Зображення сторінки

cal aid

N. AME- 3,000 miles from the sea, if we follow its numerous wind- marks the river-bottoms; and the superior excellence x svi RICA. ings, which are so remarkably serpentine and tortuous, of its navigation has made it the channel through which Rice

that from its junction with the Ohio to New Orleans at the various productions of the most extensive and fertile Geographi- its mouth, in a direct line, which does not exceed 460 parts of the United States are already sent to market. Gregorio cal details.

miles, the distance by water is more than 800 miles. At its commencement at Pittsport, or Pittsburg, it
The Mississippi has its origin in those parts of North takes a N. W. course for about twenty-five miles ;
America with which we are least acquainted, toward the then turns gradually to W.S. W.; and having pursued
W. of the northern United States and Canada; it re- that course for about 500 miles, winds to the S. W. for
ceives in its course the waters of the Illinois and Ohio, nearly 160 miles; then turns to the W. for about 260
and their various branches from the E. numerous streams miles more; thence S. W. for 160, and empties itself
which take their rise in the Rocky mountains, and form into the Mississippi in a S. direction, nearly 1,200
successively the Missouri, the Arkansaw, and the Red miles below Pittsburg. In times of high freshes, and
River westward (the latter a mighty stream, which has during the flow of ice and snow from the Alleghany
previously run 735 geographical miles in a direct line, and other mountains, vessels of almost any tonnage may
exclusive of its windings), and disembogues itself in the descend this river; it is never so low but that it may
gulf of Mexico, in W. Ion. 89°, N. lat. 28°. It generally be navigated by canoes, and other light crast, not draw-
affords fifteen feet of water, from the mouth of the Mis ing more than twelve inches water. The highest floods
souri to that of the Ohio; but, in time of Alushes, a are in spring, when the river rises forty-five feet; the
first-rate man-of-war may descend with safety. The lowest are in summer, when it sinks to twelve inches at
mean velocity of its current may be computed to be the bars, ripples, and shoals, where waggons, carts, &c.
four miles an hour. Its breadth is various, from one frequently pass over.
and a half to two miles; its mouth is divided into se The largest stream that flows into the Ohio is the Teasca
veral channels, which continually change their direction Tennesee river, whose remotest sources are in Virginia,
and depth. The Arkansaw has been recently explored N.lat. 37°, 10'. It runs about 1000 English miles S. and
by Major Pike, who computes its course, from its S. S. W., receiving considerable accessions of minor
junction with the Mississippi, about N. lat. 34°, 10', to waters on each side, and then turning circuitously
the mountains, at 1981 miles, and thence to its source, northward, blends itself with the Ohio at about 60
192 additional miles. It receives several rivers, navi- miles from the mouth of that river. It is navigable for
gable for upwards of 100 miles.

vessels of large burden to the distance of 250 miles from Missouri. The Missouri, which, with its eastern branches, wa its junction with the Ohio.

ters five-eighths of the United States, has not only The Alleghany river rises in Pennsylvania, on the Alte
claimed of late to rank as a distinct and equal stream western side of the Alleghany mountains; and after
with the Mississippi, but is sometimes described as running about 200 miles in a S. W. direction, meets the
receiving the latter at their junction. It rises in the Monongahela at Pittsburg, and the united streams now
Rocky mountains to the N. W. of Louisiana, in N. lat. form the Ohio. In this course it is increased by many
45° 24', and reckoning from its most extreme branch, tributary streams. Few rivers exceed the Alleghany
the Jefferson, joins the Mississippi after a course of for clearness of water and rapidity of current. It seldom
above 3,000 miles, in W. lon. 90°, and N. lat. 39o, fails to mark its course across the mouth of the Monon-
when, forming one mighty stream, they pursue their gahela, in the highest freshes or floods, the water of
way conjointly to the gulf of Mexico.

