the air through the blow-hole and the conduit into the shaft. Although
this machine has no need of men whom it is necessary to pay to work the
crank, still when the sky is devoid of wind, as it often is, the machine does
not turn, and it is therefore less suitable than the others for ventilating a shaft.
In the kind where the fans are fixed to an axle, there is generally a
hollow stationary drum at one end of the axle, and on the other end is fixed
a drum made of rundles. This rundle drum is turned by the toothed wheel
of a lower axle, which is itself turned by a wheel whose buckets receive the
impetus of water. If the locality supplies an abundance of water this
machine is most useful, because to turn the crank does not need men
who require pay, and because it forces air without cessation through the
conduit into the shaft.
