e the wheel revolve, but it could be thrown down at
any time to stop it.

THE PUMP.

[Illustration: Fig. 290. Side View of the Wind Wheel, showing Brake.]

Our pump was made of a galvanized leader pipe; that is, a pipe used to
carry off rain water from the roof of the house. The pipe was only about
8 feet long, and so we had to piece it out with a long wooden box pipe.
A block closed the lower end of this box, and the leader pipe fitted
snugly into a hole in the block (Fig. 291). A spout was set into the
upper end of the box pipe to carry the water to the cask, which was to
serve as our water reservoir.

THE PUMP VALVES.

[Illustration: Fig. 291. The Box Pipe.]

[Illustration: Fig. 292. The Lower Valve.]

[Illustration: Fig. 293. The Piston Valve.]

We plugged the bottom of the leader pipe with a block of wood, in the
center of which a large hole was drilled. The hole was covered with a
piece of leather nailed at one side, so that it could lift up to let
water into the pipe. The piston was made of a disk of wood of slightly
smaller diameter than the inside of the pipe, and over it was fastened a
piece of leather just large enough to fit snugly against the walls of
the pipe. This piston was fastened to a wooden rod long enough to reach
from well within the pipe to the wind wheel shaft. A strip of brass was
bent over the crank, or U-shaped bend in the shaft, and its ends were
fastened to the rod.

[Illustration: The Old Windmill at Work on a Lumberville Farm.]

ACTION OF THE PUMP.

[Illustration: Fig. 294. Connection of Rod and Crank.]

It was rather a crude pump, but it did all the work we required of it.
As the wheel went around the crank shaft would move the piston up and
down. Whenever the piston went down, the air in the pipe would press up
the edges of the leather disk and squeeze past (see Fig. 295). Then when
the piston came up again, the leather disk, being backed by the wooden
disk beneath it, was kept flat, so that no air could force its way back
into the pipe. This made a partial vacuum in the pipe, and the water
from the well rushed up through the valve at the bottom to fill it (see
Fig. 296). When next the piston went down the bottom valve closed and
more air forced its way past the piston. Then on the next upward stroke
more water flowed into the pipe, until, after a number of strokes, all
the air was pumped out and the water which took its place began to force
its way up past the pisto