s, gasoline (petrol) motors
have more of a position in experimental than in systematic mining,
for their application to winding and pumping and drilling is fraught
with many losses. The engine must be under constant motion, and
that, too, with variable loads. Where power from producer gas is
used, there is a greater possibility of installing large equipments,
and it is generally applied to the winding and lesser units by
conversion into compressed air or electricity as an intermediate
stage.

One thing becomes certain from these examples cited, that the right
installation for any particular portion of the mine's equipment cannot
be determined without reference to all the others. The whole system
of power generation for surface work, as well as the transmission
underground, must be formulated with regard to furnishing the best
total result from all the complicated primary and secondary motors,
even at the sacrifice of some members.

Each mine is a unique problem, and while it would be easy to sketch
an ideal plant, there is no mine within the writer's knowledge
upon which the ideal would, under the many variable conditions,
be the most economical of installation or the most efficient of
operation. The dominant feature of the task is an endeavor to find
a compromise between efficiency and capital outlay. The result is
a series of choices between unsatisfying alternatives, a number of
which are usually found to have been wrong upon further extension
of the mine in depth.

In a general way, it may be stated that where power is generated
on the mine, economy in labor of handling fuel, driving engines,
generation and condensing steam where steam is used, demand a
consolidated power plant for the whole mine equipment. The principal
motors should be driven direct by steam or gas, with power distribution
by electricity to all outlying surface motors and sometimes to
underground motors, and also to some underground motors by compressed
air.

Much progress has been made in the past few years in the perfection
of larger mining tools. Inherently many of our devices are of a
wasteful character, not only on account of the need of special
forms of transmission, but because they are required to operate
under greatly varying loads. As an outcome of transmission losses
and of providing capacity to cope with heavy peak loads, their
efficiency on the basis of actual foot-pounds of work accomplished
is very low.

The adoption of ele