Finally, the researches of modern geologists have given abundant confirmation to the sacred history, not only with respect to the general deluge, but also with regard to the age of the earth." Early in the century, and, indeed, until within a few years, several geological phenomena were considered, by superficial inquirers, as indicating that the creation of the globe we inhabit was an event much more remote than the sacred history represents it; and some theorists even went so far as to profess a belief that it existed from eternity. These opinions were kept in countenance only as long as geology was in its infancy. Every succes

took refuge in another system, in which he recognizes the deluge, and only contends for placing it as far back as three thousand five hundred years before Christ.

y Sir WILLIAM HAMILTON and Mr. FERBER particularly applied themselves to the study of volcanoes, without giving general systems. They affirmed that the indications furnished by subterraneous and volcanic phenomena, and particularly by the beds of lava, announce the antiquity of the earth to be far greater than the sacred history represents it. But they did not advert to the fact, that all lavas are not composed of the same substance. All have not undergone the same degree of vitrification, and of course are more or less susceptible of decomposition. And even when their composition is the same, much depends on the state in which they are emitted. When poured from the crater in the fermentation of boiling liquefaction, a scoria or dross rises, like broken waves on the surface, and is easily pulverized by the air and weather. When the heat is less violent, or when the torrent is cooled in its course, an even and almost impenetrable surface defies the influence of the atmosphere. These philosophers do not recollect that Herculaneum, the date of whose destruction is well known, is covered by nearly seventy feet of lava, interspersed with seven distinct seams of friable earth; and the whole covered with good soil; yet all this has been the undoubted production of less than eighteen bundred years. HOWARD'S Thoughts on the Globe.

In like manner, Count BORCH, in his Letters on Sicily and Malta, professes to believe that Etna is at least eight thousand years old, which he infers from the beds of vegetable earth which he discovered between different beds of lava. Yet M. DOLOMIEU, who has greatly distinguished himself by the acuteness and success of his geological inquiries, expressly tells us that such earth does not exist between the beds of lava of which the Count speaks, and thus destroys the foundation of his whole argument. But even if vegetable earth were found in the circumstances supposed, no conclusion relative to its age could fairly be deduced from this fact, as some lavas become fertile much sooner than others. The Chevalier GIOANNI, in 1787, found lavas, projected in 1766, in a state of vegetation, while other lavas, known to be much more ancient, still remained barren. KIRWAN' Geological Essays, p. 104, 105,

sive step which has been lately taken in the improvement of this science has served to show their fallacy. The investigations of the latest and most accurate philosophers have afforded proof little short of demonstration, that the earth, at least in its present form, cannot have existed longer than appears from the Mosaic account; the absolute falshood of many positive assertions, and specious inferences, hostile to the scripture chronology, has been evinced; and thence has arisen a new presumptive argument in support of the authenticity of that Volume, which contains the most ancient, and the most precious of all records.

METEOROLOGY,

The natural history of the atmosphere began to be cultivated, as a science, in the seventeenth century. The ancients, for want of the necessary instruments, were almost wholly unacquainted with

it. But soon after the invention of the thermometer and the barometer, the learned men of Europe began to avail themselves of the manifest advantages which these instruments gave them, in studying the origin, nature, and effects of those changes which take place in the atmosphere, especially with respect to heat and cold, motion and rest, moisture and gravity: still, however, from the small number of the meteorological observations made by accurate philosophers; from the want of an extensive comparison of the results of different observations; and especially from the low state of those sciences most intimately connected with meteorology, little progress had been made in this department of knowledge prior to the commencement of the century under review. And though it must be acknowledged that this subject is one of those which are still far from

being satisfactorily developed, yet so much has been done, during the period under consideration, to throw light upon it, and so many observations and discoveries have been made, either directly or remotely relating to it, that it has, within a few years, assumed an aspect more interesting, practical, and approaching to the form of a system, than ever before.

