built upon assumption alone. It lays down principles which it cannot support, and in stating observations to other theories, it rather clears the way for the advance of something unborn than establishes its own positions.

In reply to this argument, which, we admit, is very ingeniously conducted, it is forcibly asked, by the author of the Comparative View of the two systems, in direct reply to Mr. Playfair's Illustrations of the Huttonian Theory, "To what purpose are the various sources of heat enumerated in this reasoning? To prove that it may exist, or be produced independent of burning. This will be readily granted; but the reasoning can prove nothing farther. It can be satisfactorily shewn that any of the known causes of heat are as incapable of producing it in the interior parts of the globe, to that extent which must be supposed in the Huttonian theory, as combustion, which, even by its defenders, is confessed to be inadequate to that purpose."

In regard to the third general position, that the strata, after having been fused and consolidated by subterranean heat, are elevated by the same power, the same general objection is applicable, which has been already urged against the preceding principle, viz. the difficulty or impossibility of obtaining and preserving a degree of heat sufficient for such a purpose. And even were this granted, no principle is pointed out in the theory, by which the action of such a power can be regulated; why it may not anticipate or be too late for its due season of action, and be as often the cause of havoc and disorder, as it is asserted to be the regular and pre-ordained instrument of the renovation of a continent. Hence, the principle assumed is at once gratuitous and improbable.

In a work restricted, as is the Pantologia, to narrow extent in the discussion of the different articles of which it is composed, it is always a point of very considerable consequence to detect insuperable objections to a system in limine: for it enables the editors to appropriate many of their pages, which would otherwise be devoted to the same subject, to inquiries of more importance, be cause vested on a firmer foundation. If the objections to the Plutonic theory, as already urged, few as they are, be conceived decisive (and we can scarcely imagine any other verdict from our readers), we may well be saved the trouble of pointing out those inconsistencies it labours under, as well in regard to the actual position of many of the stony rocks of the globe contemplated in mass, as in the appearances and properties of individual fossils: though we feel persuaded that the arguments resulting from a minute investigation into both these points, would be altogether as complete as in the question of principle. It is sufficient, however, to observe, that notwithstanding its magnificence of structure, and extent of application, notwithstanding the speciousness of its first introduction, and the talents with which it has been supported, the Plutonic theory is

Neptunian theory-Under this view of the origin and structure of the globe, less superb indeed, but possessing a much wider appeal to facts than the preceding, it is conceived that aqueous solution has been the agent by which the phænomena on the superficies of the globe have been produced. It is conceived that the materials of which our strata consist were at one time dissolved or sus

successively consolidated iu various combinations, partly by crystallization, and partly by mechanical decomposition. Granite being the rock which composes the most elevated part of the globe, and which likewise forms the basis on which the greater, number of the strata rest, is supposed to have been first formed, the different parts of which it consists, felspar, quartz and mica, having concreted by a crystallization nearly simultaneous. This is conceived to have been accompanied with, and followed by, a similar consolidation of the other primitive strata, gneis, micareous schist, argillaceous schist, porphyry, quartz, &c.

Those rocks compose the chief elevations of the globe. They are never found to contain any organic remains, and of course their formation must have been prior to the existence of the vegetable and animal kingdoms.

to us.

From the period of the formation of these strata, it is contended that the water covering the surface began to diminish in height by retiring gradually into cavities in the internal parts of the earth. And if we may be permitted to recur, by an effort of the imagination, to that epocha in which, according to sacred and profane historians, the water and earth were confounded, and the confused mixture of all principles formed a chaos, we shall see that the laws of gravity inherent in matter must have carried it down,and necessarily produced the arrangement which observation at present exhibits The water, as the least heavy, must have purified itself, and arisen to the surface by a filtration through the other materials: while the earthy principles must have precipitated, and formed a mud, in which all the elements of stones were confounded. In this very natural order of things, the general law of affinities, which continually tends to bring together all analogous parts, must have exerted itself with its whole activity upon the principles of this almost fluid paste, and the result have been a number of bodies of a more definite kind, in crystals more or less regular; and from this muddy substance, in which the principles of the stones were confounded that compose the granite, a rock must have been produced, containing the elementary stones all in possession of their distinct forms and characters. In this manner it is that we observe salts of very different kinds develop themselves in waters which hold them in solution; and in this manner it still happens that crystals of spar and gypsum are formed in clays which contain their component parts.

