es. In wide stopes with machine-drills they
vary from 7 to 10 feet; in narrow stopes with hand-holes, from
two to three feet.

[Illustration: Fig. 20.]

The position of the men in relation to the working face gives rise
to the usual primary classification of the methods of stoping.
They are:--

1. Underhand stopes,
2. Overhand stopes,
3. Combined stopes.

These terms originated from the direction of the drill-holes, but
this is no longer a logical basis of distinction, for underhand
holes in overhand stopes,--as in rill-stoping,--are used entirely
in some mines (Fig. 21).

[Illustration: Fig. 21.]

UNDERHAND STOPES.--Underhand stopes are those in which the ore
is broken downward from the levels. Inasmuch as this method has
the advantage of allowing the miner to strike his blows downward
and to stand upon the ore when at work, it was almost universal
before the invention of powder; and was applied more generally
before the invention of machine-drills than since. It is never
rightly introduced unless the stope is worked back from winzes
through which the ore broken can be let down to the level below,
as shown in Figures 22 and 23.

[Illustration: Fig. 22.]

This system can be advantageously applied only in the rare cases
in which the walls require little or no support, and where very
little or no waste requiring separation is broken with the ore
in the stopes. To support the walls in bad ground in underhand
stopes would be far more costly than with overhand stopes, for
square-set timbering would be most difficult to introduce, and
to support the walls with waste and stulls would be even more
troublesome. Any waste broken must needs be thrown up to the level
above or be stored upon specially built stages--again a costly
proceeding.

A further drawback lies in the fact that the broken ore follows
down the face of the stope, and must be shoveled off each bench.
It thus all arrives at a single point,--the winze,--and must be
drawn from a single ore-pass into the level. This usually results
not only in more shoveling but in a congestion at the passes not
present in overhand stoping, for with that method several chutes
are available for discharging ore into the levels. Where the walls
require no support and no selection is desired in the stopes, the
advantage of the men standing on the solid ore to work, and of
having all down holes and therefore drilled wet, gives this method
a distinct place. In using t