The Diving-Bell. The oldest information we have respecting the use of the diving-bell in Europe is that of John Taisnier, quoted by Schott. The former, who was born at Hainault in 1509, had a place at court under Charles V., whom he attended on his voyage to Africa. He relates in what manner he saw at Toledo, in the presence of the emperor and several thousand spectators, two Greeks let them-Selves down under water, in a large inverted kettle, with a burning light, and rise up again without being wet. It appears that this art was then new to the emperor and the Spaniards, and that the Greeks were induced to make the experiment in order to prove the possibility of it. The principle of the diving-bell depends upon the impenetrability of atmospheric air, and may be explained by a very familiar experiment. Bring the edge of an inverted tumbler, or any dose vessel, to the surface of water, and, keeping the mouth horizontal, press it down in the water. It will be seen that though some portion of the water ascends into the tumbler, the greater part of the space remains empty, or only filled with air ; and any object placed in this space, though surrounded on all sides with water, would remain perfectly dry. In fact, the quantity of air remains the same, but it is compressed into a smaller volume, in proportion to the depth to which it is made to descend.

The Diving Bell 277