While making a tour through the various chambers, I found a pair of doves, which had been placed there for testing the effect of the compressed air. The birds appeared to have become accustomed to their new habitation, where they had been for several weeks. They looked, however, rather disconsolate and sickly, and I learned, a day or two later, that one had died from the effects of its imprisonment. A black and tan terrier had also been taken into the caisson, but after it had been down a few hours it became paralyzed in its hind legs, and was taken up; and for more than a fortnight it did not recover from the shock to its system. [Sidenote: SCENES IN THE CAISSON.] The scene in the caisson is a very novel one. The water, seen through the gas jets, sparkles in the pools at the bottom of the river, the men are toiling and perspiring amid the rushing and rumbling noise of the sand siphons, and everything appears in confusion. While our party was making its tour, it was found that our voices had completely changed; each one appeared to stutter, and altogether the voice had a very unnatural sound, as if we spoke in a half screeching key. An attempt was made to whistle, but whistle we could not. The lips might be puckered, and you might blow as hard as you pleased, but it was all in vain, as not a note could be heard. Some of us tried to whistle by our fingers, but were unsuccessful. Communication is had with the upper-world by means of a movable iron rod and a couple of dials, one above and the other below. These form the telegraph. On each dial are printed, in plain letters, the words, “All right,” “Start,” “Faster,” “Slower,” “Stop,” “Less,” “More,” “Bucket is caught,” “Highest corner,” “Stopped,” “Come up all;” and the last is the most pleasing call of the entire number to the laborers below. Adjoining the dial is a thermometer, which indicated the atmosphere to be eighty-two degrees Fahrenheit. Accidents occur in the caisson, in spite of all precautions. A short time before my visit, a small stone caught in the pipe of the siphon, and one of the workmen came very near losing his arm while attempting to pull it out. His hand was drawn into the pipe, as if by a powerful magnet. The man was thrown upon his face by the great power of the atmosphere, and at the same time his arm was drawn up the pipe: had it not been for four of his comrades instantly pulling his arm down, the limb would have been torn from his shoulder. He received severe injuries, and is not likely to be so careless again. The skin of the arm looked as if a quantity of boiling oil had been poured over it, and it soon became blistered from his shoulder downward. After a stay of nearly an hour, the party proceeded to return once more to terra firma. We entered the lock, as on making the descent, through the small iron door; then the compressed air was allowed to escape until the pressure of the air was equal to that of the atmosphere outside.