At the commencement of the eighteenth century, the ascent of water in the atmosphere, in the form of vapour, had been but little investigated, and was very imperfectly understood. NIEUENTYT and others had taught that the particles of fire, by adhering to those of water, made up molecule, or small bodies specifically lighter than air. Dr. HALLEY supposed that by the action of heat, the particles of water are formed into hollow spherules, filled with a finer air, highly rarified, of less specific gravity than the atmosphere, and, of course, disposed to rise in it. While Dr. DESAGULIERS thought that the ascent of aqueous particles was owing to their being converted into an elastic steam. Such was the state of opinions with regard to this fact, when Dr. HAMILTON, of Great-Britain, undertook the investigation of the subject, and proposed a new theory, He held that evaporation is the gradual solution of water in air, and that the former is suspended in the latter in the same manner as salts, or other soluble substances are suspended in aqueous fluids. The same doctrine had been, in substance, suggested before by ⚫ several philosophers, particularly by M. LE ROY, in 1751; by Dr. FRANKLIN, in 1756; and by MUSCHENBROECK, in 1769. But though these and

Essay on the Ascent of Vapours, &c. This Essay was first read before the Royal Society in 1765, and was afterwards published, with others, under the title of Philosophical Essays, by HUGH HAMILTON, D. D. F. R. S a Bishop WATSON's Chemical Essays, vol. i. p. 317.

some others, had spoken of the solubility of water in air, before Dr. HAMILTON, yet he was the first who treated the subject with precision, or who applied it systematically to the explanation of meteorological phenomena. This opinion was afterwards, in substance, adopted by Dr. HUTTON, and exhibited in his ingenious Theory of Rain, and continued for a number of years to be the popular doctrine.

In 1786, M. DE LUC, of Geneva, published a new theory on this subject, which has been since generally considered as superseding the doctrine of HAMILTON and HUTTON. Observing that evaporation takes place in vacuo, as well as in the open air, M. DE LUC rejected the opinion that vapour is the solution of water in air, and taught that this effect is produced by the chemical combination, or union of the particles of heat with those of water. Hence he accounted for the great. loss of sensible heat, in every process of evaporation, according to the celebrated doctrine of latent heat taught by Professor BLACK. He made a number of curious observations and experiments on this subject, by which he ascertained that water, after this ascent in the atmosphere, does not exist in a sensibly humid form; whence he concluded that it passes into a form entirely different from itself, and probably becomes air. This doctrine is evidently founded on the mutual convertibility of water into air, and the reverse, discovered by CAVENDISH and some later chemists. The same theory, of the solution of water in heat, was also embraced by M. LAVOISIER, and appears to be now the most fashionable mode of interpreting the phenomenon in question.

b Transactions of the Royal Society of Edinburgh, vol. i.

See Recherches sur les Modifications de l'Atmosphere, par J. A. De Luc. 8vo. 2 vols. Geneva. 1772. And also Idees sur la Meteorologie, a more full and satisfactory work, by the same author. 1786.

Besides forming and giving to the world this ingenious theory of evaporation, M. DE LUC has also rendered essential service to the science of meteorology, by his patient and persevering observations on the comparative degrees of moisture in the atmosphere, in different situations. On this subject he has brought to light a number of facts equally new and interesting. His countryman, M. DE SAUSSURE, has also laboured very successfully in the same field of inquiry; and though not always with an entire coincidence of opinion and result, yet with sufficient agreement on most important points. There are probably no two individuals to whom the scientific world is more indebted for the minuteness, the accuracy, and the success of their meteorological investigations, than to these philosophers of Geneva.

About the year 1755 Mr. EELES first suggested the probable influence of Electricity in the process of evaporation. He taught that there was but one way of altering the specific gravity of the particles of water, so as to render them lighter than air, and, consequently, buoyant in that fluid, viz. the adding to each particle a sufficient quantity of some fluid which possesses much greater elasticity and rarity than air. Such a fluid is Electricity; which, therefore, he supposed to have a very important agency in the ascent of vapours. The influence of the electric fluid in producing changes in the atmosphere has been since further investigated, and the principles on which it operates more satisfactorily developed, by FRANKLIN, DE SAUSSURE, BERTHOLON, and other modern inquirers.

Closely connected with the doctrines which have been taught on the subject of evaporation are the several theories of Rain to which modern

d Essai sur l'Hygrometrie, 4to. 1783,