Chapter XI: Letter XIX: gives a definition of the ellipsis, which would be a (5)

In respect to the connexion of the events of the Jewish and Egyptian histories, the period between the expulsion of the Phœnicians and the reign of Sesostris possesses a peculiar interest, as being that of the residence of the Israelites in Egypt, and of the Exodus. In the history of Josephus, we have an extract from Manetho, in which this latter event is expressly stated to have taken place under the father of Sesostris, a king whose name, in Manetho’s list, is Amenophis, (the third of that name,) and on the monuments Ramses. The date which chronologists are generally agreed in assigning to the Exodus is 1491; that of the termination of the reign of Amenophis, according to Champollion, is 1473, or, if the correction of his chronology which we have suggested in a note be just, 1478: it is singular that the difference of thirteen years (between 1491 and 1478) should be precisely the duration of a very suspicious interval which Manetho states to have taken place, after Amenophis had gone with his army in pursuit of the Israelites; and during which interval neither the king nor his army returned to [p187] Egypt, but are stated to have been absent in Ethiopia. If the Exodus occurred during the reign of any of the kings of the eighteenth dynasty, it could only have been in the reign of the immediate predecessor of Sesostris; since his conquests in Phœnicia, and his expeditions against the Assyrians and Medes, must have brought him in contact with the Israelites, had they been then residing in the Holy Land, so as at least to have caused some mention to have been made in their history of the passages of so great a conqueror. But presuming Amenophis, father and predecessor of Sesostris, to have been the Pharaoh of the Exodus, the wandering of the Israelites in the desert for forty of the fifty-five years ascribed to the reign of Sesostris, is a sufficient explanation of his being unnoticed in the Jewish history; whilst the fact of that nation having been subject to the Egyptians during the reign of Ousirei, commencing 124 years before the death of Amenophis, is attested by the paintings on the wall of one of the chambers of the tomb of that king, discovered by Belzoni, and with which we are so well acquainted by means of the model exhibited in England.

Whilst recalling to recollection the peculiar physiognomy of the Jews pourtrayed in that tomb,—and which is as characteristic of their present physiognomy as if it had been painted in the present age, instead of above 3000 years ago,—the equally well characterized, but very different physiognomy of the Phœnician shepherds, represented on the monuments of the same period, is decisive of the error of Josephus, who imagined the Jews and the Shepherds to be the same people. The Phœnician shepherds, long the inveterate enemy of the Egyptians, form a leading feature as captives, in the representations of the exploits of the monarchs who conducted the warfare against them. These people are always painted with blue eyes and light hair; and it is not a little curious to see assembled on the wall of the same apartment, different races, so distinctly characterised as the Jew, the Phœnician, the Egyptian, and the Negro; the latter in colour, and in the outline of the features, in painting and in sculpture, precisely as at present; all, moreover, inhabitants of countries not very distant from each other, and at a period when not more than twelve or thirteen centuries had passed since all these races had descended from a single parent. In the writings which attempt to explain from natural causes [p188] the diversity of race amongst mankind, much power has been ascribed to the effects of time and climate: but the facts with which we are now becoming better acquainted than before, do not appear to admit of explanation from those circumstances. It is worthy of notice that the negro, and the light-haired and blue-eyed people, the two races who might be deemed at the greatest distance apart amongst the varieties of man, are, equally with the intermediate Egyptians, the descendants of Ham.

Of the succession of kings in Manetho’s chronology, from Sesostris to the Persian conquest, a space of nine centuries and a half, about one half the names have been already identified on different monuments: four of the Persian monarchs, subsequent to the conquest, have also been traced in inscriptions in phonetic characters; their names are written, as nearly as can be spelt with our letters, Kamboth, (Cambyses); Ntariousch, (Darius); Khschearscha, (Xerxes); and Artakschessch, (Artaxerxes.)

The ascent by monumental evidence to yet more remote antiquity than the expulsion of the Phœnician shepherds, (B.C. 1822), is not altogether without hope, notwithstanding the general demolition of the temples of the gods, which took place according to Manetho, during the long dominion of the Phœnicians in Egypt. We learn from the _Description de l’Egypte_ that even the most ancient structures at Thebes are themselves composed of the debris of still more ancient buildings, used as simple materials, on which previously sculptured and painted hieroglyphics are still existing; these are doubtless the remains of the demolished temples, but the inscriptions will require to be studied on the spot. There is also reason to believe, that there exists amongst the ruins of the palace of Karnac, a portion of still more ancient construction than the palace itself; which, having escaped demolition, was incorporated with the more recent building. The inscriptions on this apparently very ancient ruin present the name and title of a king, which form a very interesting subject for future elucidation. The title does not accord with any one now extant on the table of Abydus, but possibly may have been one of those which were destroyed with a portion of the wall, and which are of kings of earlier date than the expulsion of the shepherds. The name is Mandouei, which name occurs in the dynasty anterior to Sesostris, but coupled [p189] with a different title, an effectual distinction; nor does the name recur in any subsequent dynasty. M. Champollion Figeac has, with much ingenuity, shown the probability of the identity of the Mandouei of the ancient ruin with the Osymandyas, Ousi-Mandouei, mentioned by Diodorus Siculus as an Egyptian king greatly distinguished by his conquests, whose reign M. Champollion infers, from the historical passages relating to him, to have commenced 190 years before the Phœnician invasion, or B.C. 2272 years; a prodigious antiquity, and of the very highest interest should it be established, since there exist of this individual no less than three statues in European collections, distinguished by the same name and title: two of these are colossal, one at Turin, and a second at Rome: a third is in the British Museum; and as all particulars must interest which relate to a statue, of which there is at least probability that is the most ancient existing in the world,—the date attributed to it being earlier than the birth of Abraham,—we copy from Burckhardt the following short description of its discovery: “Within the inclosure of the interior part of the temple at Karnac, Belzoni found a statue of a hard, large-grained sandstone: a whole length naked figure sitting upon a chair with a ram’s head upon the knees: the face and body entire; with plaited hair falling down to the shoulders. This is one of the first, I should say, the first Egyptian statue I have seen: the expression of the face is exquisite, and I believe it to be a portrait.”—(J. L. BURCKHARDT, _Travels in Nubia_, lxxvii. _Letter to Mr. W. Hamilton, 20th February, 1817_.)—This statue is in the farthest corner on the right hand side after entering the gallery of the Egyptian antiquities in the British Museum; and compared with other statues in the same gallery, which are of kings of the eighteenth dynasty, the dissimilarity of the features from the very characteristic ones of the latter family is too striking to be questioned. The problem of the age of this king Mandouei is, at all events, a highly curious one; and will probably receive its solution amongst the many other valuable discoveries which cannot fail to result from M. Champollion’s projected visit to Egypt, in which he will be accompanied by the sincere good wishes of every one in every country, who feels an interest in the restoration of authentic history.

