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the beight of the pole at Paris, going from thence tinues above the horizon, until they come to one directly northwards, till he came to the place where the longest day is 15 of ours or half a month; where the height of the pole was one degree inore and from this to the pole they count by the inthau at that city. The length of the way was mea- crease of half-months or whole months, the clisured by the number of resolutions made by one mates enrling at the poles where the days are six of the wheels of his carriage ; and, after proper months long. The climates betwixt the equator allowances for the declirities and turnings of the and the polar circles are called hoor climates, and road, he concluded that 68 Italian miles were equal those belween the polar cirrles and the poles are to a degree on the earth.

called month climates. In cominon language, According to these methods, many other mea. however, we take the word climate in a very differsurements of the earth's circumference have since ent sense ; so that when two countries are said to that time been made, with inuch greater accuracy. be in different elimates, we understand only that See DEGREE and EARTH.

the temperature of the air, seasons, &c. are dif. Though the inaps of Eratosthenes were the best ferent. See CLIMATE. of his time, they were yet very imperfect and in- From the difference in the length and positions accurate. They contained little more than the of the shadows of terrestrial substances, ancient states of Greece, and the dominions of the succes- geographers have given different terms to the insors of Alexander, digested according to the sur. habitants of certain places of the earth; the rea. veys above mentioned. He bad indeed seen, and son of which will be easily understood from the has quoted, the voyages of Pythias into the great following considerations : i. Since the sun in his Atlantic ocean, which gave bir some faint idea of apparent annual revolution never removes farther the western parts of Europe ; but so imperfect, from the equator than 25 degrees, it follows, that that they could not be realized into the outlines none of those who live without that space, or beof a chait. Strabo says he was very ignorant of yond the t'ropics, can have the luninary vertical Gaul, Spain, Germany, and Britain, and he was to them at any season of the year. 2. All who equally ignorant of Italy, the coasts of the Adria- live between the tropics have the sun vertical twice tic, Pontus, and all the countries towards the north. a year, though not all at the same time. Thus, to

Such was the state of geography, and the nature those who live directly under the equator, he is of the maps, before the time of Hipparchus. He directly vertical in March and September at the made a closer connection between geography and time of the equinox. If a place is in 10° north astronomy, by determining the latitudes and lon- latitude, the sun is vertical when he has 10° north gitudes from celestial observations. From his declination, and so cf every other place. 3. Alt time nothing of any consequence to deserve record- who live between the tropics have the sun at noon ing occurs till about 150 years after Christ, when sometimes north and sometimes south of them. Ptolemny composed his system of geography. The Thus those whu live in a place situated in 20°.north chief materials he employed in composing this latitude have the sun at doon to the northward work, were the proportions of the gnomon to its when he has more than 20 degrees north declinashadow, taken by different astronomers at the tion, and to the southward when he has less. 4. times of the equinoxes and solstices; calculations Such of the inhabitants of the earth as live withfounded on the length of the longest days; the out the tropics, if in the northern hemisphere, measured or computed distances of the principal have the sun at noon to the southward of them, roads contained in the Roman itineraries and sur- but to the northward if in the southern hemiveys; the various reports of travellers and navio sphere.-1. Hence when the sun is in the zenith of gators; and the works of preceding authors, par- any place, the shadow of a man or any upright ticularly Strabo, who published under Augustus. objects falls directly upon the place where they *All these were compared together, and digested stand and consequently is invisible ; whence the into one uoiform body or system. This system, inhabitants of such places were called Ascii, or however, was very imperfect, containing some without shadows. 2. Those who live between the 'great crrors, which are pointed out in Blair's His- tropics, and have the sun sometimes to the north tory of Geography : nevertheless it continued in and sometimes to the south of them, have of convogue till the last three or four centuries, within sequence their shadows projecting north at some which time, the great improvements in astronomy, seasons of the year, and south at others, whence the discoveries of new countries by navigators, thev were called An:phiscii, or having two kinds and the progress of commerce and of arms, have of shadows. 3. Those who live without the tropics contributed to a very great degree of perfection. have their noon-shadows always the same way,