the latter being very muddy, that of the former very The Ohio, less sublime and majestic in its course clear. In high floods, the junction of these rivers prethan those already noticed, is also less interrupted sents a pleasing view; the Monongahela flowing somein its navigation. Its general breadth is about 600 times full of ice, the Alleghany transparent and free. yards; but it varies from 300 in the narrowest to Its banks are delightfully interspersed with cultivated 1,200 in the widest part. The course of the Ohio, farms and increasing towns. In a course of 80 miles, from Fort Pitt to its junction with the Mississippi, however, from a place called Envalt’s Defeat to Freeport, following all its windings, is, by Morse and other it is full of eddies, rapids, rocks, and other dangers, to American geographers, computed at 1,188 miles. This avoid which requires the utmost attention. In some of river commences at the junction of the Alleghany and the ripples the water runs at the rate of ten miles an Monongahela rivers. It has been described as, beyond hour; and a boat will go at the rate of twelve miles, competition, the most beautiful river in the world; its without any other assistance than the steering oar. meandering course through an immense region of the waters of this river are recommended by the forests; its elegant banks, which afford innumerable medical practitioners of Pittsburg, both for the purdelightful situations for cities, villages, and improved poses of bathing and of drinking; but the peculiar farms, with its various other advantages, well entitle it medicinal qualities of the Alleghany water are, perto the name originally given it by the French of “ La haps, more to be attributed to the faith of those who use belle Riviere.". Since that period, the Ohio has greatly it, than to any inherent character of superior salubrity. improved both in beauty and utility. The immense The Morongahela river rises at the foot of the # forests which once lined its banks have gradually Laurel mountain, in Virginia; thence, through various receded; cultivation smiles along its borders; numer- meanderings, passes into Pennsylvania, receiving in its ous villages and towns decorate its shores; and it is course the Cheat and Yougheogheny rivers, and many not extravagant to suppose that the time is not far smaller streams. It has already been stated that distant when its entire margin will form one continued this river unites with the Alleghany at Pittsburg: series of villages and towns. Vast tracts of fine country Twelve or fifteen miles from its mouth, it is about have communication with the Ohio, by means of its 300 yards wide, and is navigable for boats and small tributary navigable waters; extraordinary fertility, craft, particularly in autumn and spring, when it is

N. AME- generally covered with what are called trading and New York, where it empties itself into York bay, is N. AMEKICA. family boats; the former loaded with four, cider, almost uniformly S. Its whole length is about 250 RICA.

whiskey, apples, and various kinds of wrought ma- miles. tiro, raphi- terials; the latter carrying furniture, domestic uten The banks of Hudson, or North river, especially on the Geographinad drails,

cal details. sils, and agricultural instruments, destined for Kentucky western side, as far as the highlands extend, are chiefly and New Orleans.

rocky cliffs. The passage through the highlands, which Carcti Another principal river of North America, and the is sixteen or eighteen miles, affords a wild romantic

most considerable one in the eastern states, is the Con scene. In this narrow pass, on each side of which the
necticut. It rises in the highlands to the S. of New mountains tower to a great height, the wind, if there be
Brunswick, in W. lon. 720, and N. lat. 45°, 10'. After any, is collected and compressed, and blows continually
a lingering course of eight or ten miles, it has four as through a bellows; vessels, in passing through it, are
separate falls; and turning W. keeps close under the hills often compelled to lower their sails. The bed of this
which form the northern boundary of the vale through river, which is deep and smooth to an astonishing dis-
which it runs. The Amonoosack and Israel rivers, two tance, through a hilly, rocky country, and even through
principal branches of the Connecticut, fall into it from ridges of some of the highest mountains in the United
the E. between the latitudes 44o and 45°. Between the States, must undoubtedly have been produced by some
towns of Walpole on the E. and Westminster on the mighty convulsion of nature. The tide flows a few
W. side of the river, are the Great falls. The miles above Albany; to which place it is navigab
whole river, compressed between two rocks, scarcely sloops of eighty tons, and for ships to Hudson. About
thirty feet asunder, shoots with amazing rapidity 60 miles above New York the water becomes fresh, and
into a broad basin below. Over these falls, à is stored with fish of various kinds. The advantages which
bridge, 160 feet in length, was built in 1784, under this river affords to the inland trade of the state, and those
which the highest floods may pass without difficulty. which, by means of the lakes, it renders to the trade
This is the first bridge that was ever erected over this with Canada, are very great. These have been con-

