which may be traced on that of the Prince, seem to tell a story of ill news having reached the palace-perhaps, of an English incursion-the thought of which not even the skilful harper can dissipate. There is much fine grouping and spirited drawing in this fine plate. The Vale of Ffestiniog, by Cox, is a scene of quiet, rural, picturesque beauty; where the winding river, the rich woods, with pleasant residences peeping from their verdant slopes, and towering peaks of craggy mountains rising in the background, form a scene uniting, in a singular degree, the beautiful and sublime of British landscape scenery. In this view, as in that of the Rhaidyr y Wenol, Mr. Cox has been extremely happy in the point of view; though the falling sheet of water in the latter plate seems to us as displaying a flatness and fixedness not desirable in such subjects: but the work, " take it for all in all," is one of such beauty, that to cavil at small and only occasional imperfections were ungenerous and hypercritical.

Maund's Botanic Garden. Nos. 133, 134, and 135. London: Simpkin and Marshall.

THE plates of flowers in this elegant work are so correctly drawn, delicately engraved, and carefully coloured, as to prove admirable portraits of the beautiful originals. Being so arranged as for each volume to be complete in itself, this work is well adapted for presents, now that the study and culture of flowers has become so favourite an occupation with the young and fair portion of society.

171

SCIENTIFIC MISCELLANEA.

ON THE DETECTION OF DROWNED BODIES, BY THE REPRESENTATION OF THEIR FORMS ON THE ICE IMMEDIATELY ABOVE THEM.-It may not be generally known that, under certain circumstances favourable to the phenomenon, the outline tracery of figures reposing at the bottom of a sheet of water, are occasionally visible on the surface of the ice. I remember perfectly well, when many years ago hearing this asserted as a fact, it was considered as a pure phantom of the imagination by some, and by others as a miraculous interference of providence for the discovery of the body. It is, nevertheless, perfectly true; imagination has nothing to do with it; and the miracle resolves itself into a very simple, but curious, operation of natural causes, which, not for the first time, I have verified by repeated observations during the present winter; when my attention was recalled to the case by remarking, after a hard and sudden frost, the exact outline of a semicircular piece of masonry beautifully drawn in white lines in the ice, reminding me of the profile figures incased in solid glass by a patent process of (I believe) Messrs. Peilat and Green. To those who are in the habit of looking at things without much minute inquiry, the pictures drawn by an invisible power certainly assume a very mysterious appearance, and it can scarcely be matter of surprise that, if the figure of a human being above should prove, as it always must do, indicatorial of a human being below, an ignorant or superstitious person would naturally attribute such a manifestation as the result of a supernatural draughtsman. The explanation, however, is easy—merely this: we know that any body containing air, if heavier than water, must be emitting that air in minute portions or bubbles, struggling, by their lightness, to escape through the pores of the submerged body, and rising, if the water is perfectly motionless, in direct straight lines, to the surface. Suppose then, that, during the escape of such minute bubbles, a severe and sudden frost takes place; as a matter of course, on the very first formation of a thin film of ice, the ascending bubbles will be checked and detained by the crystallizing ceiling above them, and remain stationary, and in a few seconds be imprisoned; such will also be the fate of the successive series: and, consequently, if from every part of a subcumbent body, these minute particles are rising, a representation immediately above the body will be the obvious, effect. To those who may not have witnessed this interesting, surprising, but yet simple, phenomenon, the following easy mode of proving it by experiment is recommended. Take a piece of porous dry wood, and place it gently in a large shallow tub full of water, pressed down with some weights to keep it steady and prevent its rising, at a time when congelation is rapidly going on, and the air perfectly calm. In the morning, on looking at his tub, the spectator will, if everything has gone on favourably, be gratified with seeing the image of his piece of wood faintly or strongly depicted, and incorporated in minute bubbles through the surface of superincumbent ice, proportioned to the quantity or rapid rising of the stream of escaping air. It is scarcely necessary to add that should a human body chance to be in that peculiar state of decomposition, or putrefaction, when gases are generating and evolving, a rapid and abundant ascent of such gases will, on meeting the surface above, be imprisoned in thrilling characters of ribbed ice, to tell the fatal tale of what has taken place below.

E. S.

ASSAYING. The quantity of alloy which silver contains, is determined by cupellation. The process consists in fusing the alloy with a certain proportion of lead, upon a bed of bone ashes, termed a cupel. The oxidizable metals enter into combination with the oxide of lead, and sink into the cupel; while the silver, which resists oxidation, remains in a brilliant globule on the surface. The process is so elegant, so simple, and so rapidly performed, that it has been generally adopted, not only by individuals, but by the different European governments. It is a process, unfortumately, which is not deserving of confidence within less than 5 or 6 parts in a thousand. Alloys were made, by M. d'Arcet, containing exactly 950, 900, and 800 thousandths of silver, and samples of each sent to the principal assayers of Europe. Few of the trials approached within less than 4 thousandths, and some not within 7 or 8, of the truth. In some future number of The Analyst we intend to enter in detail upon this subject, which seems not to have excited that degree of attention in this country which a matter of so much importance demands. B.

