ART. I. Leçons de Géologie, &c.; i. e. Lectures on Geology, delivered in the College of France, by J. C. DELAMÉTHERIE. 3 Vols. 8vo. About 400 Pages in each. Paris. 1816. Imported by De Boffe. Price 11. Ios. sewed.

Two

'wo of the prevalent fashions of the present generation are exhibited in singular combination in these volumes; viz. book-making and world-making; and a waste of paper is ostentatiously displayed in numberless repetitions of the same idea, in paragraphs consisting of two or three lines or aliquot parts of a line, and in hunting a general position through the tedious maze of all its particular illustrations. Many passages are almost entirely copied from prior works or memoirs of the same author, or from those of contributors to his Journal de Physique and other scientific publications: the principles and raw materials of the universe are copiously set forth in an ample introduction; and the component parts of the surface of our planet flit before us, in various array, according to the tenor of the page or the sub-division of the section. This series of lectures, moreover, participates in several of the defects to which we had occasion to advert in our strictures on its counterpart, the Lectures on Mineralogy, by the same learned and ingenious Professor: but it is not, like the former, a mere assemblage of continuous chains of definitions and explanations of terms; nor will the third volume, which is APP. REV. Vol. LXXXIV.

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chiefly occupied by a view of the different theories of the earth that have been proposed by antient and modern writers, be deemed either tedious or uninstructive. Had the doctrinal portions of the other two volumes been condensed into one, and their logical connection been less frequently interrupted or obscured by masses of supposable inductions, the work might have afforded a more desirable treat to readers of cultivated taste and judgment.

That geology is an important and interesting study, we pretend not to deny: but, when M. DELAMÉTHERIE talks of communicating satisfactory notions on the subject to his pupils, and conceives this branch of knowlege to be nearly as much matured as the other departments of physical science, he unconsciously exalts his own conjectures, and those of others, to the rank of demonstrable and established truths. Assuming as facts that the terrestrial globe once existed in a fluid state, and that it subsequently acquired its present condition, he has reduced into a systematic form all the results of his former writings and present meditations, which bear on this portion of his professional labours; combined with the suggestions, reasonings, and illustrations of other eminent geologists. Without, therefore, very closely tracking his footsteps through all the multiplied but similar windings of a huge labyrinth, we shall best consult the patience of our readers, and the right apprehension of the author's own leading sentiments, by disentangling the intricacy of his path, and taking no account of those superfluous accumulations which darken rather than illuminate his progress.

To facilitate our conceptions of the formation of our own planet, M. DELAMÉTHERIE most liberally invites us to take cognizance of the formation of all bodies that exist. Know, then, grateful reader, that they are all composed of primary matter; and that each particle of that matter is one and indivisible, and endued with an inherent force which may be brought into visible exertion, as in the case of chemical decomposition. Now, this force he regards as the cause of all the different movements of bodies, impulse, attraction, repulsion, galvanic action, &c. We conceivé, however, that these are not motions, but the real or supposed causes of motions. Besides, in the very outset of his introduction, the author leads us to infer that the cause of attraction lies beyond the sphere of our knowlege; and, if so, we are not warranted to assert that it is the same with the inherent force of the particles of primary matter. A body impelled by this inherent force, and impinging on another, gives impulse to the latter without losing its own intrinsic energy, as in the unbending of a spring: but

the communicated impulse may be lost, and most commonly is; whence we should carefully distinguish between inherent and communicated force, though we are ignorant of the nature of both. We have not ascertained, moreover, the nature of primary matter, although the author very slily suspects that it may be the akasch; a term of singular harmony and significance; and which, for the accommodation of country-gentlemen, he most kindly interprets by nebulous matter, tohu bohu, chaos, and rudis indigestaque moles.

'But,' he adds, whatever this primary matter may be, it has been arranged and co-ordained by its inherent force, according to the laws of affinities. It has formed, by a general crystallization, all existing bodies. *

'The great globes, or stars, first received their form; and next, on these globes, other less considerable bodies: as, for example, on our own globe, minerals, vegetables, and animals. Analogy suggests that, on the other globes, have in like manner been formed bodies more or less analogous to those last mentioned. 'The great globes appear to be of two kinds: some are luminous, as the suns.

Others are opake, like the planets.

All these bodies have been formed by crystallization. ...

Without entering into all the details of crystallography, which I have explained in my Lectures on Mineralogy, (tom. i.) it may suffice to recollect that the phænomena of crystallization are owing to two principal causes :

1. The figure of the primary parts of matter:

2. The force of affinity.'

Such is the basis of the author's theory of the formation of the universe, or rather of the arrangement and concretion of the chaotic matter, according to the laws of crystallization; and all the chemical, galvanic, magnetical, and electrical movements, which render his introduction such a stirring scene, are little more than pretended illustrations of his general principles. These principles, however, it would be idle labour either to defend or impugn, till we know more than we do at present of the primary parts of matter, and of its primitive, elementary, and integrant particles, each of which expressions has a distinct meaning: but our readers may be amused, if not instructed, by the ease and grace with which the author fashions suns, planets, and comets, with his plastic nebulous matter and powerful streams of Voltaic agency.