It may easily be conceived that the laws of gravitation must have influenced the arrangement and disposition of the products. The most gross and heavy bodies must have fallen, and the lightest and most attenuated substances must have arranged themselves on the surface of the foregoing; and this it is which constitutes the primitive schi ts, the gneis, the rocks of mica, &c, which commonly

repose upon masses of coarse-grained granite. The disposition of the fine-grained granite in strata, or beds, appears to depend on this position, and the fineness or tenuity of its parts. Being placed in immediate contact with water, this Quid must naturally have influenced the arrangement which it presents to us; and the elements of this rock, being subjected to the effect of waves, and the action of currents, must have formed strata.

The rocks of granite being once established as the nucleus of the superficies of our globe, we may, from the analysis of its constituent principles, and by attending to the action of the various agents capable of altering it, follow the changes to which it has been subjected, step by step.

Water is the principal agent whose effects we shall examine. This fluid, collected in the cavity of the ocean, is carried by the attmosphere to the tops of the most elevated mountains, where it is precipitated in rain, and forms torrents, which return with various degrees of rapidity into the common reservoir. The uninterrupted motion and fall must gradually attenuate and wear away the hardest rocks, and carry their detached parts to distances more or less considerable. The action of the air, and the varying temperature of the atmosphere, facilitate the attenuation and the destruction of these rocks. Heat acts upon their surface, and renders it more accessible and more penetrable to the water which succeeds; cold divides them, by freezing the water which has entered into their texture; the air itself affords the acid principle, which attacks the limestone, and causes it to effloresce; the oxygen unites to the iron, and calcines it: insomuch that the concurrence of causes favours the disunion of principles; and consequently the action of water, which clears the surface, carries away the products of decomposition, and makes preparation for a succeeding process of the same nature.

The first effect of the rain is therefore to depress the mountains. But the stones which compose them must resist in proportion to their hardness; and we ought not to be surprised when we observe peaks which have braved the destructive action of time, and still remain to attest the primitive level of the mountains which have disappeared. The primitive rocks, alike inaccessible to the injury of ages as to the animated beings which cover less elevated mountains with their remains, may be considered as the source or origin of rivers and streams. The water which falls on their summits flows down in torrents by their lateral surfaces. In its course it wears away the soil upon which it incessantly acts. It hollows out a bed, of a depth proportioned to the rapidity of its course, the quantity of its waters, and the hardness of the rock over which it flows; at the same time that it carries along with it portions and fragments of such stones as it loosens in its course.

These stones, roiled along by the water, must strike together, and break off their projecting angles: a process that must quickly have afforded those rounded flints which form the beds of rivers. These pebbles are found to diminish in size, in proportion to the distance from the mountain which affords them; and it is to this cause that Mr. Dorthes has referred the disproportionate magnitude of the pebbles which form our ancient worn stones, when compared with those of modern date; for the sea extending itself formerly much more inlaud, in the direction of the Rhone, the stones which it received from the rivers, and

threw back again upon the shores, had not run through so long a space in their beds as those which they at present pass over. Thus it is that the remains of the Alps, carried along by the Rhone, have successively covered the vast interval comprised betweent he mountains of Dauphiny and Vivarais, and are carried into seas, which deposit them in small pebbles on the shore.

