So that a vacuum may be produced in it.
How is this accomplished?
By means of two valves in the pump-tree.
What is a valve like?
A valve is like the lid on a tea-kettle, or the cover on an inkstand; and it is kept in its place by a hinge on one side.
Where is one valve placed?
One valve is placed in the lower part of the pump-tube.
How near the water must this valve be?
It must be within thirty-four feet of the water.
Why must the lower valve be within thirty-four feet of the water in the well?