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The Cartesian Diver "consists of a glass cylinder nearly
full of water, on the top of which a brass cap, provided with a piston,
is hermetically fitted. In the liquid there is a little porcelain figure
attached to a hollow glass ball a, which contains air and water,
and floats on the surface. In the lower part of this ball there is a little
hole by which water can enter or escape, according as the air in the interior
is more of less compressed. The quantity of water in the globe is such
that very little more is required, to make it sink. If the piston is slightly
lowered, the air is compressed, and this pressure is transmitted to the
water of the vessel, and the air in the bulb. The consequence is, that
a small quantity of water penetrates into the bulb, which therefore becomes
heavier and sinks. If the pressure is relieved, the air in the bulb expands,
expels the excess of water which had entered it, and the apparatus being
now lighter, rises to the surface. The experiment may also be made, by
replacing the brass cap and piston by a cover of sheet india rubber, which
is tightly tied over the mouth: when this is pressed by the hand the same
effects are produced." Quote and cut from Ganot's Physics (William
Wood and Co., New York, 1875), pg 89.
This example is in the Garland Collection of Classical Physics Apparatus at Vanderbilt University. It is 59 cm tall. |
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