ving of capital outlay.
Inasmuch as the winding-engine, even when the ore haulage is finished
for the day, must be under steam for handling men in emergencies,
and as the labor of stokers, engine-drivers, shaft-men, etc., is
therefore necessary, the cost of power consumed by bailing is not
great, despite the low efficiency of winding-engines.

COMPARISON OF VARIOUS SYSTEMS.--If it is assumed that flexibility,
reliability, mechanical efficiency, and capital cost can each be
divided into four figures of relative importance,--_A_, _B_, _C_,
and _D_, with _A_ representing the most desirable result,--it is
possible to indicate roughly the comparative values of various
pumping systems. It is not pretended that the four degrees are of
equal import. In all cases the factor of general power conditions
on the mine may alter the relative positions.

====================================================================
|Direct|Compressed| |Steam-| |
|Steam | Air |Electricity|Driven|Hydraulic|Bailing
|Pumps | | | Rods | Columns | Tanks
-------------|------|----------|-----------|------|---------|-------
Flexibility. | _A_ | _A_ | _B_ | _D_ | _B_ | _A_
Reliability. | _B_ | _B_ | _B_ | _A_ | _D_ | _A_
Mechanical | | | | | |
Efficiency.| _C_ | _D_ | _B_ | _A_ | _C_ | _D_
Capital Cost | _A_ | _B_ | _B_ | _D_ | _D_ | --
====================================================================

As each mine has its special environment, it is impossible to formulate
any final conclusion on a subject so involved. The attempt would lead
to a discussion of a thousand supposititious cases and hypothetical
remedies. Further, the description alone of pumping machines would
fill volumes, and the subject will never be exhausted. The engineer
confronted with pumping problems must marshal all the alternatives,
count his money, and apply the tests of flexibility, reliability,
efficiency, and cost, choose the system of least disadvantages,
and finally deprecate the whole affair, for it is but a parasite
growth on the mine.

CHAPTER XIV.

Mechanical Equipment (_Concluded_).

MACHINE DRILLING: POWER TRANSMISSION; COMPRESSED AIR _VS_. ELECTRICITY;
AIR DRILLS; MACHINE _VS_. HAND DRILLING. WORK-SHOPS. IMPROVEMENT
IN EQUIPMENT.

For over two hundred years