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.[2] FOOTNOTE: [2] Don Ulloa mentions a break, similar to this, in the province of Angaraez, in South America. It is from sixteen to twenty-two feet wide, one hundred and eleven feet deep, and of 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. "Esta caxa, ó cauce está cortada en péna viva con tanta precision, que las desigualdades del un lado entrantes, corresponden á las del otro lado salientes, como si aquella altura se hubiese abierto expresamente, con sus bueltas y tortuosidades, para darle transito á los aguas por entre los dos morallones que la forman; siendo tal su igualdad, que si llegasen á juntarse se endentarian uno con otro sin dextar 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 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 fit 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. QUERY VI.