E. S.

FOOTNOTE:

[33] It appears to us that a slight inaccuracy has crept into the deduction of all the dates in M. Champollion’s Chronology subsequent to the expulsion of the shepherds. The date of that event is the foundation of the subsequent dates, and is supposed to have taken place B.C. 1822; after which, according to the extract of Manetho in Josephus cited by M. Champollion, Thoutmosis, the king by whom they had been expelled, reigned 25 years and 4 months, followed by the other kings of the eighteenth dynasty, making altogether 342 years and 9 months: (including the 2 years and 2 months additional of Horus, in compliance with the version of the passage in the Armenian text of the Chronicle of Eusebius.) This number, 342 years and 9 months, falling short of the 348 years attributed to the eighteenth dynasty in Eusebius and Syncellus, M. Champollion has suggested that Thoutmosis may have reigned the five years which constitute the difference, before the expulsion of the shepherds, since, according to the record, he did reign, some years before that event, over all the parts of Egypt not possessed by the shepherds. So far, so well: but in such case, the year B.C. 1822, being the epoch of the expulsion of the shepherds, and not of the commencement of the eighteenth dynasty, must surely correspond to the fifth year of the reign of Thoutmosis, and not to the first, as M. Champollion makes it. We have hesitated to venture this remark on a matter to which M. Champollion must have given much attention, believing that mistake in us is much more probable than an accidental inadvertence in him; but we have returned frequently to the consideration, without having been able to satisfy ourselves; and the rectification of our mistake, if it is one, may prevent others falling into the same. [p190]

_Proceedings of the Horticultural Society_.

_June 19th_.

At this meeting a paper was read from the President, T. A. Knight, Esq., upon the culture of the mango and cherimoyer. Its object was to suggest some improvements in the management of these and other trees cultivated in stoves, deduced from an application of Dutrochet’s electrical theory of vegetation to practice. It has now become generally known that this observer is of opinion that the motion of the fluids in plants depends upon two currents of electricity, setting with very unequal force between the denser fluid of the tree and the lighter fluid of the soil in which the tree is planted; the more powerful current setting from the latter to the former, and so producing absorption, by conveying aqueous particles into the roots, through the vegetable membrane of the epidermis. In applying this theory to practical purposes, Mr. Knight recommends that the pot in which the cherimoyer or mango is planted, should itself be surrounded by a medium through which an equable and regular supply of fluid may be conveyed to the roots, and that the naked surface of the pot should by no means be exposed to the free action of the atmosphere. Without entering upon any question of the accuracy of the French philosopher’s observations, it is quite certain that such a mode of cultivation is that which is most congenial to plants, and which is indispensable to those of a habit at all delicate. The common practice of plunging pots into a tan-bed, or among sand, if in glass-houses, or in the earth if in open borders, is a proof of the necessity that gardeners have found, of securing as regular a temperature and degree of humidity as is possible for the outside of their flower-pots; through the pores in which, moisture is chiefly conveyed to the roots, which always cling to the inside surface of the pot.

Specimens of roses produced by branches budded upon the Rosa indica, were exhibited by Alexander Evelyn, Esq. We notice these not only on account of their extraordinary beauty, but also for the sake of recommending most strongly the adoption of the practice where delicate roses are found difficult of cultivation _per se_. If we consider what happens when the operation of budding, or grafting has succeeded, the reason of the advantage derived from such an operation will be apparent. When a bud of one variety is inserted under the bark of another variety, a union takes place between the cellular substance of the two; the bud is then placed in the same [p191] situation with regard to the stock, as the seed when sown is with regard to the earth. It immediately derives its nutriment from the ascending sap of the new tree, and begins to form its wood and branches, and to secrete its proper juices in proportion to the supply of food it now receives. If a plant from any cause produces roots with difficulty, its whole habit will be delicate, and its flowers if formed, will, as in the case of that most lovely of flowers, the double yellow rose, probably fall off without expanding, from the want of an adequate supply of nutriment from its roots; but, as in all trees, every bud is, when fully formed, in itself a perfect and distinct individual, if such an individual be removed from its own root, and placed where it will be supported by the healthy vigorous roots of another species of variety, which happens in budding, it will no longer have to depend upon a source, the supplies from which are imperfect, but on the contrary, like a seed removed from barren fertile ground, it will flourish in a degree before unknown. The contrary effect takes place when a vigorous plant is transferred to one less vigorous. And hence, the whole effect of stocks upon the scions, or buds inserted upon them.

