more useful than the first one for drawing water out of shafts, into which
much water is continually flowing. This machine has no iron frame nor
drums, but has around its axle a wooden wheel which is turned by treading;
the axle, since it has no drum, does not last very long. In other respects
this pump resembles the first kind, except that it differs from it by having
a double chain. Clamps should be fixed to the axle of this machine, just as
to the drum of the other one ; some of these are made simple and others
with triple curves, but each kind has four barbs.
The third machine, which far excels the two just described, is made
when a running stream can be diverted to a mine; the impetus of the
stream striking the paddles revolves a water-wheel in place of the wheel
turned by treading. With regard to the axle, it is like the second machine,
