When, with my friend's aid, I had donned this curious-looking dress, he placed across my shoulders ropes sustaining two leaden weights, one hanging at my breast and the other at my back. Sometimes in very strong currents it is necessary to make the weights which the diver carries extraordinarily heavy. Such was the case with those hanging over my shoulders on the occasion of my first dive. While the diving dress I wore weighed of itself nearly two hundred pounds, yet, much to my surprise, when once below the surface, I did not find the burden I sustained in wearing it any more than I did that of my ordinary clothing when out of the water. It also seemed marvelous to me, after daylight had swiftly merged into the twilight of the depths, that though I was several fathoms under water my breathing was free and unconstrained, for an air-pump worked by two men supplies the diver with air, which passes into his helmet through a hose at the back. Near the place of its entrance is a spring valve for its escape. This can be controlled by the diver, but he usually sets it before going into the water and seldom disturbs it afterward, since the pressure of the air being greater than that of the water a surplus of the former readily escapes. When the valve proves insufficient to permit the escape of all the dead air the diver can open in his breast-plate a similar spring valve intended only for such an emergency. He can also regulate the amount of air pumped to him by signals on the air-hose to the men engaged in pumping, one pull meaning more and two pulls less air. These signals by means of the air-hose are generally used by all divers, but each diver has also his own private code of signals upon the life-line, which is always fastened to his waist, and by which he is drawn up out of the water. These signals each diver writes down very carefully and gives to the man in charge of the life-line. By means of these he can, without coming to the surface, send for tools, material or anything needed for the work he has in hand. When a lengthy communication is to be made the diver often sends up for a slate and writes what he wishes to say. Old divers declare that it is just as easy to read and write under the water as it is out of it, all objects being greatly magnified.