From an observation of the diversity in the and are therefore called Heteroscii, that is, having length of the days and nights, the rising and set- only one kind of shadow. If they are in north lating of the sun,with the sther phenomena, the an- titude, the shadows are always turned towards the tient geographers divided the surface of the earth north, and if in the southern hemisphere, towards into certain districts, which they called climates; the south. 4. When a place is so far distant from and instead of the method of describing the situ- the equator that the days are 24 hours long, orlongation of places by their latitude and longitude as er, the inhabitants were called Periscii, because we do now, they contented themselves with men. their shadows turn round tièm. tioning the climate in wbich they were situated. Names have likewise been imposed upon the in

This method of dividing the surfuce of the earth habitants of different parts of the earth from the into climates, though now very much disused, has parallels of latitude under which they live, and been adopted by several inodern geographers. their situation with regard to one another. 1. Some of these begin their climates at the equator, Those who lived at distant places, but under the reckoning them by the increase of half an huur in same parallel, were colled Periæci, that is, living the length of the day northward. Thus they go in the same circle. Some writers, however, by the on till they come to the polar circles, where the name of Periæci distinguish those who'live under longest day is 24 hours: betwixt these and the opposite points of the same parallel, where the poles they count the climates by the increase of a noon of one is the midnight of the other. 2. When natural day in the length of time that the suo con- two places lie goder parallels equally distant from VOL. V.

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the equator, but in opposite hemispheres, the in- lection of waters surrounding a considerable part habitants were called Autæci. These have a simi- of the continent; as the Atlantic. A sea is a lar increase of days and nights, and similar seasons, sinaller collection of waters; as the Black Sea. A but in opposite months of the year. According to gulf is a part of the sea which is nearly surroundşome, the Antæci were such as lived und«r the ed with land; as the guit of Venice, A bay has a same geographicalmeridian, and had day and night wider entrance than a gulf; as the Bay of Biscay. at the same time. 3. If two places are in parallels A strait is a narrow passage that joins two seas; equally distant from the equator, and in opposite as the Strait of Gibraltar, wbich joins the Medie meridians, the inhabitants were called Antipodes, terranean to the Atlantic. A lake is a large col

at is, having their feet opposite to one another. lection of water entirely surrounded by land, When two persons are Antipodes, the zenith of having no visible communication with the sea; as the one is the nadir of the other. They have a the Caspian Lake in Asia. A river is a stream of like elevation of the pole, but it is of different water that has its source from a spring, which poies; they have also days and nights alike, and keeps continually running till it falls into some similar seasons of the year, but they have opposite other river, or into the sea. hours of the day and night, as well as seasons of The ancients, considered the globe under the the year. Thus when it is midday with us, it is three grand divisions of Asia, Europe, and Africa. midnight with our Antipodes; when it is summer Here the distinctions were arbitrary, as they often with us, it is winter with them, &c.

included Egypt under Asia, and they had not disFroin the various appearances of the sun, and covered the limits of Europe towards the N. E. the effects of his light and heat upon different Modern discoveries have added a fourth division, parts of the carth, the division of it into zones has that of America, which exceeiling even Asia in arisen. These are five in number. 1. The torrid size, might bave been admitted under two grand zone, lying between the two tropics for the space and distinct denominations, limited by the ischinus of 47° of latitude. This is divided into two equal of Darien. Till within these last thirty years it parts by the equator. 2. The two tenperate was supposed that a rast continent existed in the zones lie between the polar circles and the tropics, south of the globe; but the second navigation of containing a space of 43° of latitude. And, 3. captain Cook dispelled the idea, and demonstrated The two frigid zones lie between the polar circles that if any continent existed there, it must be ia and the poles. In these last the longest day is ile- the uninhabitable ice of the south pole. The vast ver below 24 hours; in the temperate zones it is extent of New Holland rewarded the views of the derer quite so much, and in the torrid zone it is enterprize; this, which seems too large to be ranknever above 14. The zones are named from the ed among islands, and too small for a continent, degree of heat they were supposed to be subjected eludes the petty distinctions of man: and while to. The torrid zone was supposed by the ancients geographers hesitate whether to ascribe it to Asia, to be uninhabitable, on account of its heat; but or to denominate it a fifth specific division of the this is now found to be a mistake, and many parts earth, it is not improbable that the popular divie of the temperate zones are more intolerable in this sion of four quarters will still predominate over all respect than the torrid zone itself. Towards the speculative discussions. polar circles also these zones are intolerably cold Of the grand divisions of the earth, Asia has during the winter season. Only a small part of the ever been esteemed the most populous; and is northern frigid zone, and none of the southern, is supposed to contain five hundred millions of souls, inhabited. Some geographers reckoned six zones, if China, as has been averred by the latest writers, dividing the torrid zone into tiro by the equator. comprizes three hundred and thirty millions. The

