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causes may tend to influence the equilibrium, the figure or motion, of the earth; these physical conditions, which had not been hitherto introduced into any theories of the globe, will throw light on different questions of geology and general physics.

The "Analytical Formula” of M. De la Place, have led to the following results. The couches or lays, at the greatest depths, are the most dense. These couches are regularly disposed about the centre of gravity of the globe, and they differ but little, in point of form, from that of a curved surface, formed by the revolution of an ellipsis. The density of the water is nearly five times less than the mean density of the earth. The heaviest rocks have not the mean density of the globe at large, and of course the interior couches are not of the same nature as the surface.

The presence and distribution of the waters on the surface of the earth produce no considerable change in the law of the diminution of the degrees, and in that of gravity or weight. Every geological system, founded on the bypothesis of any considerable displacing of the poles, at the surface of the earth, must be inconsistent with the mechanical causes now ascertained to determine the figure of the earth. The temperature of the globe has not, sensibly, diminished, since the time of Hipparchus, (more than two thousand years,) and the effect of this decrease of heat has made no variation in the whole of this time, in the duration of a day, the two-hundredth part of a centesimal second.

M. Girard has employed himself in investigating certain questions relative to cast iron, and the use of that mate. rial in machinery; also as to the conducting of waters, and to the coppers of steam-engines. The casting of iron may be readily adapted to the form which nature impresses on bodies, to render them capable of a determinate resistance, with the least possible quantity of resisting matter. And thus the figure of hollow pipes may be given to different mobile pieces of a machine, while casting, like to the stalks of certain plants, or to the plumage of birds. M. Girard, who is also author of an excellent "Treatise on the Resistance of Solids," deduces from his " Formula" the relation between the interior and exterior diameters of a hollow cylinder, so as to render the cylinder both lighter and more capable of resistance, in given

circumstances. The facts cited by the author, the details into which he enters relative to the operations of casting, and also to the means of augmenting solidity and producing uniformity there. in, are well worthy the notice and study of artists.

M. Dupin recited a report on the construction of carriages, and on the causes that render them most liable to be overturned. One of these, perhaps the principal, is neglecting the execu tion of the ordnances as to the loading of carriages. The conditions, or cases of stability of a carriage in motion, according to the nature, the inclination, and the greater or less perfection of the roads, are considered; but the reporter, without pointing out new forms or methods, lays down data to discover and ascertain them. He refers to the progress which it is natural to expect, from the growing improvement of the mechanical arts, applied to the construc tion of carriages. These are capable of being made lighter, without impairing their solidity, and better able to encounter hazards, without diminishing their firmness. Improvements, also, must be planned, as to the form, structure, and keeping up, of roads; and regulations must be rendered more efficacious to produce their effect.

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The author recommends to the government to propose a prize of twenty thousand francs, to be granted on the first of January 1825, to the constructor or coach-maker, that, without neglecting such qualities as are requisite in a public carriage, capacity, convenience, and lightness, should secure, also the greatest stability for the conveyance of a given number of passengers, with a determinate weight of baggage. It will require the experience of a year or two, to prove the goodness of such carriages. The plans of the carriages should be accompanied with a descriptive memoir, detailing the calculations as to stability. In a program should be accurately specified certain facts to serve as bases to the attempts of projecting mechanists, including fixed principles, from which the proportion of carriages may be derived, as also the best disposition of the loading, so as to acquire the greatest possible stability.

'The same reporter, as the organ or representative of the commission deputed to examine the work of M. Marestier, on steam-packets, and the military marine of the United States of America, detailed the contents of thei

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analysis. In this, the structure and the dimensions of steam-packets are investigated, as also the mathematical results deduced by the author, and his description of those of America. On the whole, the committee recommend to government to assist or contribute to the printing of the Memoir, as it has to the publication of several other works.

Some experiments made in Sweden, by M. Lagerhielm, communicated to the academy by M. Olivier, ancient pupil of the Polytechnic School, re. siding in Sweden, have been submitted to the examen of Messrs. Girard and Ampère. The subject treated of is the draining off water, by orifices made in thin sides of the receptacles containing it. The learned Swede proves that elastic fluids are, in this case, subject to the same laws as incompressible fluids, such as water.

M. Ampère presented a continuation of his Memoir on the Electro-Dynamic Phenomena. Herein he has confirmed, by new experiments, certain results deduced from his preceding “Formulæ;" he has also ascertained and announced two new facts. 1. That a voltaic conductor, placed very near a metallic circait inclosed (fermé) but not communicating with it, determines or draws an electric current to it. 2. That a circular conductor, forming an entire circumference, has no action to produce a revolution round its axis, of an inclosed conductor, be it of whatever form; and that the same property occurs in a conductor bent as the arc of any circle, whatever be the number of de grees of that arc.

