THE SWIMMING NEEDLES

There are several ways of making a needle float on the surface of the

water.

The simplest way is to place a piece of tissue paper on the water and

lay the needle on it; the paper soon becomes soaked with water and

sinks to the bottom, while the needle is left floating on the top.

Another method is to hang the needle in two slings made of threads,

which must be carefully drawn away as soon as the needle floats.

You can also make the needle float by simply holding it in your

fingers and laying it on the water. This, however, requires a very

steady hand.

If you magnetize a sewing-needle by rubbing it on a fairly strong

magnet and float it on the water, it will make an extremely sensitive

compass; and if you place two needles on the water at the same time,

you will see them slowly approach each other until they float side by

side, that is, if they do not strike together so heavily as to cause

them to sink.

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My Book of Indoor Games · 第 164 / 187 题