There was also a great variety of fruit and flowers upon the table, and seeds of several useful vegetables were distributed.

_July 3rd_.

Seven medals were awarded to different individuals for fruit sent by them to the Society’s fête on the 23rd of June; and one to Capt. Drummond, for his “successful exertions in bringing living plants of the mangosteen from the East Indies.” A paper by the president was read upon an improvement in the mode of constructing hotbeds, but we despair of explaining it successfully without reference to figures. Among the display of fruits and flowers, which were exceedingly numerous, we were particularly struck by a collection of twenty-two varieties of strawberries from the Society’s garden.

Upon this occasion, thirty-nine new members were either ballotted for, or proposed, a striking proof of the estimation in which the Society is held by the public.

_July 17th_.

Upon this occasion, an enormous pine-cone from the River Columbia was exhibited. It measured 16-1/2 inches in length, and was stated to have been procured by the Society’s collector, Mr. David Douglas. Its seeds were represented to be as large as those of the stone-pine, and eatable. The tree is of the family of Pinus strobus, [p192] and will be an invaluable acquisition to our forests, if it should prove to succeed as well in this climate as in its own. We have already given some account of this plant in the last number of the old series of this Journal. The usual display was made of the finest fruit and flowers of the season.

_August 7th_.

A complete coloured set of the costly Flora danica was placed upon the table, having been presented by His Majesty the King of Denmark. An improved apparatus for fumigating hothouses was exhibited by its inventor, Mr. John Read: it consists of a brass cylinder, attached to the orifice of a pair of bellows, and fitted up with a chimney and draft-hole closed by a valve. The tobacco is put into the cylinder and ignited, and the blast from the bellows expels the smoke. The contrivance is ingenious enough, but while a hot-house fifty feet long, may be filled with smoke in ten minutes by means of a flower-pot, with a hole in its bottom, and a common pair of bellows, we cannot recommend any more expensive, and certainly less efficient apparatus.

The table was covered with a profusion of fruits and flowers.

_August 21st_.

The meeting-room this day exhibited a gratifying proof of the excellence of the productions of our English gardens. Of _flowers_, there were dahlias of the richest colours, and the most varied hues; some produced by plants that retain all their ancient stature, and others by dwarfs which seem to have lost nearly every character of the dahlia but its beauty. Of _fruits_, there were endless varieties of apricots, apples, pears, peaches, nectarines, grapes, pine-apples, and melons; one of the latter, from the garden of John Fuller, Esq., weighed thirteen pounds. The best apricot was the Moorpark; the best apple, the Duchess of Oldenburg, than which no princess has a fairer bloom, the best pear the Jargonelle, the best peach the Bourdine (forced), the best pine apple the Black Jamaica. We mention these as a guide to our readers, in their purchases of fruit-trees; for it is certain, that no greater service can be rendered to the public, than to point out the means by which they may avoid encumbering themselves with the polyonymous trash with which every nursery abounds. [p193]

MISCELLANEOUS INTELLIGENCE.

I. MECHANICAL SCIENCE.

1. _On the combined Action of a Current of Air and the Pressure of the Atmosphere_.—The phenomena observed by M. Clement Désormes[34], when a flat plate is opposed to air or vapour passing into the atmosphere from an aperture in a plane surface, have been rendered so easy of production by M. Hachette, as to be at the command of any person in any situation. M. Hachette has also accompanied the description of his instruments with elucidations, experiments, and philosophical reasonings.

The first simplification by M. Hachette was to make the nozzle of a pair of double chamber-bellows terminate in the middle of a flat plate; he found that when the bellows were worked, effects were produced opposite the jet of air of the kind described by M. Clement, disks of card and other substances being drawn towards the aperture against the direction of the current. At the same time that he described this experiment, he also announced his having produced the same effects by using a stream of water instead of a stream of air.

The apparatus was still further simplified, so as to make the stream of air from the mouth sufficient to produce the effect. A tin tube, A, _Fig._ 1, was soldered to the middle of a round tin plate, in the centre of which was a small orifice, E; three or four small projections of the tin, _f f_, were left at the edges of the plate, to prevent the disks of paper, card, or metal, from slipping off sideways. The figure is on a scale of one-half. Instead of the tin plate, a piece [p194] of smooth cork may be used, and for the tin tube, a glass tube, or one made by rolling up a piece of paper.

If the tube be held horizontally, or inclining a little upward, and a disk of card or paper be placed loosely against the aperture in the plate, it will be found that, on applying the mouth to the end of the tube, and blowing air through, that the disk will not be driven away, but actually made to apply closely to the surface of the plate; and if turned towards the ground it will be found to remain opposite the hole, and not to fall until the current of air is stopped. Even a plate of tin may in this way be suspended by a current of air; which at first would be supposed to conjoin with gravity in forcing it to the ground. When the disk is flexible and slightly elastic, a heavy sound, and sometimes even a shrill tone, is produced by the vibrations of the plate.