To this succeeds an investigation of the electric currents in the interior of the globe, proceeding from east to west, and the more intense as they are nearer to the magnetic equator, which must then be considered as a medium direction between all the currents; these currents are considered, in all the circumstances of motion that they would produce on conductors, whether horizontal or vertical.

The results collected, by this author, are conformable to the numerous experiments already made; some by himself, others by M. Delarive, all of which tend to shew the action that the earth exercises on mobile voltaic conductors. The author has thus completed the theory of action which he had discovered between two conductors, and also that of the influence of the terrestrial

globe upon a condactor; a phenomenon which he was the first to observe.

In the limited state of human knowledge, it is not possible to ascertain the distribution of the electric currents of our globe, nor even to decide the ques tion of their actual existence. If it be admitted, we mast suppose one part of these currents to come very near the surface, as the direction of the magnetie needle is affected by the variations of the temperature from day to night. These variations, however, being scarcely perceptible, it is inferred, that the effects depend chiefly on the currents that prevail at great depths.

Another object of the researches of M. Ampère, is the assimilation that he makes of the magnet, and of the assem blages of circular parallel currents, to which he gives the name of electrodynamic cylinders. This assimilation may be manifested, either by the way of experiment or by calculation. Is employing the second method, we must compare the poles of the magnetised bars, and not their extremities, with the extremities of the electro dynamic cylinders; as, according to the experiment of M. Ampère, the magnetic poles disclose the same properties as the extremities of the electro dynamic cy linders. This kind of proof, while it confirms the results of experiment, impresses the character of theory on inductions derived solely from the observation of facts.

Two young and able naturalists have supplied what was wanting, in this respect, in the Tract of M. Ampère on the identity of magnetism and electricity. Their memoirs were read to the academy, in the sitting of February 3, last. That of M. Mont. Ferrand contains calculations relative to the mutual action of a rectilinear conductor, and of an assemblage of circular currents, situated in planes parallel to the direction of this conductor. Assuming the value or proportion assigned by M. Ampère, to the action of two ele ments of electrical currents, the author determines that which is exercised by an indefinite rectilinear conductor, J. On an element of electrical current. 2. On a circular current. 3. On an assemblage of similar currents, perpendicular to a right or curved line, passing through their centres. When this is a right line, the calculation_reproduces the law discovered in 1820, by M. Biot; and confirmed by the experiments pub

lished,

Fished, in the same year, by M. Pouillet. If the line is a circumference of a circle, we then find one of the results of the experiments of Messrs. Gay-Lussac and Welter, on a steel ring magnetised, by the process of M. Arago. If the line of the centres is only a curve, with two branches symmetrical, with respect to a plane passing through the conductor, the analysis leads to a result confirmed by recent experiments.

The second circular memoir is that of M. F. Savary; some account of it has already been given in the Revue Encyclopedique.

Never was any discovery prosecuted with more zeal and success than that of Erstedt, on the analogy between the electric and magnetic fluids. Three years have bardly elapsed, and the science has already arrived at certain theories, founded on facts, numerous and well analysed; also, at methods of calculation which would, alone, produce new discoveries.

While the knowledge relative to electricity and magnetism is acquiring daily accessions, the science of light and optics is advancing with rapid steps. M. Fresnel has presented several memoirs, the object of which is to express the general laws of double refraction; also to discover the laws of a new kind of polarisation, to which he has given the name of circular polarisation; also, to prove directly, that glass compressed, causes light to undergo a double refraction; and lastly, to examine the law of modification impressed by a total reflection on polarised light. These researches are connected with the theoretic notions that M. Fresnel, and several other writers on physics, have adopted, respecting the nature of light. They consider its action as operated by vibrations extremely rapid, propagated in elastic mediums. From this opinion not being generally admitted, some dissensions have arisen in the republic of sciences, though, from habit, more peaceably disposed than that of letters.

The minister of interior had desired the academy to examine afresh the question of areometers, and compare the respective methods proposed, so as to determine with precision, by means of that instrument, the specific weight of liquids. M. Arago, reporter to the commission charged with this labour, bas retraced some very accurate experiments already made, by M. GayLussac, therein completely answering MONTHLY MAG. No. 387.

the views of administration. M. GayLussac has drawn up tables, that for science and minute detail become the surest guide that rulers can follow in the collection of the revenue. A memoir of M. Francoeur, on this subject, and another by M. Benoit on areometers, have honourable mention in the report of the commission. The latter memoir may be considered as an excellent chapter of a treatise on physics; but the author has not taken up the experimental part of the question.