The pulverulent remains of mountains, or the powder which results from the rounding of these flints, are carried along with greater facility than the flints themselves: they float for a long time in the water, whose transparency they impair; and when these same waters are less agitated, and their course becomes slackened, they are deposited in a fine and light paste, forming beds more. or less thick, and of the same nature as that of the rocks to which they owe their origin. These strata gradually become drier by the agglutination of their principles; they become consistent, acquire hardness, and form siliceous clays, silex, petrosilex, and all the numerous class of pebbles which are found dispersed in strata, or in banks, in the ancient beds of rivers. The mud is much more frequently deposited in the interstices left between the rounded flints themselves, which intervals it fills, and there forms a true cement that becomes hard, and constitutes the compound stones known by the name of pudding-stones and grit-stones; for these two kinds of stones do not appear to differ but in the coarseness of the grain which forms them, and the cement which connects them together.

We sometimes observe the granite spontaneously decomposed. The texture of the stones which form it has been destroyed; the principles or component parts are disunited and separated, and they are gradually carried away by the waters. Water filtrating through mountains of. primitive rock, frequently carries along with it very minutely-divided particles of quartz; and proceeds to form, by deposition, stalactites, agates, rock crystal, &c. These quartzoes stalactites, differently coloured, are of a formation considerably analogous to that of calcareous alabasters; and we perceive no other difference between them than that of their constituent parts. Thus far we have exhibited, in a few words, the principal changes, and various modifications, to which the primitive rocks have been subjected. We have not yet observed either germination or life; and the metals, sulphur, and bitumens, have not hitherto presented themselves to our observation. Their formation appears to be posterior to the existence of this primitive globe; and the alterations and decompositions which now remain to be inquired into, appear to be produced by the class of living, or organized beings.

On the one hand, we behold the numerous class of shell animals, which cause the stony mass of our globe to increase by their remains. The spoils of these creatures, long agitated and driven about by the waves, and more or less altered by collision, form those strata and banks of lime-stone, in which we very often perceive impressions of those shells to which they owe their origin. On the other hand, we observe a numerous quantity of vegetables that grow and perish in the sea; and these plants, likewise deposited and heaped together by the currents, form strata, which are decomposed, lose their organization, and leave all the principles of the vegetable confounded with the earthy principle. It is to this source

that the origin of pit-coal, and secondary schistus, is usually attributed; and this theory is established on the existence of the texture of decomposed vegetables very usually seen in schisti and coal, and likewise on the presence of shells and fish in most of these products. It appears that the formation of pyrites ought in part to be at tributed to the decomposition of vegetables: it exists in greater or less abundance in all schisti and coal. A wooden shovel has been found buried in the depositions of the river De Ceze, converted into jet and pyrites. The decomposition of animal substances may be added to this cause; and it appears to be a confirmation of these ideas, that we find many shells passing to the state of pyrites.

Not only the marine vegetables form considerable strata by their decomposition; but the remains of those which grow on the surface of the globe ought to be regarded among the causes or agents which concur in producing changes upon that surface. We shall separately consider how much is owing to each of these causes; and shall follow the effects of each, as if that cause alone was employed in modifying and altering our plane. 1. The secondary calcareous mountains are constantly placed upon the surface of the primitive mountains; and though a few solitary observations present a contrary order, we ought to consider this inversion and derangement as produced by shocks which have changed the primitive disposition. It must be observed also, that the disorder is sometimes merely apparent; and that some naturalists of little information have described calcareous mountains as inclining beneath the granite, because this last pierces through the envelope, rises to a greater height, and leaves at its feet, almost beneath it, the calcareous remains deposited at it's base.

Sometimes even the lime-stone fills to a very great depth the crevices or clefts formed in the granite, sometimes schistus, or trap, occasionally containing petrifactions. These, in the Wernerian system, are called intermediate or transition rocks or strata. It likewise happens frequently enough that such waters as are loaded with the remains of the primitive granite heap them together, and form secondary granites which may exist above the calcareous stone. These calcareous mountains are decomposed by the combined action of air and water; and the product of their decomposition sometimes forms chalk or marle. The lightness of this earth renders it easy to be transported by water; and this fluid, which does not possess the property of holding it in solution, soon deposits it in the form of gurhs, alabasters, stalactites, &c. Spars owe their formation to no other cause. Their crystallization is posterior to the origin of calcareous mountains.