The natural division of the surface of the globe population of Africa may be estimated at thirty is into sea andland; about three-fourths of the whole millions, of America at twenty millions, and one being oecupied by water, although probably no hundred and Gity inillions may perhaps be assigne where to a depth comparatively very considerable, ed to Europe. at most, of a few miles on an average. The re. We cannot observe any general symmetry in maining ivurth consists of laids, elevated more or the distribution of the earth's surface; excepting less above the level of the sea, interspersed, in that the two large continents of Africa and South some parts, with smaller collections of water, at America have some slight resemblance in their various heights, and in a few instances, somewhat forms, and that each of them is terminated to the lower than the general surface of the main ocean. eastward by a collection of numerous islands. Thus the Caspian Sea is said to be about three hun. The large capes projecting to the southward have dred feet lower than the ocean ; and in the interior also a similarity with respect to their forin, and parts of Africa there is probably a lake equally the islands near them; to the west the continents de pressed.

are excavated into large bays, and the islands are Hence arise the following technical terms: A to the east: thus Cape llorn has the Falkland continent is a large portion of the earth, which Islands; the Cape of Good Hope, Madagascar; comprehends several countries that are not sepa- and Cape Comorin, Ceylon to the east. rated by any sea; such are Europe, Asia, Africa, The great continent, composed of Europe, Asia, and America. An island is a part of the earth and Africa, constitutes alsout a seventh of the which is entirely surrounded by water; as Great whole surface of the earth; America about a sixBritain. A peninsula is a tract of land almost teenth; and Australasia, or New South Wales, sufounded with water, and is joined to a conti- about a fifcieth ; or in hundredth parts of the dient only by a narrow slip or acck; such is the whole, Europe contains two; Asia, seven; Africa, Morea iu Girece. An isthmus, or neck of and, six; America, six; and Australasia, two; the reis that part by which a peninsula is joined to a maining seventy-seven being sea; although some Kortinent, or two continents together; as the authors assign seventy-two parts only out of one is hinus of Suez, which joins Africa to Asia. A hundred to the sca, and twenty-eight to the promontory, or cape, is a high part of land which land, utches into the sea; thus the Cape of Good These proportions may be ascertained with to11 pe is a promoutory. An uccan is a vast culo Icrable accuracy, by weighing the paper nade for covering a globe, first entire, and then cut out ac. ing from the extremity of Caucasus, to Cape Cocording to the terminations of the different coun- morin. in Africa, Mount Atlas extends from Fez tries; or, if still greater precision were required,' to Egypt, and the mountains of the Moon run the greater parts of the continents might be divid=" nearly in the same direction : there is also a coned into known portions of the whole spherical sur- siderable elevation between the Nile and the Red face, and the remaining irregular portions only Sea. In the new world, the neighbourhood of the weighed.

