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in two different places, at basins of water of unknown extent, and which I should judge to be nearly on a level with the water of the river; however, I do not think they are formed by refluent water from that, because they are never turbid; because they do not rise and fall in correspondence with that in times of food, or of drought; and because the water is always cool. It is probably one of the many reservoirs with which the interior parts of the earth are supposed to abound, and which yields supplies to the fountains of water, distinguished from others only by its being accessible. The vault of this cave is of solid lime-stone, from 20 to 40 or 50 feet high, through which water is continually percolating. This, trickling down the sides of the cave, has incrusted them over in the form of elegant drapery ; and dripping from the top of the vault generates on that, and on the base below, stalactites of a conical form, some of which have met, and formed massive columns,

Another of these caves is near the North mountain, in the county of Frederick, on the lands of Mr Zane. The entrance into this is on the top of an extensive ridge. You descend 30 or 40 feet, as into a well, from whence the cave then extends, nearly horizontally, 400 feet into the earth, preserving a breadth of from 20 to 50 feet, and a height of from 5 to 12 feet. After entering this cave a few feet, the mercury, which in the open air was at 50°. rose to 57o. of Fahrenheit's thermometer, answering to 11o. of Reaumur's, and it continued at that to the remotest parts of the cave. The uniform temperature of the cellars of the observatory of Paris, which are ninety feet deep, and of all subterranean cavities of any depth, where no chymical agents may be supposed to produce a factitious heat, has been found to be 10°. of Reaumur, equal to 54 1-2°. of Fahrenheit. The temperature of the cave above mentioned so nearly corresponds with this, that the difference may be ascribed to a difference of instruments.

At the Panther gap, in the ridge which divides the waters of the Cow and the Calf pasture, is what is cal

led the Blowing cave. It is in the side of a hill, is of about 100 feet diameter, and emits constantly a current of air, of such force, as to keep the weeds prostrate to the distance of twenty yards before it. This current is strongest in dry, frosty weather, and in long spells of rain weakest. Regular inspirations and expirations of air, by caverns and fissures, have been probably enough accounted for, by supposing them combined with intermitting fountains; as they must of course inhale air while their reservoirs are emptying theinselves, and again emit it while they are filling. But a constant issue of air, only varying in its force as the weather is drier or damper, will require a new hypothesis. There is another blowing cave in the Cumberland inountain, about a mile from where it crosses the Carolina line. All we know of this is, that it is not constant, and that a fountain of water issues from it.

The Natural Bridge, the most sublime of nature's works, though not comprehended under the present heail, must not be preterinitteil. It is on the ascent of a hill, which seems to have been rloven through its length by some great convulsion. The fissure, just at the bridge, is by some admeasurements, 270 feet deep, by others only 205. It is about 45 feet wide at the bottom, and 90 feet at the top: this of course determines the length of the bridge, and its height from the water, its breadth in the middle is about 60 feet, but more at the ends, and the thickness of the mass, at the sunmit of the arch, about 40 feet. A part of this thickness is constituted by a coat of earth, which gives growth to many large trees. The residue, with the hill on hoth sides, is one solid rock of lime-stone.—The arch approaches the semi-eliptical form; but the larger axis of the elipses, which would be the cord of the arch, is many tiines longer than the transverse. Though the sides of this bridye are provided in some parts with a parapet of fixed rocks, yei few men have resolution to walk to them, and look over into the abyss. You involuntarily fall on your hands and feet, creep to the parapet and peep over it. Looking down from this

height about a minute, gave me a violent head-ache. If the view from the top be painful and intolerable, that from below is delightful in an equal extreme. It is impossible for the emotions arising from the sublime, to be felt beyond what they are here : so beautiful an arch, so elevated, so light, and springing as it were up to heaven!

the rapture of the spectator is really indescribable! The fissure continuing narrow, deep and straight, for a considerable distance above and below the bridge, opens a short but very pleasing view of the North mountain on one side, and Blue Ridge on the other, at the distance each of them of about five miles. This bridge is in the County of Rockbridge, to which it has given name, and affords a public and commodious passage over a valley, which cannot be crossed elsewhere for a considerable distance. The stream passing under it is called Cedar-creek. It is a water of James' river, and sufficient in the driest seasons to turn a grist mill, though its fountain is not more than two miles above.*

