He further demonstrated that in a vacuum all bodies fall equally fast, that animals cannot exist therein, or, in fact, living matter. He is also credited with being the inventor of the air balance and a type of weather cock, called the anemoscope. He was interested also in astronomy.
Fig. 7
EXPERIMENT NO. 4
This experiment should interest you very much, because it is going to lead up to the subject of weather instruments, and is absolutely essential that you understand the fundamental principles in order to intelligently interpret these instruments. This experiment will explain one of the principles of the barometer.
Take a glass tube thirty-two inches long and one-quarter or one-eighth inch in diameter, and fill it with mercury, care being used to get rid of all the air bubbles. The mercury should be poured in with an eye dropper, one end of the tube being sealed, until filled, and then the finger is placed over the open end. (See Fig. [7A]). The tube is inverted and immersed in a reservoir of mercury and clamped to an upright stand. Immediately the mercury falls to about thirty inches. (See Fig. [7B]). Ask yourself what held the mercury up in the tube. Again the answer is that the pressure of the air on the mercury in the reservoir causes it to rise and fall in the tube, as the pressure of the air changes. You will soon learn what causes these changes in the pressure of the air.
Fig. 8
EXPERIMENT NO. 5
Have you ever asked yourself why it is that the wind blows? Why doesn’t it stand still?