Weight of the Air.
Reading edition
Another experiment will still better make you appreciate the value of this factor: the weight of the air.
Put a piece of supple leather in which a ring is attached under the bottle; pump the air out of the latter and you will be astonished at the weight you may hang on this leather without dragging it off.
Should you not have at hand a glass receiver, a wooden reel may serve instead (see fig.). On one of its faces place a piece of strong cardboard, in the middle of which a hook has been fastened; when the rarefaction is made, rather heavy weights must be hooked on before the cardboard is detached from the face of the rest.