Air may escape from the pollywog when it
is turning a somersault; if so, water will take its place, and may
make the pollywog too heavy to float. You can restore its buoyancy
by sucking out the water.
FIG. 28
DRAWING GLASS SPIDER-WEBS
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Experiment 14. A dancing pollywog.
Make a pollywog as in Experiment 12, but
bend its tail twice as shown in 1, Fig. 27; the
nozzle is at one side and points sidewise.
Put it in the bottle full of water, then
press down and release the stopper.
FIG. 29
THE SPIDER TRICK
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Does it sink and rise, and does it also whirl around most beautifully
as it rises?
Make another pollywog (2,
Fig. 27), but bend its nozzle in the opposite
direction. Does it whirl in a direction opposite to that of the first
pollywog?
Put them in the bottle together and treat
your friends to a pollywog dance.
The pollywog whirls because the water
rushes out of the nozzle in one direction and forces the nozzle
in the opposite direction.
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