western coast is the most eleratert; in North Tbe general inclinations and levels of the contie America, the Blue Mountains, or Stony Mounnents are discovered by the course of their rivers. tains, are the most considerable; and the moupOf these the principal are, the rivers of the Ama-' tains of Mexico join the Andes or Cordeliers, zons, the Senegal, the Nile, the river St. Law.' which are continuerl along the whole of the west rence, the Hoangho, the river La Plata, the Jeni- coast of South America. sei, the Mississippi, the Volga, the Oby, the There are sereral points in both hemispheres, Amur, the Oronooko, the Ganges, the Euphrates, from which we may observe rivers separating to the Danube, the Duo, the Indus, the Dnieper, and run to different seas; such are Swisserland, Bjelothe Dwina; and this is said to be nearly the order sero, Tartary, Little Tibet, Nigritia or Guinea, of their magnitudes. But if we class them accord, and Quito. The highest mountains are Chimboing to the length of the country through which raçao, and some others of the Cordeliers in Petu, they run, the order will, according to Major Ren. or perhaps Descabesado in Chili, Mont Blanc, and nel's calculation, he somewhat different; taking the peak of Teneriffe. Chimboraçao is about the length of the Thames for unity, he estimates seven thousand yards, or nearly four miles, above that of the river of Amazons, at 15); the Kian the level of the sea ; Mont Blanc, five thousand, or Krw, in China, 15}; the Hoango, 13;; the Nile, nearly three miles; the Peak of Teneriffe about 12; the Lena, 111; the Amar, 11; the Oby, 103; four thousand, or two miles and a quarter; Ophir, the Jenisei, 10; the Ganges, its companion the in Sumatra, is said to be five or six hundred feet Burrampooter, the river of Ava, and the Volga, higher. It has, however, been asserted, that sume each 91; the Euphrates, 8); the Mississippi, 8; of the snowy moantains to the north of Bengal the Danube, 7; the Indus, 51; and the Rhine, 5 are higher than any of those of South America.

We may form a tolerably accurate idea of the The plains of Quito, in Peru, are so much elevated, levels of the ancient continent, by tracing a line that the barometer stands at the height of fifteen across it in such a direction as to pies no river, inches only, and the air is reduced to half its usual which will obviously indicate a tract of country density. But none of these heights is equal to a higher than most of the neighbouring parts. Be- thousandth part of the earth's semi-diameter, and ginning at Cape Finisterre, we soon arrive at the the greatest of them might be represented on a sixPyrennees, keeping to the south of the Garronne, inch globe by a single additional thickness of the and tbe Loire.

paper with wbich it is covered. Monnt Sinai, in After taking a long turn northwards, to avoid Japan, Mount Caucasus, Etna, the Southern Pythe Rhine, we come to Swisserland, and we may renees, St. George among the Azores, Mount approach very near to the Mediterranean in the Adam in Ceylon, Atlas, Olympus, and Taurus, state of Genoa, taking care not to cross the are also high mountains; and there are some very branches of the Po. We make a circuit in Swis. considerable elevations in the island of Owyhee. serland, and pass between the sources of the Da.: Ben Nevis, in Scotland, is the loftiest of the British nube, and of the branches of the Rhine, in Swabia. hills, but its height is considerably less than a Crossing Franconia, we leave Bohemia to the mile. north, in order to avoid the Elbe; and coming The most elevated mountains, excepting the acar to the borders of Austria, follow those of Hun- summit of volcanos, consist of rocks, more or less gary to the south of the Vistula. The Dnieper mixed, without regular order, and commonly of then obliges us to go northwards through Lithua- granite or porphyry. These are called primary nia, leaving the Don wholly to the right; and the mountains; they ran generally from cast to west Volga, to pass still further north, between Peters in the old world, and from north to south in the burg and Moscow, a little above Bjelosero. We new; and many of them are observed to be of may then go eastwards to the boundary of Asia, easier ascent on the east than the west side. The and thence northwards to Nova Zembla. Hence secondary mountains accompany them in the we descend to the west of the Oby, and thence to same direction; they consist of strata, mostly the east of the branches of the Volga, and the calcareous and argillaceous, that is, of the nature other inland rivers flowing into the lake Aral and of lime-stone and clay, with a few animal and vethe Caspian Sea. Here we are situated on the gerable remains, in an obscure form, together with widely-extended elevation of India, in the neigh- sait, coals, and sulphur. The tertiary inuuntains bourhood of the sources of the Indus; and, lastly, are still smaller; and in these, the animal and re. in our way from hence towards Kainschatka, ne getable remains are very abundant; they consist lease the Jenisei and Lena on the left, and the chietly of lime-stone, marble, alabaster, buildingGanges, Kiang Kew, the Hoangho, and the Amur, stone, mill-stone, and chalk, with beds of Dint. to the right.

