This instrument consists of a glass tube in the bottom of whose there is a faucet made of brass which is connected to a vacuum pump. At the top of the tube we place a piece of wood, after we cut it perpendicularly to the direction of its fibers. Then, we aplly the piece of wood to a funnel which contains mercury. When the tube is full of air, the mercury cannnot descend into the tube through the timber. When we remove the air with a vacuum pump, the mercury can easily pass through the holes in the wood and fall into the glass tube. So, it seems like silver rain. Alternatively, a piece of skin can be used instead of wood. Later, the former instrument was used as an experimental arrangement in order to demonstrate the free fall phenomenon, in which when two objects release from the same height at the same time, they fall to the ground at the same time, since the only thing that matters is the power of gravity. (Air resistance is negligible.) As far as the freefall experiment is concerned we can use, for instance, a piece of paper and a small metal ball.
Identifier: MP 275.1