Above Deerfield, in Massachusetts, it siderably enhanced since the invention of steam-boats, receives Deerfield river from the W. and Miller's river of which there are several, of amazing size, on this from the E. ; after which it turns westerly, in a sinuous river, on which that memorable invention was first course, to Fighting falls, and a little after tumbles over successfully tried, in the year 1807. Some of them, Deerfield falls, which are impassible by boats. At though equal in length to a ship of the line, travel Windsor, in this state, it receives Farmington river through the Narrows, and along the whole course from the W.; and at Hartford meets the tide. From of this river from New York to Albany, at the rate Hartford it passes on in a crooked course, until it of seven or eight miles an hour, against wind and falls into Long island sound, between Saybrook and tide. The distance, it is said, has been run down Lyme. The length of river, in a straight line; is nearly the stream in seventeen hours; formerly an uncertain 300 miles. It is from 80 to 100 rods wide, 130 miles voyage of three or four days, or even a week or two, from its mouth, where there is a bar of sand, which according to the state of the winds and tides. The considerably obstructs its navigation. On this beautiful average time is twenty-four hours. Ferry-boats, river, whose banks are peopled almost if not now propelled by steam, and so constructed that carentirely, to its source, stand numerous well-built riages drive in and out at pleasure, may be observed towns.

at every large town on this fine river. These conCharles Riter has its sources, five or six in number, venient vehicles are likely to supersede the use of in the state of Massachusetts, on the S. E. side of bridges on navigable waters. They are, in fact, a sort Hopkinton and Holliston ridge. The main stream of flying-bridge, with this advantage over the numerous runs N. E. then N. and north-eastwardly, round this and costly structures of that kind which now span ridge, until it mingles with Mother-brook. The river the broad surface of the Susquehannah, in the interior thus formed runs westward, passing over numerous of Pennsylvania—they do not require such expensive romantic falls. Bending to the N. E. and E. through repairs ; they may be secured from the effects of sudWatertown and Cambridge, and passing into Boston den foods; and, what is of far more importance, harbour, it mingles with the waters of the Mystic river they present no obstruction to navigation. at the point of the peninsula of Charlestown. It ing population of the fertile lands upon the northern is navigable for boats to Watertown, seven miles. branches of the Hudson must annually increase the

Taunton River rises in the Blue mountains, forming amazing wealth that is conveyed by its waters to New the principal drain of the country lying E. of those York. In almost every point of view, this river is one mountains. Its course is about 50 miles from N. E. of the greatest utility in the United States. to S. W.; and is navigable for vessels to Taunton. The Onondago river rises in a lake of the same Onondago. It finally empties into Narragauset bay, at Tiverton, name, and, running westerly, falls into lake OntaThe rivers Concord, Mystic, Medford, Ipswich, and many rio, at Oswego. With the exception of a fall, which others, contribute to the beauty and commercial inte- occasions a portage of twenty yards, this river is navirests of Massachusetts.

gable for boats from its mouth to the head of the lake; udson. To the state of New York belongs the noble stream thence batteaux go up Wood creek, almost to Fort

called Hudson River, and frequently North River. It Stanwix, whence there is a portage of a mile to Morises in a mountainous country, between the lakes On- hawk river. Towards the head waters of this river tario and Champlain. In its course, south-easterly, it salmon are caught in great quantities. approaches within six or eight miles of lake George; The Mohawk river rises to the northward of Fort Mohawk. then, after a short course E., turns southerly, and re- Stanwix, about eight miles from Sable river, a water ceives the Sacondago from the S. W. within a few miles of lake Ontario, and runs southerly 20 miles to the of the Mohawk river. The course of the river thence to fort; then eastward 110 miles, and, after receiving

The grow




N, AME- many tributary streams, falls into North river, by three the lakes Erie and Ontario, distant about eighteen x 200 RICA.

mouths, opposite to the cities of Lausinburg and Troy, miles from the town of Niagara, and situate upon a RICA)

from seven 'to ten miles N. of Albany. This is a very river of the same name. These falls may be regarded Geographi fine river, and is navigable for boats nearly the whole as presenting one of the most interesting of all the Corps of its course.