Waters wear down and carry away calcareous mountains with greater ease than the primitive mountains: their remains being very light, are rolled along, and more or less worn. The frag ments of these rocks are sometimes connected by a gluten or cement of the same nature; from which process calcareous grit and breccias arise. These calcareous remains formerly deposited themselves upon the quartzose sand; and the union of primitive matter. and secondary products, gives rise to a rock of a mixed nature.

2. The mountains of secondary schistus frequently exhibit to us a pure mixture of carthy principles, without the smallest vestige of bituThese rocks afford, by analysis, silex, alumina, magnesia, lime in the state of caobonate,

men.

and iron; principles which are more or less united, and consequently accessible in various degrees to the action of such agents as destroy the rocks hitherto treated of.

The same principles, when disunited, and carried away by waters, give rise to a great part of the stones which are comprised in the magnesian class. The same elements, worn down by the waters, and deposited under circumstances proper to facilitate crystallization, form the schorls, tourmaline, garnets, &c. We do not pretend by this to exclude and absolutely reject the system of such naturalists as attribute the formation of magnesian stones to the decomposition of the primitive rocks. But we think that this formation cannot be objected to for several of them, more especially such as contain magnesia in the greatest abundance.

It frequently happens that the secondary schists are interspersed with pyrites; and, in this case, the simple contact of air and water facilitates their decomposition. Sulphuric acid is thus formed, which combines with the various constituent principles of the stone; whence result the sulphates of iron, of magnesia, of alumina, and of lime, which effloresce at the surface, and remain confounded together, Schists of this nature are wrought in most places where alum works have been established: and the most laborious part of this undertaking consists in separating the sulphats of iron, of lime, and of inagnesia from each other, which are mixed together. Sometimes the magnesia is so abundant that its sulphat predominates. The sulphat of lime, being very sparingly soluble in water, is carried away by that liquid, and deposited to form gypsium; while the other more soluble salts, remaining suspended, form vitrolic mineral waters. The pyritous schists are frequently impreg nated with bitumen, and the proportions constitute the various quantities of pit-coal.

It appears that we may lay it down as an incontestable principle, that pyrite is abundant in proportion as the bituminous principle is more scarce. Hence it arises, that coals of a bad quality are the most sulphureous, and destroy metallic vessels, by converting them into pyrite. The foci of volcanos appear to be formed by a schist of this nature; and in the analyses of the stony matters which are ejected, we find the same principles as those which constitute this schist. We ought not therefore to be much surprised at finding schorls among volcanic products; and still less at observing that subterranean fibres throw sulphuric salts, sulphur, and other analogous products, out of the entrails of the earth."

3. The remains of terrestrial vegetables exhibit a mixture of primitive earths more or less coloured by iron: we may therefore consider these as a matrix in which the seeds of all stony combinations are dispersed. The earthy principles assort themselves according to the laws of their affinities; and form crystals of spar, of plaister, and even the rock crystals, according to ali appearance: for we find ochreous earths in which these crystals are abundantly dispersed ; we see them formed almost under our eyes. We have frequently observed indurated ochres full of these crystals terminating in two pyramids.

The ochreous earths appear to deserve the greatest attention of naturalists. They constitute one of the most fertile means of action which nature employs; and it is even in earths nearly similar to these that she elaborates the diamond, in the kingdoms of Golconda and Visiapour.

The spoils of animals, which live on the surface of the globe, are entitled to some consideration among the number of causes which we assign to explain the various changes our planet is subjected to. We find bones in a state of considerable preservation in certain places; we can even frequently enough distinguish the species of the animals to which they have belonged. From indications of this sort it is that some writers have endeavoured to explain the disappearance of certain species; and to draw conclusions thence, either that our planet is perceptibly cooled, or that a sensible change has taken place in the position of the axis of the earth. The phosphoric salts and phosphorus which have been found, in our time, in combination with lead, iron, &c. prove that, in proportion as the principles are disengaged by animal decomposition, they combine with other bodies, and form the mitric acid, the alkalies, and in general all the numerous kinds of nitrous salts.

