SCIENTIFIC PUZZLES.
Reading edition
Fig. 1.
Fig. 2.
Here are two very simple experiments that will not fail to excite a good deal of interest and wonderment among persons who are unfamiliar with them.
The first illustrates the pressure of the atmosphere. Take a coin and rub it against some oaken book-case or very smooth wooden surface, as shown in Fig. 1. Press it hard for a moment, and then withdraw the fingers. The coin will continue to stick to the wood.
The reason of this is that the rubbing and the pressure have dispersed the air which was between the coin and the wood, and the pressure of the atmosphere is sufficient to keep the coin in its place.
To perform the experiment shown in Fig. 2 fill a glass carefully with water up to the brim, so that the surface of the water is rounded. Then ask the by-standers how many coins can be thrown into the glass without the water over-flowing. Some will emphatically declare that it will not hold one; others will admit that there may possibly be room for one or two.
By dropping the coins very carefully into the water edge-ways, it will be found that even as many as five or six coins the size of a silver dollar can be dropped into the water before it overflows.