Its banks were formerly thickly settled phenomena in the natural world. “At Queenston," CH.. with Indians, but now cultivation and civilization have says Lieutenant Hall,* “ seven miles from the falls, rendered its course a busy scene of mercantile pur- their sound, united with the rushing of the river, is suit and increasing population.

distinctly heard. At the distance of about a mile, a The Dela The Delaware, the Susquehannah, Tyoga, Seneca, Ge- white cloud, hovering over the trees, indicates their ware, &c.

nesse, and the N. E. branch of the Alleghany river, situation : it is not, however, until the road energes all belong to the state of New York; and such is the from a close country into the space of open ground imintersection of the whole state, by the various branches mediately in their vicinity, that the white volumes of of these and other rivers, that there are few places, foam are seen, as if boiling up from a sulphureous throughout its whole extent, that are more than fifteen gulph. Here a foot-path turns from the road, towards or twenty miles from a navigable stream.

a wooded cliff. The rapids are beheld on the right

, The river Satunnah divides the state of Georgia from rushing, for the space of a mile, like a tempestuous South Carolina, and pursues a course nearly from A narrow tract descends about sixty feet down N. W. to S. E. The freshes of this river will some the cliff, and continues across a plasliy meadow, times rise from thirty to forty teet perpendicular above through a copse, encumbered with masses of lime the actual level of the stream.

stone; extricated from which, I found myself on the New Pisca 'The New Piscataqua, having four extensive branches, Table Rock, at the very point where the river precipitaqua.

all of them navigable for small vessels, furnishes the tates itself into the abyss. The rapid motion of the commencement of a line, which, drawn from its northern waters, the stunning noise, the mountain clouds, al. head, until it meets the boundary of the province of most persuade the startled senses, that the rock itself Quebec, divides New Hampshire from the province of is tottering, and on the point of rolling down into the Maine. The Merrimak, remarkable for two considerable gulf, which swallows up the mass of descending waters. falls, Amaskaeg, and Pantucket, bears that name from I bent over it, to mark the clouds rolling white beneath its mouth to the confluence of the Pernigewasset and me, as in an inverted sky, illumined by a most briliant Winipisiskee rivers, which unite in about lat. 43°, 30. rainbow,--one of those features of softness which NaThe first of these rivers forms the only port of New ture delights to pencil amid her wildest scenes, temHampshire. Great Bay spreads out from Piscataqua pering her awfulness with beauty, and making her river, between Portsmouth and Exeter.

very terrors lovely. Columbia.

Columbia Rirer is the principal stream that has been « There is a ladder about half a mile below the explored on the N. W. coast of America. It is called, Table Rock, by which I descended the cliff, to reach by the Indians, Tacoutche-Tesse, and is formed by in- the foot of the fall. Mr. Weld has detailed the imnumerable streams from the Rocky mountains, rising pediments and difficulties of this approach, and M. between the 43o and 53° of N. lat. The principal Volney confesses they were such as to overcome his stream has a course of 700 British miles to the ocean, exertions to surmount them. A few years, however, which it enters at N. lat. 46o.

have made a great change; the present dangers and Macken. Mackenzie's River is another noble stream, which has difficulties may be easily enumerated. The first is, the zie's river, lately become known to geographers

. It was originally ordinary hazard every one runs who goes up or down explored by Mr. Mackenzie, in 1789; and is first called a ladder; this is a very good one of thirty steps, or the Unjigu, or Peace River, which flows from the neigh- about forty feet; from thence the path is a rough one, bourhood of the Rocky mountains, in about lat. 56°, over the fragments and masses of rock which bare into the Lake of the bills, and afterwards under the gradually crumbled, or been forcibly riven from the name of the Slave river, proceeds in a N. W. direction cliff, and which cover a broad declining space, from to the Slave lake, whence it issues by the name of Mac- its base to the river brink. The only risk in this part kenzie's river, to what he has marked as the Arctic of the pilgrimage, is that of a broken shin from a false ocean, in W. lon. 135°, and N. lat. 69°, 14', after a step. The path grows smooth as it advances to the course of 1,700 miles.