M. Despretz has applied himself to consider the conductibility of bodies, that is, the greater or less facility with which heat penetrates them, and spreads through their interior. He has found that, in their relation to this property, the following bodies or substances are in the order that experiment has ascertained, commencing with the highest degree; copper, iron, zinc, tin, lead, marble, porcelain, and brick-clay. The report on this labour was drawn up by M. Fourier. The results obtained by M. Depretz are pronounced by the commissaries to be every way worthy of the academy's encouragement; and that the physical sciences, several arts, and the oeconomical processes, as to the distri bution and use of fuel, would be benefited by their publication.

Of three comets observed in 1822, the first was discovered by M. Gambart, to whom we owe, also, the observation of two others at Marseilles. M. Pons was the first that discovered the other two. The Revue has already noticed that comet whose revolution was deter mined by M. Euke, and which has been designated as the comet of a short period; it will hereafter, no doubt, receive an appropriate name, like the other bodies of our system.

M. Gambey presented to the Academy two instruments, constructed on new principles, 1. A compass of declination; and 2, an heliostat, With respect to the invention and execution of astronomical instruments, M. G. is, at present, the first artist in Europe.

M. the Abbé Halma, translator of the Almagest, is now publishing a French translation of Ptolemy's “Manual Tables," hereby rendering a new service to astronomy. He is also prosecuting "Enquiries on the Zodiack of Deuderah," and professes to prove that it does not reach higher than the year 364 of the Christian æra.

M. Coquebert Montbret, reporter of the "Commission of Statistics," after

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announcing the prizes decreed, notices the "Statistic Researches" of M. de Chabrol, relative to the city of Paris, and the department of the Seine. The rest of this work will shortly appear.

Mention is next made of works relating to the colonies. M. de Jonnès has commenced the publication of some useful memoirs on the "Antilles;" they are intended to complete the "Natural History of Guadaloupe and Martinico." Certain other works have been collecting documents on the same islands; were this plan extended to French Guiana, and our establishments in the Indian ocean, our colonies would be better known than many parts of the interior of France.

M. B. de Chateauneuf produced a "Memoir on the Mortality of Women, arrived at Ages from Forty to Fifty." In this he proves by evidence, that appears undeniable, contrary to a received opinion, that the mortality of men is greater at this period than that of women. This consequence has been drawn from observations made in places extremely remote, and in very different climates; in the south of France, in the north of Russia, and in the intermediate countries.

A memoir of M. de Jonnès, on the extent of lands susceptible of cultivation in the French colonies, makes it plainly appear, that even one-third of the lands as yet not cleared, put into a state of cultivation, would furnish sup plies, not only for the consumption and manufactures of France, but for exportation.

Messrs. P. Duchatelet and P. de Contreille, medical doctors of the faculty of Paris, have published some Remarks on the River Bièvre. About the year 1790, the improvement of the course of its waters, so as to render its banks more salubrious, had formed the subject of an interesting publication by M. Hallé. A considerable part of the population of the Faubourg St. Marccau are daily employed on its banks, or in the vicinity, the importance of whose establishments would be greatly augmented, if the banks were lined with a wall of masonry, if a pavement were laid down on the soil, if toll-gates were removed, &c.

In chemistry, facts are, progressively, accumulating, so as, in time, to form a general theory that may include them, in all their relations, and reveal, as far as it is possible, the causes and laws of their action. In such a state of the sci

once, there is reason to fear that facts will be inaccurately observed, and inperfectly described. It has been bitherto believed, that the combination of chlore with percarbonated hydrogen, contained equal portions of these two substances. M. Despretz has shown that the volume of chlore is only half of that of the percarbonated hydrogen.

M. Dulong, recently admitted into the academy as a member, has made some new discoveries on respiration, and os the causes of animal heat. He has found that the volume of carbonic acid, formed in the act of respiration, was always less than that of the absorbed oxygen; experiments show it to be by one third, in birds and carnivorous quadrupeds, and by one tenth in the herbivorous. He has, moreover, remarked, that there was constantly so strong an exhalation of azote, that, in herbivorous animals, the volume of air expired surpassed that of the air inspired, notwithstanding the diminution of volume of the carbonic acid gas. And, lastly, he has found the portion of heat, corresponding to that of the acid, to be scarcely half of the total heat yielded by the animal, unless it be carnivorous; and that, in herbivorous kinds, it does not reach three quarters of the same quantity. From these premises, M. Dulong concludes that there remains some other cause, different from the fixation of oxygen, to account for animal heat in its totality.

