FIG. 29
THE SPIDER TRICK
Put it in the bottle full of water, then press down and release the stopper. 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.
Experiment 15. To make glass spider-web.
Heat the end of a piece of No. 2 tube in the blowpipe flame until it is melted and very hot. Now touch the end of another piece of glass to the melted glass, remove from the flame, and quickly pull the two pieces apart as far as you can (Fig. 28). Do you find that you have pulled part of the melted glass out into a very fine glass spider-web?
Repeat, but ask a friend to touch the second piece of glass to the first and run away as fast as he can.
Do you get a much finer spider-web?
Is the glass spider-web fairly strong and very flexible?