fall, so that the updivided attention may be given to Cupper-mine River is only worth noticing in the same this imposing spectacle. I felt a sensation of awe as direction, as traced by Mr. 'Hearne, in 1771, to another I drew near it, like that caused by the first cannon on supposed point of the Arctic ocean, in 1130 W. lon. the morning of battle. I passed from sunshine into and upon about the same parallel on the mouth of gloom and tempest: the spray beat down in a heavy Mackenzie's river.

rain; a violent wind rushed from behind the sheet of Each of these streams, thus generally described, to water: it was difficult to respire, and, for a moment, give the reader some impression of the chief features it seemed temerity to encounter the convulsive workof this continent (and some of them being peculiar to no ings of the elements, and intrude into the dark dwelsingle district), will again receive our attention in their lings of their power : but the danger is in appearance alphabetical places.

only; it is possible to penetrate but a few steps behind Cataracts. Some of the chief wonders of this the curtain, and in these few, there is no hazard; the western hemisphere are found in its cataracts, or falls, footing is good, and the space sufficiently broad and which do not consist of single streams precipitated from free: there is not even a necessity for a guide; two bill to vale in picturesque beauty, as in the Alps, eyes amply suffice to point out all that is to be seen,

but of whole rivers tossed from broken mountains into or avoided.” Cataracts of immense basins below. The first in magnitude are Niagara. The Cataracts of Niagara, in Lower Canada, between

* Travels io Canada, 1817.



cal details.

[ocr errors]

The most stupendous of these cataracts is that on mill-dam. The banks of the river, immediately below. N. AMEICA. the British, or north-western side of the river Niagara, the falls, are about 100 feet high. From a noble bridge, RICA.

which, from its resemblance to the shape of a horse- erected in 1794 and 1795, the spectator may have a pophie shoe, has received the appellation of “ the Great, or grand view of the Cohez; but they have the most ro- Geographi-toilie Horse-shoe fall;” but this name is no longer strictly mantic and picturesque appearance from Lausinburg

applicable. It has become an acute angle, and the hill, about five miles E. of them. The river, immealteration is estimated at about eighteen feet in thirty diately below the bridge, divides into three branches, years. The height of this fall is 142 feet. But the which form several large islands. two others (for there are three falls, owing to the cir CANALS.—The rivers and lakes of North America Canals. cumstance of small islands dividing the river Niagara are in many places connected together by Canals, into three collateral branches) are each about 160 feet which furnish an artificial assistance to the communiin height. The largest has been reckoned at about cation established in other instances by Nature. The 600 yards in circumference. The width of the island, principal interior canals, which have been already which separates the “Great Fall” from the next in completed in the United States, are, the Middleser magnitude, is estimated at about 350 yards. The Canal, uniting the waters of the Merrimak river with second fall is said to be only five yards wide. The the harbour of Boston; and the canal Carondelet exnext island may be estimated at about thirty yards in tending from Bayou St. John to the fortifications or size; and the third, commonly called the “ Fort Schlo- ditch of New Orleans, and opening an inland commuper Fall," is about 350 yards. According to these nication with lake Pontchartrain. calculations, the islands being included, the entire extent On the 17th of April, 1816, and the 15th of April, of the precipice is 1,335 yards in width. It is supposed 1817, the state legislature of New York passed acts that the water carried down these falls amounts to no appropriating funds for opening navigable commuless a quantity than 670,255 tons per minute. A kind nications between the lakes Erie and Champlain and of white foam surrounds the bottom of “ Fort Schloper the Atlantic ocean, by means of canals connected with Fall," and rises up in volumes from the rocks : it does 'the Hudson river. This magnificent undertaking is not, however, as at the Horse Shoe fall, ascend above already begun, and promises to make effectual progress in the form of a cloud of smoke and mist, but the under the auspices of Governor Clinton. We have spray is so abundant that it descends like rain upon before us, at this moment, the official report of the the opposite bank of the river. The whirlpools and canal commissioners; but the extent and the capabilities eddies immediately below, are so dangerous as to of these works will be noticed at greater length, when render the navigation completely impracticable for six we come to speak of the physical resources of the miles. The river Niagara, above the falls, however, United States. is navigable by boats and canoes as far as Fort Chippa DESERTS.-North America does not furnish any of Deserts. way, which is about three or four English miles from those vast sandy deserts which occur with such frequency, them. But, on appreaching nearer, the waters are and spread to such an extent in Africa and Asia; for in such a state of agitation, as to require the boat or even in the most torrid regions of this continent there canoe to be kept in the middle of the stream, and, with- is so great an exuberance of water, as to be considered, out skilful management, would inevitably dash it to by some writers, as a sufficient proof of the theory of destruction. The middle of September is considered as its having recently emerged. the most pleasant time of the year for the examination CLIMATE.-America exhibits every variety of cli- Cllmate. of these celebrated falls, the surrounding forests being mate, every kind of soil, and almost every species of richly variegated with the autumnal colouring. At natural produce which the earth affords, besides many this season the traveller is not exposed to the danger animal and vegetable productions peculiar to this of meeting with noxious reptiles and insects of the quarter of the globe. Stretching through the whole country, which completely disappear in the chilly nights. width of the five zones, she feels the heat and cold St. Anthony's Falls