Where the secondary and tertiary mountains are The direction of the most conspicuous moun- intersected by valleys, the opposite strata often tains is, however, a little different from this; the correspond at equal heights, as if the valley's had principal obain first constitutes the Pyrennees, been cut or washed from between them; but comeauddivides Spain from France, then passes through times the mountains have their strata disposed as the Vivarais and Aurergne, to join the Alps, and if they had been elevated by an internal force, and through the South of Germany to Dalmatia, Alba- their summits had afterwards crumbled away, the nia, and Macedonia; it is found again beyond the strata which are lowest in the plains being highest Euxine, under the names of Taurus, Caucasus, in the mountains, The strata of th' se mountains and Imaus. and goes on to Tartary, and to Kane are often intermixed wiib veins of metal, running schatka The peninsula of India is divided froin in all possible directions, and occupying yacujties north to south by the mountains of Gate, extend- which appear to be of somewhat later date than

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the original formation of the mountains. The The Moravian accounts of their Mission in the volcanic mountains interrupt those of every other interior of America : with the Voyages of Ansons description, without any regularity, as if their ori. Byron, Cooke, Phipps, Bligh, Wilson, Walus, La gip were totally independent of all the rest. Peyrouse, Perron, &c. (Blair, Gregory, Hutton,

The internal constitution of the earth is very Nicholson, Pinkerton). little known from actual observation, for the depths GEOLOGICAL. a. (from geology.) Reto which we have penetrated are comparatively lating to the subject of geology. very inconsiderable, the deepest mine scarcely de- GEOLOGY: (from yn, the earth, and noyos, scending half a mile perpendicularly. It appears a discourse, or treatise.) That part of natuthat the strata are mure commonly in a direction ral philosophy wbich treats of the structure of nearly horizontal, than in any other; and their the earth, in regard to the origin, composition, thickness is usually almost equable for some dis- and decomposition of its sulid contents. Thus tance; but they are not disposed in the order of explained, mineralogy should seem to be a branch their specific gravity, and the opinion of their fol- of geology: but the former term has of late lowing each other in a similar series, throughout years been carried to such an extent by the most the greater part of the globe, appears to rest on popular mineralogist of his day, M. Werner, as te very slight foundations.

include not only geology, properly so called, but Among the moderns, the chief authors on the every thing immediately connected with it: the subject of Geography are Johannes de Sacrobosco, situation of the materials constituting the solid or John Hallifax, who wrote a Treatise on the contents of the earth, so far as we have been able sphere : Sebastian Munster, in his Cosmographia to examine them, as well as their mode of origin, Universalis, in 1559; Clavius, on the sphere of and the veins by which they are intersected. And Sacrobosco; Piccioli's Geographia et Hydro gra- hence, in the Wernerian system, geology becomes phia Reformata ; Weigelius's Speculum Terræ; a branch of mineralogy; and, in order to prevent De Chales's Geography, in his Mundus Mathema- coufusion, from the subjection of what has hi. ticus; Cellarius's Geography; Cluverius's Intro- therto been regarded as a classific term to an or. ductio in Universam Geographiam; Leibnecht's dinal station, the word geognosy has been invented Elementa Geographiæ Generalis ; Stevenius's to supply its place. See MINERALOGY. Compendium Geographicum ; Wolfius's Geogra- The object of geology, then, is to unfold the phia, in his Elementa Matheseos ; Busching's structure of the globe; to discover by what causes New System of Geography; Gordon's, Salmon's, its parts have been arranged; from what operaand Guthrie's Grammars; Adams's Geography, tions have originated the general stratification of ancient and modern; and Pilkington's Geograpby, its materials, the inequalities with which its surlately published in two vols. 4to., with an intro- face is diversified, and the immense number of duction by Mr. Vince. But, as an excellent scien- different substances of which it is composed. tific work, we must not omit Varenius's Geogra- In pursuing this investigation, many difficulties phia Generalis, with Jurin's additions: we really occur to us. The bare surface or mere crust of wish some gentleman of talents would publish a the solid substance of the earth is the whole that new edition of this admirable work, suited to the we are capable of boring into, or of acquiring a present state of the science. Dr. Playfair has re- knowledge of, even by the der pest clefts of volcacently published a system of Geography, which is,. noes, or the bottoms of the deepest seas. It is in many respects, a valuable performance. not often, however, that we have a possibility of