In examining, then, the merits of the antagonist systems of geology now offered, we have no objection to confess that to the Huttonian belongs the praise of novelty, boldness of conception and unlimited extent of view. It aspires not only to account for the present appearances of the earth, but to trace a plan by which the formation of successive worlds is developed: it seeks to extend that order and arrangement, that principle of balance and restoration observed in all the departments of nature, to the constitution of the globe itself.

With this system the Neptunian forms a perfect contrast. It presumes not to carry its researches beyond the commencement of the present world, or to extend them beyond its termination. All the phænomena of geology conspire to prove that water has been the great agent by which rocks have been formed, and the surface of the earth arranged. It does not pretend to deny the existence of subterranean fires to a certain extent, or that many of the phænomena which strike us most forcibly may be the result of such an agency; but it does deny that such an agency is the grand or general cause of the geological facts and appearances that accost us on every side, and denies still farther that any such fire or beat can exist to an extent competent to such an extent. While the science remains in an imperfect state deficiencies may be found in the application of its general principle. But we discover no inconsistencies with that principle, nor con

tradictions to known and established truths.

More especially do we feel disposed to adhere to this last theory from its general coincidence with the cosmogony of the holy scriptures. The Mosaic account indeed restrains the process of creation and the period in which the waters covered the entire surface of the globe to a limit in which "if the terms be understood in their strict and literal sense, the existing phænomena of nature seem to evince that they could not possibly have occurred: for it confines the entire work of creation within the compass of six days, In another part of the scriptures, however, we have undeniable proofs that the term day, instead of being restrained to a single revolution of the earth around its axis, is used in a looser and more general sense, for a definite, indeed, but a much more extensive period: and we have as ample a proof from the book of nature, the existing face of the earth, that the six days or periods referred to in the Musaic cosmology imply epochs of

much greater duration than so many d'urnal revolutions as we have in the page of hu nan history, that the same terms were employed with the same laxity of meaning by the propher Daniel. Thus interpreted scepticism is driven from her fast and inmost fortress: every subterfuge is annihilated, and the word and work of the Deity are in perfect unison with each other. That the Creator might have produced the whole by a single and instantaneous effort is not to be denied: but as both revelation and nature concur in asserting that such was not the fact, it is no more derogatory to him with whom a thousand years are but as one day, and one day as a thousand years, to suppose that he allotted six thousand years to the completion of his design than that he executed it in six days. And surely there is something far more magnificent in conceiving the world to have progressively attained form, order,and vitality, from the mere operation of powers communicated to it in a state of chaos, or unfashioned matter, than in supposing the actual and persevering exertions of the Almighty for a definite, although a shorter period of time." Good's Life of Lucretius, p. lxxxi.”

GEOMANCY, GEOMANTIA, a kind of divination, performed by means of a number of little points or dots made on paper at random; and considering the various lines and figures which those points present, and thence forming a pretended judgment of futurity, and deciding. any question proposed. The word is of the Greek yn, terra, earth, and pavla,divination; it being the ancient custom to cast little pebbles on the ground, and thence to form their conjectures, instead of the points afterwards made use of. Polydore Virgil defines geomancy a kind of divination performed by means of clefts or chinks made in the ground, and takes the Persian Magi to have been the inventors of it. GEOMANTIC. a. (from geomancy.) Pertaining to the art of geomancy.

GEOMETER. s. (yours.) One skilled in geometry; a geometrician (Watts). GEOMETRĂ, in entomology. See PHA LENA.

GEOMETRAL. a. (geometral, French.) Pertaining to geometry.

GEOMETRICAL. GEOMETRIC. a. (yew

Prescribed or laid down by geometry. 3. Disxo,.) 1. Pertaining to geometry (More). 2. posed according to geometry (Grew).

GEOMETRICAL LINE or CURVE, called also algebraic line or curve, is that wherein the relations of the abscisses to the semiordinates may be expressed by an algebraic equation. See ALGEBRAIC CURVES.