The loss sustained by the academy, in the death of M. Haüy, gave reason to apprehend that the public would be deprived of a complete edition of his works, which the professor was preparing. Five volumes had already appeared, and the impression of the sixth and last is now proceeding, under the inspection of M. Delafosse, pupil of M. Haüy, and selected, by him, to cooperate in his labours.

M. Constant Prevost, a skilful naturalist, a pupil of M. Brongniart, has traced the geological traits of Normandy and Picardy, from Calais to Cherbourg. At the two extremities of this line, nearly eighty leagues in extent, we find rocks of a similar character; these rocks appertain to the primitive soil; and, in some measure, form the borders of the immense basin, in which are deposited the rows or shells of the posterior earths. The middle of this basin is pretty near Dieppe; there we perceive, only, such as are the most su perficial, and they are almost all hori

zontal.

zontal. The intermediate shelves rise up, obliquely, on each side. M. Prevost has represented this sort of a natural cup, in a drawing, which is rendered still more intelligible by an ingenious colouring. The grand divisions of the land are distinguished, in their general character, and with their subdivisions, and so all the facts that compose the geological history of the country are included. A description is subjoined of the fossils, as well as of the couches or strata that contain them. Among others, is a species of reptile, named ichthyosaurus, partaking of the nature of a lizard and a fish, and the most ancient, perhaps, that we are acquainted with. There are, also, fishes, with some unknown species of crocodiles and cerites, a species of shell-fish that abound in the rocks, and are found scattered in heaps, one among another, but separated by very thick strata of chalk, on which none of them are found.

M. Dutrochet has made additional experiments on the direction which the different parts of plants take, from ger mination to their complete develop ment. He has found, that when grains are turned, and their axis of rotation is inclined to the horizon, though but slightly, the two seminal caudexes take the same direction, and the radicle follows that inclination. If the axis be perfectly horizontal, the two caudexes take a direction in a tangent to the very small circle described by the embryo. In stalks that have leaves, when submitted to the rotation, the leaves turn their superior faces towards the centre of rotation, and the petiole, or supporting stalk, bends conformably to that disposition.

M. Dupetit Thouars considers the flower as a transmutation of the leaf, and of the bud that depends on it. His experiments on the juice of vegetables, present facts which seem no further connected with that substance than as it is an assemblage of vegetable fibres, such as would be no less observed in other assemblages that have not the properties of the juice. It is generally supposed that a tree, deprived of its bark, loses its power of vegetation. M. D. T. has peeled trees, for three years together, and they have sustained no injury. He thinks the elm endures this mutilation the best, but the oak decays under it. A young peeled elm produced, at first, some protuberances that took a greenish tint, and were soon

found to be buds. These disappeared, in winter; but, in the spring, there appeared a number, large enough to recom

mence a new tree.

M. Raffeneau Delille, professor of botany at Montpellier, and a correspondent of the academy, has described a singular plant, of the family of corbels, or gourds. On the same stalks it bears hermaphrodite and male flowers. Its fruit, nearly two feet in length, and of a proportionate thickness, is covered with a resinous and inflammatory powder, plentiful enough to be gathered by scraping off. The author judges it to be analogous to the vegetable wax of the myrica cerifera of North America, and to the same of the ceroxylum andicola, discovered in the Cordilleras by Messrs. de Humboldt and Bonpland. M. Jacquin, from whom M. Delille received the grains of this plant, has named it beninaga cerifera.

M. de Humboldt is publishing the tenth number of his superb Collection of Mimosa, and, in conjunction with M. Kanth, the twenty-second number of the new Genera and Species of the Torrid Zone. M. Kanth has published the first volume of a Treatise, wherein be examines, afresh, the Characters of the Genera of the Family of Mallows, also those of the Ciliaceous and Butnera

kind.

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M. Dupetit Thouars has presented the commencement of an History of the Plants of the Family of Orchis. This forms part of a Flora of the Isles of France and Bourbon, which M. D. T. has been long employed upon.

Several physiologists attribute the faculty of absorbing exclusively to the lymphatic vessels; some others, however, allow it also to the veins, for all that is not chyle. This question has been, of late, the subject of renewed discussion. M. Segelas has communicated to the academy, and repeated, before its committee, some experiments, which not only confirm, in general, the absorbent faculty of the veins, but prove, also, that certain substances are only absorbed by those vessels, or, at

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