"That is provided for," said Captain Johnson, "by giving the diver a pair of shoes with soles of lead. They are so heavy that when he is out of water he can lift his feet with difficulty; but when he goes below, the specific gravity of the water makes them much lighter. He can then step around, and at the same time his equilibrium is maintained."
"How long can a man stay under water with the apparatus you have described?" Fred asked.
DIVERS AT WORK.
"From one to two hours," was the reply; "according to the depth and condition of the water. If it is very cold, he will be chilled in a little while, and must come up to get warm again; and if he has to hold himself against a strong current he will find his strength leaving him, and must make a signal to be drawn to the surface. I have been two hours under, at a depth of eighty feet, and felt no inconvenience; but when I came up I was not able to go down again for several hours."
"Can you go down in the open sea in this way," said Fred, "or must you always be where the water is quiet?"
DIVING OVER THE SIDE OF A STEAMER.