416 Natural Bridge in Virginia, 



tance each of them about five miles. This bridge is in the 

 county of Roclibridge, to which it has given name, and affords a 

 pubhc and commodious passage over a valley, v^hich cannot be 

 crossed elsewhere for a considerable distance. The stream pass- 

 ing 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."* 



COMPARATIVE VIEW OF THE LINN^AN' AND NATURAL 

 SYSTEMS OF BOTANY. 



The republication in this country, of Lindley's Introduction 

 to the Natural System of Botany, with an Appendix by Dr. 



* 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 of 13 miles con- 

 tinuance, 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, 6 cauce esta 

 cortada en pena viva con tanta precision, que las deflgualdades del un lado entran- 

 tes, 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 muralloncs que la forman ; siendo tal su igualdad, que si Ilcgasen k 

 juntarse se endcntarian 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 plane 1 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 1 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. Thia 

 break has the advantage of the one described by Don Ulloa in its finest circum- 

 stance ; no portion in that Instance having held together, during the separation of 

 the other parts, so as to form a bridge over the abyss. 



* This chasm is formed in the solid rock with so much precision, that the cavities on 

 one side, correspond with the protuberances on thoother, asif the dilT had opened asunder 

 for the express purpose of permitting the water to pass between its walls : tlie correspond- 

 ence being so exact, that if the walla could 1)0 brought together again, they would fit 

 exactly. 