In explanation of this experiment, M. Hachette says, “The air is pushed from the mouth A of the tube, towards the orifice E of the plate; it strikes the part of the disk opposed to this orifice, and the mean pressure on that part is greater than the pressure of the atmosphere. The blown air then takes place of that between the plate and the disk opposed to it; it moves in this interval with a velocity decreasing from the edges of the aperture: the elastic force of this air decreases at the same time, so that its mean pressure between the plate and the inner face of the disk becomes less than the atmospheric pressure; and as this last pressure is exerted on the whole external face of the disk H, I, this disk, subject at the same time to the two contrary pressures on its opposing faces, obeys the greater, and is pushed towards the plate C D.”

“It is not necessary that the disk, C D, should be near the orifice E, of the tube A E. Let _Fig._ 2 be an instrument composed of a hollow cylinder, C D F G, and a flat border of the dimensions C″ F, or G D″. Let a tube, A E, be fixed to the bottom of the cylinder, the orifice E having a diameter of about three millimeters (0.12 of inch). If air be blown in at A, against the disk, H I, in the neighbourhood of the flat border, the disk will be urged towards the orifice E. This instrument is also delineated on a scale of one half. The disk, with the attached weight, weighs about 12 grammes (184.87 grains), being 54 millimeters in diameter; the pressure of the atmosphere upon it equals 23 kilogrammes: from which it follows that, in this experiment, the pressure of the air blown upon the inner surface of the disk, and the atmospheric pressure exerted on the exterior of the same disk, only differs from each other by about one two-thousandth part of the latter.”—_Annales de Chimie_, xxxv. 34.

FOOTNOTE:

[34] See the last volume of this Journal, p. 473.

2. _Considerations relative to Capillary Action, by_ M. Poisson.—M. Dutrochet, whilst explaining his views relative to the cause of vital movement in plants and animals, stated that if an animal or vegetable membrane were formed into a bag, having a tube of [p195] glass attached to its aperture, and were then filled with a liquid substance, having a strong affinity for another liquid, into which the bag was to be immersed, it would not only have the power of absorbing the latter liquid into its pores, but also, in certain cases, of forcing it up to the top, and even out of the glass tube held in a vertical position. On this point, a difference of opinion with regard to the force of capillarity took place: M. Ampère maintaining that capillary action would raise the fluid to the top of the tube, but not cause its expulsion; while M. Poisson maintained that, in certain cases, the latter effect could be produced. The latter has since then published a note, which we transcribe in part, from the _Annales de Chimie_, xxxv. 98.

Suppose that two different fluids, A, B, are contained in a vessel, and separated the one from the other by a vertical division; the heights being in an inverse ratio to the densities, so that the points, _a_ and _b_, in the two faces of the division, and situated in the same horizontal plane, shall support equal and opposite pressures: suppose also that the division is pierced with one or more holes of small diameter, or, in other words, that it is traversed by several very narrow canals, as _a_, _b_, perpendicular to the two faces, and which may be regarded at first as filled with air, or any other fluid.

If the substance of the division exerts upon each of the two liquids an action superior to the half of that which the liquid has upon itself, each liquid will enter into the canal _a_, _b_, just as it would rise above its ordinary level in a capillary tube of the same size and substance. It would also be urged, by the excess of pressure which it would exert at the extremity of the canal, against the elasticity of the included air. When the two fluids have penetrated the interior of _a_, _b_, the air will be pushed on both sides in different directions by forces each of which is equal to the primitive pressure augmented by the corresponding capillary force, _i. e._ augmented by forces proportional, according to the known theory of M. Laplace, to double the action of the tube on the liquid, less the proper action of the liquid itself. It will only be in the case when the capillary force shall be the same on both sides, that the air, after being compressed to a certain degree, will remain at rest: for whenever this force preponderates at one end of the canal, the air will be driven out at the opposite end, and the liquid with the strongest capillary attraction will entirely fill the canal.

Suppose this liquid to be A, then let us consider the forces which will act on the portion _a_, _b_, of this liquid. At the extremity _a_, it will be submitted to the attraction of the exterior fluid A: at the extremity _b_, it will be attracted in the opposite direction by the liquid B. Now the two liquids being different, their attractions will be unequal, and we will suppose that that of B, on the matter [p196] of A, is greater than that of A for itself. As to the action of the canal on the portion _a_, _b_, that will be equal, and exerted in contrary directions at its two extremities; it will not, therefore, be either adverse or favourable to the movement of the fluid in the canal: and the same will be the case with respect to the pressures exerted at _a_ and _b_, by the external liquids, as long as they are equal: nevertheless, the action of the canal, and the external pressures, will prevent the thread of fluid from being broken, so that it will move without interruption in the direction in which it is drawn by the greatest attraction, or from _a_ to _b_. Hence will result an elevation of the level of B, and, consequently, an increase of pressure at the extremity _b_, of the passage, and this elevation will proceed until the difference of pressure in _a_ and _b_ shall be equal to that of the attractions exerted by the two fluids A and B, on the thread _a b_; this effect will be produced the more rapidly as the division is pierced with a greater number of passages similar to that which has been considered.