SECRETIONS OF VEGETABLES. The following singular instance of secretion in the economy of vegetation, observed in the Coryanthus maculata, a native of Brazils, and belonging to that extraordinary class of flowers called epiphytes, has recently engaged the attention of Mr. Murray, F.L.S. In this remarkable flower, which refuses to open during cloudy or gloomy weather, there are two glands, sufficiently conspicuous, from which a secreted liquid, perfectly limpid and colourless, is incessantly distilling, day and night, for the space of about three days, when the temperature of the air is considerable. The discharge is from the tips of the glands into the labellum or pouch, and as soon as it reaches a certain level, the superfluity flows away by means of certain ducts provided for that purpose. By the test of permuriate of iron, and chloride of gold, conjoined with potassa, the presence of morphia was ascertained; and other tests, with litmus paper, determined it was a super-salt of morphia.-Dr. Edward Turner having stated that the liquid in the ascidium of the Pitcher-plant, yielded, on evaporation, crystals of superoxalate of potassa, Mr. Murray states that in the very considerable number of analyses which he has made of the liquid abstracted from unopen Ascidia, or Pitchers, lime-water and chloride of platinum gave him indications of neither the one nor the other of these ingredients. Muriate of soda, malic and other acids, and chromule, were the exclusive contents of the liquid of the Pitchers. When the lid of the Pitcher opens, a more decided degree of acidity, is soon manifested, from the contact of the atmosphere.

In the 3rd vol. of Audubon's highly interesting Ornithological Biography, the following passage occurs at p. 361 :-" On opening several individuals [of the Pied-billed Grebe, Podiceps Carolinensis] in different parts of the Union, I observed in their gizzards a quantity of hair-like and feather-like substance for which I could not account; but which I at length found to be the down of certain plants, such as thistles, the seeds remaining undigested and attached to it. My friend, Thomas Mac Culloch, made the same observation, on examining some at Pictou, in Nova Scotia, and I have found similar substances in the stomach of many individuals of Podiceps cristatus." In the description of the Rednecked Grebe, (P. rubricollis, Lath.), in the Ornithological Dictionary, Montagu says:-" Upon dissection, the stomach was found to be distended with feathers and small seeds. Being struck with so singu

lar an appearance, it was carefully washed and dried, and the contents of the stomach was, by that means, discovered to be feathers collected from its own body. For what purpose could such a quantity have been swallowed? Few of the piscivorous birds disgorge the refuse, like the Falcon family; and such a quantity can scarcely be supposed to have been taken into the stomach in the act of cleaning and dressing its plumage, unless they had been long collecting, and were impassable: many indeed were completely comminuted, and fit to pass into the intestines. This singularity has been observed also in the Crested Grebe." Now it would be difficult, nay impossible, to account for the circumstance of so great a number of feathers having been found in the intestines of a bird; and it appears to me the more likely to be the down of plants, from the fact of Audubon, as well as our own zealous Ornithologist, having discovered the feathery substance in the Crested Grebe. In future, the gizzards of the Grebes, and especially of the Crested species, should be examined with the greatest care.

In the same volume, speaking of Bewick, the great wood-engraver, Audubon says:-" He was a tall stout man, with a large head, and with eyes placed farther apart than those of any man that I have ever seen.”—p. 300. I think that, were there no other facts in support of Phrenology, the above would at once settle the doubts of all sceptics, as to the truth of that invaluable science for the organ of Form is indicated by the breadth between the eyes, or, which is the same thing, by the breadth of the bridge of the nose; and it may be imagined that Bewick possessed this faculty in a most wonderful degree. N. W.

TEMPERATURE OF STEAM. It is generally known that steam under pressure, is considerably higher in temperature than steam under ordinary circumstances; and that if such steam be allowed to escape into the atmosphere, its temperature is reduced, by expansion, so much below the boiling point, that it will not scald the hand when introduced into it near the aperture from whence it escapes. A portion of this rarified steam, however, instantly condenses, and, by giving up its latent caloric to the remainder, raises the temperature to the boiling point; so that, at a short distance, it will scald like the most vulgar tea-kettle steam that was ever generated. Paradoxical as it may at first appear, it is nevertheless true, that if highpressure steam, at 270 or 280, be allowed to expand suddenly, the hand may be borne in it, so much will the temperature be reduced: but after this steam has traversed a hundred feet of iron pipes and lost a considerable part of the heat which it originally contained, the portion which issues at the termination will be 212o, and will scald severely. B.

CHLORIDE OF SODIUM DECOMPOSED IN THE STOMACH. It has been long known that bile contains a considerable quantity of soda, and it has been generally admitted that the source from which it is derived is the muriate of soda taken in the food. It is, therefore, singular that no inquiry was ever instituted, as to the mode in which the muriatic acid was disposed of. It is now satisfactorily proved that the stomach secretes this acid in considerable quantities. No cause can be asigned adequate thus to effect the decomposition of muriate of soda, excepting the operation of that mysterious agent, which, in living bodies, seems to set at nought all those laws of chemistry and mechanics which operate on inert matter, yet which, could we investigate its mode of action, would be found strictly to conform to them. B.