Esta caxa,

* Don Ulloa mentions a break, similar to this, in the province of Angaraez, in South America. It is from 16 to 22 feet wide, 111 feet deep, and 1. 3 miles continuance, English measure. Its breadth at top is not sensibly greater than at bottom. But the following fact is remarkable, and will furnish some light for conjecturing the probable origin of our natural bridge. o cauce está cortada en péna viva con tanta precision, que las desigualdades del un lado entrantes corresponden a las del otro lado salientes, como si aquella altura se hubiese abierto expresamente, con sus bueltas y tortuosidades, para darle transito a los aguas por entre los dos murallones que la forman; siendo tal su igualdad, que si illegasen à juntarse se endentarian uno con otro sin dexar hueco.' Not. Amer. II. ( 10. Don Ulloa inclines to the opinion, that this channel has been effected by the wearing of the water which runs through it, rather than that the mountain should have been broken open by any convulsion of nature. But if it had been worn by the running of water, would not the rocks which form the sides, have been worn plain? or if, meeting in some parts with veins of harder stone, the water had left prominences on the one side, would not the same cause have sometimes, or perhaps generally, occasioned prominences on the other side also?" Yet Don Ulloa

QUERY VI.

A NOTICE of the mines and other subterraneous riches ; its trees, plants, fruits, &c ?

I knew a single instance of gold found in this state. It was interspersed in small specks through a lump of ore, of about four pounds weight, which yielded seventeen penny weight of gold, of extraordinary ductility. This ore was found on the north side of Rappahanoc, about four miles below the falls. I never heard of any other indication of gold in its neighbourhood.

On the great Kanhaway, opposite to the mouth of Cripple creek, and about twenty-five miles from our southern boundary, in the county of Montgomery, are mines of lead. The metal is mixed, sometimes with earth, and sometimes with rock, which requires the force of gunp

ler to open it; and is accompanied with a portion of silver, too small to be worth separation under any process hitherto attempted there. The proportion yielded is from 50 to 80lb. of pure metal from 100lb. of washed ore. The most common is that of 60 to the 100lb. The veins are at sometimes most flattering ; at others they disappear suddenly and totally. They enter the side of the hill, and proceed horizontally. Two of them are wrought at present by the public, the best of which is 100 tells us, that on the other side there are always corresponding cavities, and that these tally with the prominences so perfectly, that, were the two sides to come together, they would sit in all their indentures, without leaving any void. I think that this does not resemble the effect of running water, but looks rather as if the two sides had parted asunder. The sides of the break, over which is the natural bridge of Virginia, consisting of a veiny rock which yields to time, the correspondence between the salient and re-entering inequalities, if it existed at all, has now disappeared. This break has the advantage of the one described by Don Ulloa in its finest circumstance; no portion in that instance having held together, during the separation of the other parts, so as to form a bridge over the abyss.

The pre

yards under the hill. These would employ about 50 labourers to advantage. We have not, however, more than 30 generally, and these cultivate their own corp. They have produced 60 tons of lead in the year; but the general quantity is from 20 to 25 tons. sent furnace is a mile from the ore bauk, and on the opposite side of the river. The ore is first wagoned to the river, a quarter of a mile, ihen laden on board of canoes, and carried across the river, which is there about 200 yards wide, and then again taken into wagons and carried to the furnace. This mode was originally adopted, that they might avail themselves of a good situation on a creek, for a pounding mill: but it would be easy to have the furnace and pounding millon the same side of the river, which would yield water, without any dam, by a canal of about half a mile in length. From the furnace the lead is transported 130 miles along a good road, leading through the peaks of Otier to Lyncli's ferry, or Winston's on James' river, froin whence it is carried by water about the same distance to Westhamn. This land carriage may be greatly shortened, by delivering the lead

on James'

river, above the Blue ridge, from whence a tou weight has been brought ou two canoes. The great Kanhaway has considerable falls in the neighbourhood of the niines. About seven miles below are three falls, of three or four feet perpendicular each ; and three miles above is a rapid of three miles continuance, which has been compared in its descent to the great falls of Jaines' river. Yet it is the opinion, that they may be laid open for useful navigation, so as to reduce very much the portage between the Kanhaway and James' rivers.

A valuable lead mine is said to have been lately discovered in Cumberland, below the mouth of Red river. The greatest, however, known in the western country, are on the Mississippi, extending from the mouth of Rock river 150 miles upwards. These are not wrought, the lead used in that country being from the banks on the Spanish side of the Mississippi, opposite to Kaskaskia.

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