In studying particular Geography, recourse must examining either seas or volcanoes at their botbe had to voyages and travels: the collections tom: the inhabitable part of the globe bears but of Mavor, and that by Pinkerton now publishing, a small portion to the uninbabitable, and the may be safely recominended. We must also chvilized an infinitely smaller proportion sull. mention

Hence, our experience must be necessarily exPennant's Tours in Britain.

tremely limited; a thousand facts may be readily Young's Tours in the British Isles.

conceived to be unfolded that we are incapable of Saintfond's Travels in England and Scotland. accounting for, and a variety of systems that sball, Holcroft's Tour in France.

nevertheless, aim at an explanation. Spallanzani's Travels in the Two Sicilies.

So far as the superficies of tbe earth has been Coxe's Travels in Russia, &c.

laid open to us by ravines, rivers, mines, &c. we Porter's in Do.

find it composed of stony masses, sometimes simPallas's Travels in the Russian Empire. ple, as lime-stone, serpentine, or quartz; but more Carr's Northern Summer, and his other volumes frequently compound, or composed of two or more of Travels.

sin.ple materials, variously mixed and united to. Staunton's Account of China.

gether, as granite, which is a composition of Barrow's Travels in China.

quartz, felspar, and mica. These stony masses, Percival's Account of Ceylon.

or rocks, are numerous, and they appear to be Cordiner's Do.

laid one over the other, so that a rock of one kind Symes's Embassy to Ava,

of stune is covered by another species of rock, Collins's Account of New South Wales.

and this by a third, and so on. In this superpoBruce's Travels in Abyssinia.

sition of rocks, it is easily observable, that their Barrow's Tmvels in Africa.

situation is not arbitrary: every stratum occupies Park's Travels in the Interior of Africa.

a determinate place, so that they follow each Brouk ne's Travels in Africa.

other in regular order from the deepest part of Sonnini's Travels in Egypt.

the earth's crust, which has been examined, to the Acerbi's Journey to the North Cape.

very surface. Thus there are two things respectPercival's Cape of Good Hope.

ing rocks, that peculiarly claim our attention; Mackenzie's Journey in North America. their composition and their relative situation. Davis's Travels in America.

But, besides the rocks which constitate the earth's Pinckard on the West Indies.

crust, there are other masses which must also be Mackinapn's Tour in the West Indies. considered. These traverse the rocks in a different

cause.

direction, and are known by the name of veins, as extremely slow, yet from the declivity of the land if the rocks had split asunder in different places it must necessarily take place, and may, therefrom top to bottom, and the chasins had been fore, be admitted as an uniformly operating aftertards filled up with the matter which constitutes the veio.

2. It is further assumed, that at certain depths Independently of the substances thus presented in the mineral regions an immense heat is con. to us, we meet with facts that prove most deci- stantly present; a heat which operates in the fusively that the general mass has undergone va. sion and consolidation of the substances deposited rious revolutions at various times, and revolutions in these regions. To the action of this subterra not only of great antiquity, but of universal ex- Deous fire the formation of all our strata is attritent. We have the most unexampled proof, that buted, for by this they are again sublimed, and its whole surface has been covered with ocean, and exposed to view in different states of combination that every part of it has suffered change; moun- and perfection. These strata, therefore, consist taius have been raised, plains levelled, islands se- of the wrecks of a former world, which have been parated from a continent, and the waters collected more or less completely fused by this agent, and so as to leave an elevated land. We find it difs by subsequent cooling have been consolidated. ficult to conceive causes adequate to the produc- The subterraneous fire to which these effects tion of such effects; and operations so immense are ascribed is conceived to operate under the seem too remote from any means of investigation modification of compression, in consequence of which we possess, to admit of being explained. which, from various facts appealed to, and to a

