At a given signal, we began our journey into the East River, and descended until we reached what our conductor termed the “lock.” Here we changed our stands again, and entered the lock by crawling through an opening at the bottom of the elevator sufficiently large for a man of ordinary size to pass easily. This lock is an oblong iron box, or boiler, of just sufficient size to allow half a dozen persons to stand erect. It is eight feet long, and six feet in diameter. At the bottom of the lock there is an iron door or opening, similar to that through which we entered, which gives admission to the interior of the caisson. These iron doors are fitted with rubber, so as to make them perfectly air-tight. When we had all entered, the door was closed upon us. We looked at each other, wondering what would be done next, and we soon found out. Our conductor, previous to starting the lock, gave us what he termed a few useful hints, so that we might be able to make the trip as agreeable as possible under all the circumstances. “Now, gentlemen,” said he, “in descending, you will find a disagreeable sensation, particularly about your ears. You will find great ease by closing the nostrils every few seconds,—as the pressure of the air will act upon the tympanum of the ear,—and also by inflating your cheeks to their full extent.” These instructions were given that we might cause an artificial pressure upon the inside of the ear, and thus prevent its rupture. Our conductor then proceeded to turn a cock, to admit the air forced from above. In a moment it rushed in with a tremendous force, making a noise similar to that of a locomotive blowing off steam. The effect of this was anything but pleasant. A sudden deafness seemed to overtake us, as if a cannon had been fired under our noses; our voices were also changed, and appeared cracked, and we almost wished our curiosity had not led us so far. [Sidenote: A HEAVY PRESSURE OF AIR.] This feeling was caused by the air rushing too fast into the orifice of the ear. There was just sufficient light inside the lock to discern our faces, and that was all. It took five or six minutes to get the necessary amount of pressure into the lock, and then the air was turned off. We seemed suddenly to lose our footing, and then to regain it; and no sooner had we righted ourselves than we had another sudden shoot, and this continued until we reached the bottom. The actual descent was made in about a minute and a half, or perhaps two minutes; but owing to the pain we suffered, it appeared to be three times as long.