The pressure of the air upon the leather keeps it against the stone.
With how much force does the air press the leather against the stone?
With a force of fifteen pounds on every square inch.
When there is air between the stone and the leather, can the stone be lifted with the sucker?
It cannot; because the air under the leather will press it up as much as the air above will press it down.
How does a fly walk upon the ceiling?
The fly’s feet are much like the sucker, and are kept against the ceiling by the pressure of the air.
How do snails cling to objects?
They force out all the air between the object and their bodies, and are then held against the object, as the sucker is held against the stone.
What is a siphon?