One point, however, in the midst of all the in- certain extent confirmed by some very valuable tricacy that surrounds is still remains decided, experiments by sir James Hall, (provided those exthat the shell of the globe has, at some period or periments should bear the test of farther enquiry) other, been in a state of Anidity, and that from it seems pretty clearly ascertained, that when this circumstance has arisen its present arrange. certain gasses appertaining to the fusible subment. Now the only two causes that can enter stance, as carbonic acid for example, are renderinto the mind of man as being competent to such ed incapable of flying off, a much less quantity an effect are the operation of fire or of some solvent: of actual heat is sufficient for the purpose of fuand hence our researches become in some degree sion, than when such gasses, freed from a heavy limited to the inquiry by which of these means superincumbent pressure, have a possibility of this effect has been induced. If a solvent have escaping. Now the subterraneous fire being been the cause, that solvent must have been wa- placed at immense depths, the substances on which ter, for there is no other Auid in nature in suffi. it operates must be enormously compressed; cient abandance to have acted the part of a solve which compression will prevent their volatilizaent upon a scale so prodigious.

tion in whole or in part: and from this circumHence, then, two distinct theories arise, which stance it is possible, we are told, to explain apappear to have been agitated with considerable pearances and qualities in minerals, and to answer warmth in former times, but with a much greater various objections, which would otherwise weigh dezret of warmth, and much deeper view of the heavy against the hypothesis. subject, in the present day. Is the present struc- - 3. The elevation of the strata is in like manner ture of the solid contents of the earth, so far as it the result of this same subterraneous heat: and it is capable of examination, the result of igneous is contended that nothing but the extensive and fusinn, or of aqueous solutiun? Is the Plutonic forcible power which is hereby produced can be or the Neptunian system founded on the strongest fairly conceived adequate to such an effect. basis? In ancient times Heraclitus took the lead The first of these positions is not very objectionas to the former: and Thales, or rather, perhaps, able, and as far as relates to its general principle, Epicuris, as to the latter. In our own day, separated from the positions with which it is conthough the Plutonic theory was first started by nected, may be admitted. It may be allowed by M. Buffon, its defenders are now chiefly confined the Neptunian as well as by the Plutonic geolo- . to our own country, and consist of Dr. Hutton, gist, that the strata of the earth are liable to professor Playfair, and very lately of sir James waste, and that the materials are carried forward Hall; names unquestionabiy highly respectable, to the sea: but the appearance of lime-stones and en it.ed to every deference, but most power and marbles containing shells, in which the sparry fully opposed by the respectable authorities of structure is as perfect as it is in the primary limeWerner, de Saussure, and Kirwan, not to mention stone, and in which are distributed veins of crythat the ceneral voice of geologists is very consi- stallized carbonat of lime, this, and a variety of derably in favour of the Neptunian theory, or facts like this, must at all times militate fatally that entertained by the last-mentioned philoso- against the agency of fire in the production of such phers.

sparry structure, and such veins of crystallization; Plutonic Theory.-1. According to this system for in every instance in which it is found sufficient there is in the substance either of the entire globe, to produce such a structure, it must necessarily or throughout the entire crust of it with which we have destroyed every vestige of the structure of are acquainted, a regular series of decay and re- the shells, and have altogether dissipated the car. novation, and the processes by wbich these are bonic acid, necessary for the veins of crystallized affected have an uniform relation to each other. carbonat of lime. The hardest rocks are worn down by air and wa- Against the second position the objections are ter, causes which, however slowly they may ope. indeed strong, and, if we mistakenot, insuperable. rate, are constant in their action, and which, “It is not fire, says Mr. Playfair, in the usual therefore, in indefinite time, must be equal to the sense of the word, but heat, which is required for production of the greatest effect. From the figure this purpose: and there is nothing cbinierical in of the surface of the earth, the decayed materials supposing that nature has the means of producing must be carried towards the ocean, and ultimately heat, even in a very great degree, without the deposited in its bed. This transportation may be assistance of fuel, or of vital air. Friction is a impeded by local causes, or pay, in general, be source of beat, volimited, for what we know, in

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