rusher and amalgamator where the material
to be operated on is comparatively soft, but does not do such good work
when the stone is of a hard flinty nature.

A No. 4 Dodge stone-breaker working about 8 hours will keep a five-foot
Huntingdon mill going 24 hours, and an automatic feeder is essential.
For that matter both are almost essential for an ordinary stamper
battery, and will certainly increase the crushing capacity and do better
work from the greater regularity of the feed.

A 10 h.-p. (nominal) engine of good type is sufficient for Huntingdon
mill, rock breaker, self-feeder and steam pump. A five-foot mill under
favourable circumstances will crush about as much as eight head of
medium weight stamps.

The Grusonwek Ball Mills, made by Krupp of Germany, also that made by
the Austral Otis Company, Melbourne, are fast and excellent crushing
triturating appliances for either wet or dry working, but are specially
suited only for ores when the gold is fine and evenly distributed in
the stone. The trituration is effected by revolving the stone in a large
cylinder together with a number of steel balls of various sizes, the
attrition of which with the rock quickly grinds it to powder of any
required degree of fineness.

More mines have been ruined by bad mill management probably than by bad
mining, though every experienced man must have seen in his time many
most flagrant instances of bungling in the latter respect. Shafts are
often sunk on the wrong side of the lode or too near or too far away
therefrom, while instances have not been wanting where the (mis) manager
has, after sinking his shaft, driven in the opposite direction to that
where the lode should be found.

A common error is that of erecting machinery before there is sufficient
ore in sight to make it certain that enough can be provided to keep the
plant going. In mines at a distance from the centre of direction it is
almost impossible to check mistakes of this description, caused by the
ignorance or over sanguineness of the mine superintendent, and they are
often as disastrous as they are indefensible. Another fertile source of
failure is the craze for experimenting with untried inventions, alleged
to be improvements on well-known methods.

A rule in the most scientific of card games, whist, is "when in doubt
lead trumps." It might be paraphrased for mining thus: "When in doubt
about machinery use that which has been proved." Let some one else do
the exp