Geometrical lines are distinguished into classes, orders, or genera, according to the number of the dimensions of the equation that and the abscisses: or, which often amounts to expresses the relation between the ordinates the same, according to the number of points in which they may be cut by a right line.

Thus, a line of the first order will be only a right line: those of the second, or quadratic order, will be the circle, and the conic sec. tions; and those of the third, or cubic order, will be the cubical and Nelian parabolas, the cissoid of the ancients, &c..

But a curve of the first gender (because a right line cannot be reckoned among the curves) is the same with a line of the second order; and a curve of the second gender, the same with a line of the third order; and a line of an infinitesimal order is that, which a right line may cut in infinite points; as the spiral, helicoid, the quadratrix, and every line generated by the infinite revolutions of a radius.

It is to be observed that it is not so much

When the series is infinite then the least term a is nothing, and the sum s=

thechoice of the lines for the construction of a

problem. The equation that expresses a parabola, is more simple than that which expresses a circle; and yet the circle, by reason of its more simple construction, is admitted before it. Again, the circle and the conic sections, with respect to the dimensions of the equations, are of the same order; and yet the circle is not numbered with them in the construction of

problems, but by reason of its simple description is depressed to a lower order, viz. that of a right line; so that it is not improper to express that by a circle, which may be expressed by a right line; but it is a fault to construct that by the conic sections, which may be constructed by a circle.

GEOMETRICAL PROGRESSION, a progression in which the terms have all, successively the same ratio: as 1, 2, 4, 8, 16, &c. where

the common ratio is 2.

The general and common property of a geometrical progression is, that the product of any two terms, or the square of any one single term, is equal to the product of every other two terms that are taken at an equal distance on both sides from the former. So of these terms,

1, 2, 4, 8, 16, 32, 64, &c.

1 x 64=2x32=4 × 16=8 × 8=64. In any geometrical progression, if denote the least term,

≈ the greatest term,

r the common ratio,

n the number of the terms,

s the sum of the series, or all the terms; then any of these quantities may be found from the others, by means of these general values, or equations, viz.

GEOMETRICAL PROPORTION, called also simply proportion, is the similitude or equality

of ratios.

Thus, if a:b::c: d, or a : bc:d, the also 6, 3, 14, 7, are in geometrical proportion, terms a, b, c, d, are in geometrical proportion; because 6:3:: 14: 7, or 6:3-14: 7. In a geometrical proportion, the product of the extremes, or 1st and 4th terms, is equal to the product of the means, or 2d and 3d terms. So

ad=bc, and 6×7=3×14=42.

cal.) According to the laws of geometry (Ray). GEOMETRICALLY. ad. (from geometriGEOMETRICIAN. s. (yet) One skilled in geometry; a geometer (Brown).

To GEOMETRIZE. v. n. (yilgew.) To act according to the laws of geometry (Boyle). GEOMETRY, the science or doctrine of extension, or extended things; that is of lines, surfaces, or solids.

The word is Greek, yura, formed of ye, or yn, earth; and upw, measure; it being the necessity of measuring the earth, and the parts and places thereof, that gave the first occasion to the invention of the principles and rules of this art; which has since been extended and applied to numerous other things; insomuch that geometry with arithmetic form now the general foundation of all mathematics.

Who were the first inventors of geometry is by no means certain. It is generally allowed that the Chaldeans were first possessed of the mathematical sciences, especially astronomy, which must imply geometry. Whether Abraham taught these from Ur of the Chaldees, as some learned men sciences first to the Egyptians, when he went assert, is not clear; but on this we may depend,

that the Egyptians were the first people that cultivated geometry, being compelled thereto by necessity, the mother of inventions, in order to ascertain to every man his legal property and estate, in a country where boundaries and land-marks were swept away and confounded by yearly inun dations.

That the Egyptians, in their ancient, free, monarchical state, were acquainted with some of the simple elements and easy problems in geometry, is not denied; but we cannot believe they made any great improvements in the abstruse parts thereof, since to Pythagoras (the famous philosopher of Samos, who flourished so low as about five handred and twenty years before Christ, and who had