Now let us examine what would occur if the division were formed of two others different in their nature, and exactly superposed; exerting no action on one of the liquids, B for example, and one only acting on the other liquid. The liquid B will then retain its original position undisturbed; in consequence of the action it exerts upon itself it cannot penetrate the canal _a b_, just as mercury cannot escape by a capillary aperture made in a barometer-tube. It will be the same with A, when that face of the division which exerts no action upon the liquid is turned towards it; so that how numerous soever the apertures, the two liquids would, under such circumstances, remain separate and preserve their original level. But if the division be turned so that the face which acts upon A shall be in contact with that liquid, it will penetrate the canal _a b_ by means of capillary attraction; and the velocity which the liquid urged by this force may acquire, may make it pass that point in the canal where the division changes its nature, and even make it reach the extremity in the liquid B, so that it is possible that the liquid A should entirely fill the canal _a b_, as in the case which has already been examined. Then if we always suppose the attraction of B for A to be superior to that which A has for itself, the thread _a b_ will flow into B until the level of the latter is so far altered that the excess of pressure at _b_ can balance the difference of attractions exerted by the two liquids at _a_ and _b_.

M. Poisson then observes that, without pretending to assign a cause, exclusive of all others, for the phenomena of absorption by vegetable and animal membranes observed by M. Dutrochet, his object is to show that effects which have at least a great resemblance to these important phenomena, may be produced by capillary action conjoined with the difference of affinity existing between heterogeneous substances without the assistance of electricity, either moving or quiescent. It appears that M. Dutrochet afterwards [p197] found mineral substances, as a piece of slate, might be substituted for the organized tissues; this being the case, the opinion which refers such effects to a general cause, as capillary attraction, acquires more probability.

3. _Novel Use of the Plough_.—Mr. Bruckmann states that he has long thought the plough might be used in levelling roads and clearing the foundations for fortifications. In 1824 he had an opportunity of applying it in the construction of a canal required to furnish a motive force for the service of the rock-salt works of Friedrichshall. The bed was to have a section of 700 square feet, and it had been calculated that the excavations would require 200 men for two years, whereas the king of Wurtemburg wished it to be done in one year from the spring of 1824.

Three ploughs were employed; the first had two handles, a coulter, and a share, the latter being in the form of a wedge. This plough was preferred in the beds and gravelly grounds; and it was found advantageous to give it an oscillatory movement by the handles during its progress. Drawn by eight horses, it could turn up 25,000 cubic feet of an argillaceous soil, in three hours; with ten horses it turned up 19,800 cubic feet of a gravelly soil, in the same time. This plough was tried in 1815, against fifteen others of the ordinary kind, in the construction of a watercourse for a mill; all the fifteen were quickly broken by the work.

The second plough had two handles and a coulter, but the share had only one cutting edge, which was rounded and with an ear. It was made five times as strong as an ordinary plough, and succeeded well in compact and argillaceous soils, where, with eight horses and four men, it moved 48,000 cubic feet of earth in three hours. In case of fracture ten minutes sufficed to change the coulter and share, and, during the work, 2,300,000 cubic feet of earth were loosened by it.

The third plough was smaller and lighter, it had two handles, a coulter, an ear, and a share, the latter lance-shaped. It was used for excavating the sides of the canal, on which the horses attached to the first plough found it difficult to walk because of the inclination. It was worked by ten or twelve men.

To establish an accurate comparison between the work of these ploughs and that done by the pickaxe and spade, a piece of ground was wrought solely in the latter manner by six strong working men. The result of a long trial was the breaking of 150 cubic feet of ground by each man in nine hours. Comparing this result with the work of the ploughs, the following are the results:—The first plough did the work of 477 men, the second of 960 men, and the third that of 50 or 60 men. The canal was finished on April 30th, 1825, the ploughs having saved 32,000 days, according to the work-day of a labourer.—_Bull. Univ._ D. vii. 343. [p198]

4. _Discovery of Rocks under the Surface of the Sea_.—The fishers of the Mediterranean use an apparatus for the discovery of rocks beneath the surface in those places where they wish to cast their nets, which supplies, in a great measure, the insufficiencies of the ordinary means of taking soundings. The method consists in carrying a long and thin cord over the bottom to be examined, and which, when it meets with an obstacle, is stopped by it and becomes folded in the place where it occurs. It will easily be understood, that when a cord has been carried over a certain space without meeting with any resistance, that proof is obtained of the non-existence of rocks or other obstacles, at a depth less than that to which the cord has been sunk; and as the examination can easily be carried on to 100 feet below the surface, it may be said that, wherever such an apparatus has passed unimpeded, the navigation is free. If, on the contrary, some isolated rocks are found during the examination, the place where the cord becomes doubled points out the locality, which may then be determined more accurately by other trials, and the summit and neighbourhood of the submersed rocks be accurately examined by means of soundings.—_Annales Marit._; _Bull. Univ._ F. viii. 44.

5. _Paper to resist Humidity_.—This process, which is due to M. Engle, consists in plunging unsized paper once or twice into clear solution of mastic in oil of turpentine, and drying it by a gentle heat. The paper, without becoming transparent, has all the properties of writing-paper, and may be used for the same purposes. It is especially recommended for passports, workmen’s books, legal papers, &c. When preserved for years it is free from injury, either by humidity, mice, or insects. It is further added, that a solution of caoutchouc will produce even a still better effect.—_Kunst und Gewerbe-blatte_.

