onfined to few levels, storage-bins are not required at every
station. Figures 15, 16, 17, and 18 illustrate various arrangements
of loading bins.

CROSSCUTS.--Crosscuts are for two purposes, for roadway connection
of levels to the shaft or to other levels, and for prospecting
purposes. The number of crosscuts for roadways can sometimes be
decreased by making the connections with the shaft at every second
or even every third level, thus not only saving in the construction
cost of crosscuts and stations, but also in the expenses of scattered
tramming. The matter becomes especially worth considering where
the quantity of ore that can thus be accumulated warrants mule
or mechanical haulage. This subject will be referred to later on.

[Illustration: Fig. 17.--Arrangement of loading chutes in vertical
shaft.]

On the second purpose of crosscuts,--that of prospecting,--one
observation merits emphasis. This is, that the tendency of ore-fissures
to be formed in parallels warrants more systematic crosscutting
into the country rock than is done in many mines.

[Illustration: Fig. 18.--Cross-section of station arrangement for
skip-haulage in inclined shaft.]

LEVELS.

The word "level" is another example of miners' adaptations in
nomenclature. Its use in the sense of tunnels driven in the direction
of the strike of the deposit has better, but less used, synonyms in
the words "drifts" or "drives." The term "level" is used by miners
in two senses, in that it is sometimes applied to all openings on one
horizon, crosscuts included. Levels are for three purposes,--for a
stoping base; for prospecting the deposit; and for roadways. As a
prospecting and a stoping base it is desirable that the level should
be driven on the deposit; as a roadway, that it should constitute
the shortest distance between two points and be in the soundest
ground. On narrow, erratic deposits the levels usually must serve
all three purposes at once; but in wider and more regular deposits
levels are often driven separately for roadways from the level
which forms the stoping base and prospecting datum.

There was a time when mines were worked by driving the level on ore
and enlarging it top and bottom as far as the ground would stand,
then driving the next level 15 to 20 feet below, and repeating the
operation. This interval gradually expanded, but for some reason
100 feet was for years assumed to be the proper distance between
levels. Scattered over every