Although the sides of the bridge are provided in some parts with a parapet of fixed rocks, yet few persons have resolution to walk to them, and look over into the abyss. The passenger involuntarily falls on his hands, creeps to the parapet, and peeps over it. Looking down from this height for the space of a minute, occasions a violent headache; and the view from beneath is delightful in the extreme, as much as that from above is exquisitely painful. The following beautiful sketch is from the pen of the Rev. John Todd, of Philadelphia, author of the Student's Manual, Simple Sketches, and other admired works. ROCK BRIDGE. On a lovely morning towards the close of spring, I found myself in a very beautiful part of the great valley of Virginia. Spurred on by impatience, I beheld the sun rising in splendour, and changing the blue tints on the tops of the lofty Alleghany mountains into streaks of purest gold; and nature seemed to smile in the freshness of beauty. A ride of about fifteen miles, and a pleasant woodland ramble of about two, brought myself and my companion to the great NATURAL BRIDGE. Although I had been anxiously looking forward to this time, and my mind had been considerably excited by expectation, yet I was not altogether prepared for this visit. This great work of nature is considered by many as the second great curiosity in our country, Niagara Falls being the first. I do not expect to convey a very correct idea of this bridge; for no description can do this.