eing now largely displaced by the use of the tail-rope.

The first and third of these are absolutely essential for anything
like economy and speed; the others are refinements depending on
the work to be accomplished and the capital available.

Steam winding-engines require large cylinders to start the load,
but when once started the requisite power is much reduced and the
load is too small for steam economy. The throttling of the engine
for controlling speed and reversing the engine at periodic stoppages
militates against the maximum expansion and condensation of the
steam and further increases the steam consumption. In result, the
best of direct compound condensing engines consume from 60 to 100
pounds of steam per horse-power hour, against a possible efficiency
of such an engine working under constant load of less than 16 pounds
of steam per horse-power hour.

It is only within very recent years that electrical motors have
been applied to winding. Even yet, all things considered, this
application is of doubtful value except in localities of extremely
cheap electrical power. The constant speed of alternating current
motors at once places them at a disadvantage for this work of high
peak and intermittent loads. While continuous-current motors can
be made to partially overcome this drawback, such a current, where
power is purchased or transmitted a long distance, is available
only by conversion, which further increases the losses. However,
schemes of electrical winding are in course of development which
bid fair, by a sort of storage of power in heavy fly-wheels or
storage batteries after the peak load, to reduce the total power
consumption; but the very high first cost so far prevents their
very general adoption for metal mining.

Winding-engines driven by direct water- or gas-power are of too rare
application to warrant much discussion. Gasoline driven hoists have a
distinct place in prospecting and early-stage mining, especially in
desert countries where transport and fuel conditions are onerous,
for both the machines and their fuel are easy of transport. As direct
gas-engines entail constant motion of the engine at the power demand
of the peak load, they are hopeless in mechanical efficiency.

Like all other motors in mining, the size and arrangement of the
motor and drum are dependent upon the duty which they will be called
upon to perform. This is primarily dependent upon the depth to be
hoisted from, the vol