6. _Professor Amici’s Microscopes_.—This distinguished personage has lately exhibited to the _savans_ of this country two microscopes of his own workmanship,—an achromatic refractor, and a reflector of his own particular invention. The object-glass of his refractor is of a very complicated construction, and is composed of three double-object glasses combined together in the space of about an inch. The flint-glass from which his concaves are formed is of the manufacture of Frauenhofer; his convexes are of Dutch plate, crown-glass, and French plate, separately. Each object-glass detached has but a small aperture, and is of long focus; but when the three are combined together, the angle of aperture is very considerable, and the focus short. By this ingenious arrangement the trouble and difficulty of manipulating deep single-object-glasses of large aperture is avoided; but advantages gained one way, in practical optics, are generally lost in another, and the twelve surfaces of the objective produce a kind of softness and muddiness in [p199] the image strongly contrasted by the effect of a good single triple-glass of equivalent power. When, however, only two of the object-glasses are combined, the effect is very fine. Between the object-glass and eye-glasses is placed one of those prisms originally invented by Sir I. Newton to act as an eye-piece of his telescope, and of which a description may be seen in his correspondence at the end of Dr. Gregory’s Optics. The utility of the introduction of this device appears very questionable in an instrument already so complicated. The diversion of the rays into a course at a right angle to their original progress (merely to give an horizontal instead of a vertical position to the body) is surely no warrant for the employment of two extra refracting surfaces and one reflexion, which cannot fail to have a pernicious influence on the formation of the image. An horizontal position of the body is attained with the utmost facility by a proper construction of the mounting, &c. Setting aside the dulness of the image produced by the numerous refractions, the performance of the instrument on test-objects was highly respectable and satisfactory.

The reflector is a modification of the original construction recommended by the Professor, who seems to have profited by the schooling he received from Dr. Goring, and now sails much closer to the wind than he did. His objective metal is now two inches focus, with an aperture of 1-1/2 inch; but half an inch is cut off for the purpose of preventing the bad effect of the marginal rays, so that only 1 inch of the central portion of the metal is employed;—the diameter of the diagonal mirror is also reduced to its proper standard, by which means the blot in the centre of the visual pencil is rendered as small as possible. It may be asserted of this instrument, that it does as much as can possibly be expected from an objective part of 2 inches focus, showing many test-objects faintly, and with much effort; but it is totally unable to compete with deeper ones equally perfect and of the same angular opening. The Professor has, in some of his instruments, reduced the focus of the elliptic metal to 1-1/2 inch, and will, no doubt, gradually slide into the adoption of that radical reform in his instrument, so happily carried into effect in this country by Dr. Goring, in conjunction with Mr. Cuthbert,—at least if the figuration of elliptic metals of 3/10 inch focus with 2/10 inch of aperture shall not surpass his powers of execution. During the Professor’s stay in this country there was a grand field-day at his hotel, at which _both his microscopes were tried against the Goringian modification of the reflector, the superior weight of metal of which completely beat every thing opposed to it_. For the honour of the Professor it must be stated, that he admitted this defeat with great candour and good sense, and even had some difficulty in believing in the identity of some of the objects used, so differently was the ordinary apparent structure developed by the English improvements on his instrument. It may with safety be averred that no refractor, at least, will ever be [p200] made to surpass _Dr. Goring’s improved Amician Engiscope_; and it seems equally certain that no other reflector will ever be invented capable of the same facilities of application to the examination of both opaque and transparent objects. If Professor Amici has been beaten, it has been done with his own weapons,—the copy has surpassed the original,—the child, by virtue of foreign nursing and tuition, has exceeded the stature and strength of the father.

II. CHEMICAL SCIENCE.

1. _On the Specific Heat of Gases, by_ MM. de la Rive _and_ Marcet.—The principle on which these philosophers proceeded in their researches, was, to expose equal volumes of different gases to an equal source of heat during equal times, and to judge, by the augmentation of elastic force in each gas, the temperature which it had acquired. The apparatus was a kind of manometer, and consisted of a glass balloon to retain the gas, and a bent tube attached to it, which, descending into a vessel of mercury, served to show, by the column of metal within it, what was the elasticity of the gas. This method was adopted, because, i. The gas was not altered in volume by the change of temperature, its elasticity only changing: ii. The temperature was indicated by the gas itself, and not by a thermometer: iii. Water was easily separated previously from the gases, and excluded from the apparatus: iv. All the gases were placed in exactly the same circumstances, so as to render it unnecessary to refer to any calculation for the purpose of comparison.

Two methods of applying heat were resorted to: in one the balloon, containing the gas at a certain temperature, was placed in water at a higher but constant degree, for a certain time (generally 4′), and the elevation of temperature noticed: in the other, the balloon with the gas was inclosed in a larger copper balloon, blackened inside, and the space between the two exhausted as much as possible of air; the apparatus being then immersed in warm water, the heat gained access slowly to the gas, and the time of each experiment was increased, at the same time that certain sources of error were avoided.