<* See my Principles of Natural Philosophy, published in 1778; my Memoir on the general Crystallization of Matter, Journal de Physique, tom. xvii. p, 258.; my Theory of the Earth, tom. iii.; and my Views of the Galvanic Action, Journal de Physique, tom. lxxvi. and lxxvii.'

The earth was, we may presume from analogy, formed in the same manner as the other planets; namely, by the crystallization of the primary matter of which the different mineral substances are composed. Some of these substances are crystallized in a regular and others in a confused manner; and the result of all these partial crystallizations was the production of the terrestrial globe. As this summary of his theory is, however, too general and vague for the purposes of the geologist, the author proceeds to unfold the facts, or induc tions, on which he conceives it to be grounded. From a recapitulation of the statements of scientific observers of the figure, mean density, and mean temperature of the earth, he infers its originally fluid state, and the gradual reduction of its temperature in the lapse of ages. Various fluids, as those of light, heat, electricity, the zodiacal light, the polar aurora, magnetism, &c. are supposed to have exerted their respective actions on the composition and arrangement of our planet. Under the article magnetism, in particular, are inserted many valuable observations on the declination, inclination, and variation of the needle; while the consideration of the gaseous substances which envelope the globe suggests a particular review of the composition and height of the atmosphere, and its currents, or winds.

An entire section is occupied with a sketch of the earth's surface; namely, of its great continents, mountains, islands, &c.; the distribution of its primary, secondary, and volcanic rocks, its alluvial soil, its fissures, and caverns; and the extent of its seas, principal lakes, and rivers. The author observes that, 'after having succinctly stated the principal facts which the surface of the globe presents to our contemplation, and those which we have been enabled to deduce from theory, we proceed to investigate the manner in which, according to the actual state of knowlege, we may suppose it to have been formed. Let us first consider the simple substances, or elements, of which it is composed.' Having enumerated fiftyfour of these elementary substances, and accompanied the list with some pertinent remarks, he thus continues: *

We cannot conceive the primary combinations of matter, unless every one of its parts had an inherent motion, which induced them to tend to their mutual union and aggregation. These aggregates have formed the 54 substances which we have just mentioned. Every one of these 54 substances had equally an inherent force, by which its union and its combination, according to circumstances,

* As we have given a specimen of the author's short paragraphs, &c. we shall henceforth take leave occasionally to consolidate them.

were

were effected. These substances were formed successively in particles extremely attenuated, each of which contained only a portion of the new compound; and these particles, in the nascent state, as we may express it, quickly combined, either with themselves, and formed masses of the same compound, or with others, and formed new compounds. All these new compounds probably formed concrete and not liquid bodies.'

In his long developement of these positions, the phrase nascent state, which recurs in almost every second or third Hine, certainly performs wonders; and it is vain to question the efficacy of such a talisman; for who knows what a particle of primary matter, in its nascent state, may not perform? In this nebulous atmosphere with which our tribunal is surrounded, we confess that we cannot even discern the meaning of the expression. Not so M. DELAMÉTHERIE. Keeping fast hold of his divining rod, he travels, in the full assurance of faith, over all the known compounds of the earth, and solves the mystery of their union by the appetencies of primary particles, à l'état naissant, or, in principio rerum, whether they may be supposed to have originally existed in a state of igneous, aqueous, or aëriform fluidity.

From the water of crystallization of the globe, he next deduces the ocean, at first more extensive than at present, and subjected to movements analogous to those of our actual seas, though the tides and currents must have been far more powerful. The phænomena and effects of these movements may reasonably be conjectured to have been different before and after the appearance of the continents above the waters; and the consideration of these various states naturally leads to an extended retrospect of the author's memoir on the action of currents, formerly published in the 67th volume of the Journal de Physique, as well as of the substance of the most valuable observations which have been instituted relative to the same subject by natural philosophers and navigators. Other streams are traced to the disruption of lakes which appear to have filled immense valleys, and to have forced open a passage for themselves, producing manifest changes on the surface over which they have flowed. The estimates of the water that falls on the earth's surface in different latitudes, the quantity that is evaporated, the amount of what is discharged into the sea by rivers, and the origin of springs and mineral and thermal waters, are next briefly discussed; without, however, communicating any new information, or greatly advancing our progress in the history of the earth's structure. We pass, therefore, to the fifth section, which treats of the composition of the primitive regions of the crust of the earth, and of their mountains,

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