Page:Popular Science Monthly Volume 38.djvu/231

Rh resistance to his progress. He sees things two steps away that he wants to get, and can not reach them.

Pictures show the diver walking along on the bottom of the sea as he would do on the land; it is a false representation. One can not get along without bending his whole body at an angle of forty-five degrees in the direction he wishes to go, and then pushing along on tip-toe in an attitude that would excite laughter in a beholder, assisting himself with his arms as in swimming. If the bottom is uneven, he will do better to creep on his hands and knees.

On the other hand, one can do things in the water that are impossible in the air—let himself drop, for example, from the rocks; the water will break the fall. Or, he can climb cliffs by letting a little air collect in his coat and planting the ends of his fingers in the cracks and rough places. On broken ground he can pass with a kind of flying leap from one rock to another. But all this supposes a degree of familiarity which is not acquired for a considerable time. In my first efforts I cut my hands terribly, and was not able to use my pen or pencil for several days. I tried a coat made with the sleeves ending in India-rubber gloves, but they prevented my picking up small things, and, moreover, did not last long. I then returned to the common sleeves, closed at the wrist, and used knit woolen gloves.

Another difficulty is occasioned by the glasses of the casque becoming covered with the vapor that results from the condensation of the moisture of the breath. The colder the water, the thicker the vapor is. No means as yet tried to get rid of it have resulted satisfactorily, but I have solved the problem by rubbing the glasses with glycerin. The mist then condenses in a uniform nap which does not obscure the glass.

When all these difficulties have been surmounted, there is still one that persists—that is, the effect and the danger of compression and decompression. That imposes a limit to the depth a man can reach with the diving-dress. Divers are liable to two kinds of accidents. One is a prostration on coming to the surface, for which restorative measures often have to be applied; and which, according to Paul Bert, results from the effects of the change of medium on the spinal marrow. It is rarely mortal, but may eventually produce a paralysis of the lower limbs. The other accident, graver but very rare, consists of a gaseous embolism of the capillaries of the lung, produced by the disengagement of bubbles of air in the blood, which has dissolved too much of it while under high pressure. The action is like that of Seltzer water at the moment of pressing on the pedal of the siphon. Under its effects, when it occurs, the diver dies as soon as he reaches the surface.