The gases experimented with were, atmospheric air, oxygen, azote, hydrogen, carbonic acid, olefiant gas, oxide of carbon, nitrous oxide, nitrous gas, sulphuretted hydrogen, ammonia, sulphurous acid, muriatic acid, and cyanogen. Great care was taken in their preparation. The result of the experiment was very unexpected; for, during the five minutes allotted for each, all had acquired the same temperature,—a circumstance which proves that they all have the _same specific heat_. The equal volumes of gas at the pressure of 65 centimeters (15.59 inches) and the temperature of 20°C., being exposed to a source of heat at 30° C., acquired a mean temperature of 6.32 degrees in five minutes, the extreme difference, in any of the experiments, not being more than 0.04 of a [p201] degree. One gas only forms an exception to the above statement, namely, hydrogen, which was always heated more than the others, namely, to 6.6 degrees in the five minutes. This effect is considered as due not to any difference in specific heat, but to a difference in conducting power.

Experiments were then made with dilated gases, to ascertain whether dilatation caused any change in capacity, and it was found to diminish slowly but regularly with the diminution of pressure. These results, with a third which is also interesting, have been thus generally expressed by the authors at the end of their memoir.

i. All gases in equal volumes, and at the same pressure, have the same specific heat.

ii. Other circumstances being the same, the specific heat of gases diminishes with diminution of pressure, and equally for all the gases: the progression converges slightly and in a ratio much less than that of the pressures.

iii. Each gas has a different conducting power, _i.e._, all the gases have not the some power of communicating or receiving heat.—_Ann. de Chimie_, xxxv. 5.

2. _On the Incandescence and Light of Lime_.—The experiments made by Lieutenant Drummond upon the light of lime and other earths when highly ignited, with the highly interesting application which he has made of that emitted from lime, to the purpose of geodesical surveys, has induced M. Pleischel to repeat and vary the results. He states that the utmost light is given by lime; the earth being pulverised and exposed on burning charcoal to the heat excited by a jet of oxygen falling upon it. He endeavours to account for the effect, by supposing a kind of pulverulent atmosphere disengaged from the lime at the high temperature used, and considers that the substances which are competent to emit molecules only in the gaseous state, cannot produce this intense light.—_Zeitschrift für Physik_, &c.

3. _Evolution of Heat during the Compression of Water_. May 14, 1827.—M. Arago announced to the Academy of Sciences, that M. Despretz had ascertained experimentally, that the compression of water by a force equal to 20 atmospheres, caused the disengagement of one sixty-sixth part of a degree of heat.

4. _On Electrical Excitation_.—M. Walcker affirms positively from experiments made with great care, that three bodies of different exciting power are necessary, in every case of excitation of electricity by contact, and that all the phenomena of this kind are subject to this condition. If, for instance, two portions of the same metal being put in contact, electricity is produced, it is because there are three different states of temperature brought into play, one being the result of the other two, and a mean between them. One fact which more than any other sanctioned this idea, was, that the electric [p202] currents were the more apparent as this third state of temperature was made more sensible.—_Bull. Univ._, A. vii. 374.

5. _Magnetic Repulsion_.—A very remarkable result has been obtained by M. Becquerel, from the use of an extremely delicate magnetic arrangement, which he has for the present called a _sideroscope_. Its use is exactly the same in principle as that of the magnetic needle, indicating iron, for instance, by the attraction manifested; but it is so delicate that it will show it in the most minute quantity possible, as, for instance, in gold, silver, or copper money, innumerable minerals, &c. This instrument shows no magnetic power or attraction in gold, silver, copper, palladium, tin, lead, zinc, or brass, when chemically pure, and a great many vegetable and mineral substances have no action on it: but the most curious result is, that very pure bismuth and even that of commerce has a _repulsive_ power, which, if it be found ultimately to be independent of any magnetic _polarity_, is the first fact of the kind that has been made known. Antimony also presents the same phenomenon.

6. _Diminished Solubility of Substances by Heat_.—Mr. Graham has added one to the few facts of this kind with which we were acquainted, and has accompanied its description with some very interesting considerations, which may be found at length in the Philosophical Magazine, N. S., ii. 20. The salt experimented with by Mr. Graham is the phosphate of magnesia; which may be prepared by mixing a solution of 21 parts of phosphate of soda with one of 15.375 parts of sulphate of magnesia: within 24 hours the phosphate of magnesia precipitates in acicular crystals; they should be agitated with repeated portions of water, then thrown upon a filter with more water, and left to dry.

Solutions were obtained by occasionally agitating this salt with water in the proportion of 2 ounces to a pint of the fluid, for four days; being then decanted and filtered, they had a sweetish taste. A quantity of this fluid being heated in a water-bath, became turbid before the temperature had attained 120° F.; at 212° a cloudy precipitate slowly subsided, and the supernatant fluid became nearly transparent. The precipitate was found to be anhydrous phosphate of magnesia; and, by further experiment, the difference in solubility was found to be such, that water at 45°, dissolving 1/744th part its weight of the anhydrous salt, water at 212° only dissolved 1/1151th part. When in the state of crystals, or as hydrate, the proportions of salt were 1/322 and 1/498 to 1 of water.

Mere continuance of the heat had no effect in increasing the precipitate either of this salt, or from aqueous solution of lime, provided no part of the solution was at any time converted into vapour; but if the solution only occupied a small part of the vessel, and ebullition came on, then, although all the water might be returned to the solution, yet the precipitation went on, and might be [p203] increased _ad libitum_, particularly in the case of lime water. The cause of the precipitate appears to be the same in all these cases. The moment a drop of the solution is converted into vapour, it deposits the quantity of lime or salt which it held in solution; and in the case of bodies which dissolve so sparingly and with so much difficulty, although the water be returned again to the solution, it is incapable of re-dissolving what it has deposited. We know that it would be a hopeless task to form a saturated solution of lime by agitating with the water no more than the few grains which it is capable of dissolving; and in the case of ebullition, when the lime is once deposited, there should be the same difficulty in taking it up.

