[Illustration: Fig. 20.--Details of Windmill Manufactured by Messrs. Duke and
Ockenden, Littlehampton.]

It will be seen that the strain on the crank shaft is taken by
a bent crank which disposes the load centrally on the casting,
and avoids an overhanging crank disc, which has been an
objectionable feature in some other types. The position of the
crank shaft relative to the rocker pin holes is studied to give
a slow upward motion to the rocker with a more rapid downward
stroke, the difference in speed being most marked in the
longest stroke, where it is most required.

In order to transmit the circular internal motion a vertical
connecting rod in compression is used, which permits of a
simple method of changing the length of stroke by merely
altering the pin in the rocking lever, the result being that
the pump rod travels in a vertical line.

The governing is entirely automatic. If the pressure on the
wind wheel, which it will be seen is set off the centre line of
the mill and tower, exceeds that found desirable--and this can
be regulated by means of a spring on the fantail--the windmill
automatically turns on the turn-table and presents an ellipse
to the wind instead of a circular face, thus decreasing the
area exposed to the wind gradually until the wheel reaches its
final position, or is hauled out of gear, when the edges only
are opposed to the full force of the wind. The whole weight of
the mill is taken upon a ball-bearing turn-table to facilitate
instant "hunting" of the mill to the wind to enable it to take