FIG. 102
TUMBLER PENDULUM
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atmospheric pressure upward and downward holds your hand and the tumbler
together.
Experiment 78. A magic pendulum.
Pass a string through a small hole in a piece of
cardboard, knot the end of the string, and drop melted candle wax over
the hole to make it air tight.
Fill a tumbler with water, press the cardboard
down on the tumbler with the palm of your hand, and lift the string. Do
you also lift the tumbler (Fig. 102)?
Swing the tumbler gently as a pendulum.
Experiment 79. A poultry fountain.
FIG. 103
POULTRY FOUNTAIN
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To make the poultry fountain (Fig. 103), fill
a bottle with water, hold your thumb over the mouth, invert the bottle
over the pan of water, and remove your thumb under water. Does the
atmospheric pressure on the water in the pan hold the water in the
bottle?
Lift the bottle until the mouth is a little
above the water in the pan. Does air
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