Mr. Graham states that he has observed this effect not only in lime-water and in solution of phosphate of magnesia, but to a certain extent in all bodies of difficult solubility, in the sulphate of lime, for instance, even when greatly diluted; and he believes that the deposite from slight boiling observed in many mineral waters, and generally attributed to the dissipation of carbonic acid gas, depends, in some instances, upon this cause. However weak the solution may be, it is evident that a portion of the salt may be deposited in this way.

7. _On the Composition of Cyanic Acid_.—M. Wohler some time since announced the production of cyanic acid, and cyanates, corresponding in composition to the substance presumed to exist in the fulminating compounds of silver, mercury, &c., the nature of which was made out by MM. Liebig and Gay Lussac. M. Liebig, upon repeating M. Wohler’s experiments upon his cyanate of silver, obtained only 71.012 per cent. of oxide of silver, instead of 77.23, which was the quantity present according to M. Wohler’s analysis, and concluded that the acid was the cyanous, and not the cyanic. The latter philosopher was consequently induced to repeat his experiments: one of his methods of decomposing the cyanate of silver was by muriatic acid gas: at first liquid cyanic acid forms, which is very soon transformed into a white crystalline mass; but, on continuing the operation, and applying a higher heat, a large quantity of muriate of ammonia and cyanic acid is evolved. This process indicated 77.5 per cent. of oxide of silver in the salt. Another process consisted in dissolving the cyanate in nitric acid, and precipitating the silver by muriatic acid, the result was 77.05 of oxide per cent. A third analysis, made by reducing the silver of the salt, gave a result of 77.35 per cent. oxide. The mean of these is 77.3, and the theoretical number obtained by calculation is 77.23, so that the acid appears to be truly the cyanic; and the curious fact of its being the same in composition with that in the fulminating compounds of silver and mercury, but very unlike in properties, still remains undisturbed.—_Bull. Univ._, A. viii. 53.

8. _Iodous Acid_.—According to M. Wohler, the iodous acid of [p204] M. Sementini[35] is nothing more than a mixture of chloride of iodine and iodine. When saturated with carbonate of soda, the iodine in solution is precipitated, and on evaporating the solution to dryness, and heating it strongly, the residue fuses, and by proper tests is found to be a mixture of chloride and iodide of sodium.

These statements apply only to the iodous acid: as to the oxide of iodine, no source of chlorine exists in the process last described by M. Sementini.

FOOTNOTE:

[35] See the last volume of this Journal, p. 477.

9. _On Manganesic Acid, by_ M. Unverdorben.—When manganesate of potash is distilled with a little anhydrous sulphuric acid, manganesic acid is evolved in the form of a red transparent gas, which dissolves in water, forming a red solution. The gas frequently decomposes spontaneously in the retort, with explosion, producing oxide of manganese and oxygen.

Manganesate of potash was analysed by distilling it with excess of sulphuric acid, collecting the oxygen disengaged, and estimating the proportion of protoxide of manganese and salts of potash remaining in the retort. According to these experiments the acid consists of

Manganese 58.74
Oxygen 41.26
------
100.00

And the manganesate of potash of Or being calcined
Potash 25.63 32.75
Manganese acid 52.44 67.25
Water 21.93 ------
------ 100.00
100.00
_Ann. des Mines_, 1827, p. 145.

10. _Heavy Muriatic Ether, and Hydrocarburet of Chlorine or Chloric Ether_.—Some comparative experiments have been made on these two substances by M. Vogel. He prepared the former of them by passing chlorine gas into alcohol. The muriatic acid was then separated by distilling the fluid from off chalk, in which operation the muriatic ether and alcohol passed over together, and these were divided by the addition of water, which dissolved the latter, and left the former. The chloric ether was made as usual from chlorine and olefiant gases. The results that were obtained by acting on these substances by a high temperature, potash, phosphorus, &c., induced M. Vogel to consider them as identical in composition, notwithstanding some differences in their physical properties; the specific gravity of the muriatic ether was 1.134, that of the chloric ether 1.214, and the odour of the latter is more aromatic, and the taste more sweet than of the former.

Whilst passing the chlorine into the alcohol, M. Vogel observed [p205] that if the sun shone upon the substances when the action was nearly complete, each bubble of chlorine as it entered the alcohol produced a bright purple flame, a dense white vapour, and caused violent concussions in the liquid; another curious instance, in addition to the many that are known, of the power of solar light over chemical action.—_Journ. de Pharm._ 1826, p. 627.

11. _Test for the Presence of Nitric Acid_.—The following method is one devised by Dr. Liebig, for the detection of this substance, which it will effect, he says, when there is not more than a four-hundredth part of the acid present. The liquid to be examined must be mixed with sufficient sulphuric solution of indigo to acquire a distinct blue colour, a few drops of sulphuric acid added, and the whole boiled. If the liquid contains a nitrate, it will be bleached, or, if the quantity is very small, rendered yellow. By adding a little muriate of soda to the liquid before applying heat, a five-hundredth of nitric acid may easily be discovered.—_Ann. de Chimie_, xxxv. 80.