, in the river Missisippi, are situated of two summers and two winters every year. The about ten miles from the mouth of the river St. Pierre, heat of summer and the cold of winter are more inwhich joins the Missisippi from the W. These falls tense than in most parts of Europe. Fahrenheit's therwere first discovered by Louis Hennipin, in the year mometer, near Hudson's bay, sometimes rises in July 1680, and received their present name from that tra- to 85°, and sinks in January to 45° below zero. veller, who was the first European ever seen by the The severest cold is from the N.W.; but the prenatives in these parts. The river falls perpendicularly dominant winds are from the W. The middle proabove thirty feet, and is about 250 yards in width. vinces are remarkable for the variations of weather and The rapids, which are below, in the space of about the rapidity of its transitions. 300 yards, render the descent apparently greater It has been thought that, speaking generally, the when it is viewed at any considerable distance. These climate both of North and South America may be falls are so peculiarly situated as to be approachable stated to be coller than, considering its position on without any obstruction from a hill or precipice, and the globe, might be expected; to this a variety of the whole surrounding scenery is singularly pleasing. causes contribute. Among these may be reckoned,

The Cohez, or falls of the river Mohawk, between two with regard to the latter, the form of that continent, and three miles from its entrance into North river, are a which is exceedingly contracted in breadth in its apvery great natural curiosity. The river, above the proach towards cape Horn; so that for considerably falls, is about 300 yards wide, and approaches them more than one-third northwards of that extremity, it is from the N. W. in a rapid current, between the very narrow in comparison with the other divisions, and high banks on each side, and pours the whole body of the consequence of this tapering is an exposure to the its water over a perpendicular rock of about 40 feet winds which blow over that immense extent of ocean, in height, which extends quite across the river like a which stretches on either side, and southward to the

caldo ส


N. AME- Antarctic circle. Very much to the southward it is in North America, which fully illustrate this subject. N . RICA.

remarkable of these seas, that cold is prevalent lo a By clearing the land of its forests, and exposing the RICA.

greater degree than in similar parellels in the north, earth to the sun, its heat, at the depth of ten inches Geographi owing, doubtless, chiefly to the superior frigidity of below the surface, was ten or twelve degrees greater cai details.

the polar regions, whence the winds acquire their seve than that of the uncleared parts, which must, of course, rity. This remark, however, must be considered as influence the superincumbent atmosphere, so that both restricted in its application to the high latitudes. M. the earth and air experience an increased temperature Humboldt states, that this difference is not perceptible of ten or eleven degrees in the cultivated districts. And between the tropics, and very little so as far as the it is well known, that the climate of the United States 35th and 40th degrees of latitude. On the west- has materially improved since they have been under ern side of America, it is said, that generally the the hands of the diligent agriculturists, who have, from climate is more temperate and warm than on the time to time, within these few years, settled in every eastern, which is to be attributed to the ridge of moun- direction. Mr. Williams suggests, with very great protains forming a barrier against the colder winds that bability, that an amelioration of the climate of Europe assail the more exposed countries, and occasioning has taken place from a similar cause. Many of the those of a milder kind, and more adapted to the cli- great rivers which were formerly frozen over during mate, to diffuse their warmth and influence.

winter, now continue their course, unchecked to any Another cause conducing to the effect we have considerable degree, by the severity of the cold. The noticed, is the existence of mountains of such prodi- Euxine sea, which the Roman writers assure us was gious altitude and extent; and which, though in some anciently often covered with ice, at this period exhibits parts especially, they may form a shelter from the no such appearances; and consequently the improveinclement winds, that would otherwise sweep over a ment of the European climate, by about fifteen or sixconsiderable portion of the western side of the conti- teen degrees, may be attributed to the progress of culnent, contribute, nevertheless, in another point of view, tivation. to the general predominance of cold. The eternal MINERALS.—In the Apalachian mountains very dis- Pfizerie snows which are collected on their summits, must ne tinct strata are found. The central, or highest, is gracessarily refrigirate the atmosphere, and diminish the nite; the next schistose, and the exterior belts calcadegree of the temperature.

The granite is again divided into selspar, In estimating the causes of the comparative coolness pellucid or bluish quartz, and black mica. The we have mentioned, the very considerable elevation of schistose, although, in other regions, it is generally the surface of this continent must not be overlooked. metalliferous, here yields copper ore only; but in That the mean temperature of any place is materially Canada it contains lead, and, as some have attested, affected by its elevation, has been ascertained by un silver. The limestone, according to Mr. Pennant, conquestionable experiments, and for a reason which is tains petrifactions, particularly the cornu ammonis, a sufficiently obvious. Between the higher and lower small shell of the scallop kind, and several species of parts of the atmosphere, a perpetual intercommunica- corals. tion is carried on, the warm columns of air ascending In the primitive calcareous rock are likewise found from the surface whence they have received their heat, veins of granite, and sometimes whole banks of it. and a proportionable column, or stream, descending From its situation, it is obvious that it must have been from the upper regions. The space in which this ver contemporary in its deposition with the original rock. tical interchange takes place being several thousand Near Philadelphia, talc lies in large quantities, instead times smaller than the range of the horizontal currents of mica. Hornblende, quartz, and marble, are depowhich connect the equator with the poles, an equili- sited in veins like minerals. The granite mountains brium is produced, and the same absolute quantity of in America, unlike those of any other region, approach heat exists at every height in the atmosphere. But nearest the sea, but the rocks at a distance are chietly the capacity of air is affected by its density, otherwise calcareous, and breccia and argillaceous schistus somean uniform temperature would prevail throughout the times are deposited over the red primitive limestone. vertical column; and the power of containing heat, Calcareous rocks guard and surround the lakes of increasing as the density is diminished, the temperature Upper Canada; whilst from Montreal to the sea, the of the higher regions of the atmosphere is reduced in granite is the chief component. At the island of St. proportion; so that the temperature at any given ele- Helena, on the coast of Carolina, the mountains are vation, is in the inverse ratio of the capacity for re- chiefly of granite; and in the mountain of Beloeil is taining heat in the air of such density. Hence we found much black schorl. The black slate mentioned have å formula for expressing the diminution of tem- by the Duc de Rochefoucault, is the same as the black perature in the perpendicular ascent, and though the schistose limestone of Kalm, a Swedish traveller and gradation is not precisely uniform, owing to certain a most skilful naturalist. Grey granite and schorts local peculiarities and influences, the decrease is more compose the rock of Quebec, and from the quartz rapid in the superior regions.

crystals which were found there, this rock is some There is yet another consideration which has been times called the Rock of diamonds. In this neighvery fully elucidated by some writers, with regard to bourhood limestone and granite are intermingled; the the North American continent, and which is also ap- slaty stone strikes out through the unpaved streets of plicable to the Southern division The uncultivated Quebec to the frequent annoyance of the traveller; but state of a country is believed considerably to affect the the grey granite stone of the vicinity has furnished many climate, and in both regions immense tracts remain noble buildings, of late years, to the town. The bank wholly uncleared, being covered with forests, marshes, of Newfoundland has been considered as a rock of and mountains. Some very interesting estimates have granite, covered with sand. In the vicinity of Bosbeen made from actual experiment by Mr. Williams, ton and New York a soft granite is found in rocks, ia

« НазадПродовжити »