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ders 26% inches and a stroke of 60 inches. Its
capacity in free air is about 4,400 cubic feet per
minute. The other compressor is at the Highland
shaft and is of the same type as that just described.
Its stroke is 42 inches, the air cylinders
are 22% inches and the steam cylinders 20 inches
in diameter. At the rated speed its free air
capacity is about 2,600 cubic feet per minute.
These two compressors, together with the giant
at the Ellison shaft, are operating over two
hundred Ingersoll-Sergeant rock drills in the mine
workings.
In the hoist room at the Ellison shaft, not far
from the largest compressor, is installed a small
Ingersoll-Sergeant Class "GC" compressor, with
duplex steam sylinders and a two-stage air end.
This is one of the smallest machines equipped
with the piston inlet valve and the contrast between
it and the large machine adjacent is striking.
The smaller machine has a stroke of 12
inches, its steam cylinders are 10 inches in diameter.
Its high pressure air cylinder is 10% inches
diameter and its low pressure 16% inches. At
the rated speed of 160 R. P. M. the piston displacement
is 444 cubic feet of free air per minute.
The air from this compressor is used in the cylinders
controlling the starting, stopping, reversing
and braking of the Ellison hoist. In this engine
room is located a straight-line high pressure compressor
of the same make furnishing air at 900
pounds pressure to charge the storage tanks of a
locomotive used in hauling ore cars between shafts
and mills in the surface workings.
For various purposes in the mills and surface
workings, two other air compressors of Ingersoll-
Sergeant make are installed. These are both
of the Corliss type, with piston inlet valves. The
sizes of these machines are 12 and 16% inches,
with 36 inch stroke, duplex type, and 12 and 18%.
inches by 36 inches, half duplex. Their combined
capacity in free air is about 2,100 cubic feet
of free air per minute.
The air compressor installation of the Homestake
mine, just described, is but one branch of
the elaborate system of labor-saving and costreducing
machinery which has made this the
greatest gold mine in the world. The policy of
the management has from the first been one of
broad-minded recognition of the value of small
economies. The best engineering skill has been
employed in the application of the highest class
of machinery to the various processes of mining
and milling. Not the cheapest machinery, but
the best and most economical, has always been
selected, the increased investment being always
justified by labor savings.
THE COAL TRADE BULLETIN.
TO REDUCE CONSUMPTION
AMONG BRITISH MINERS.
The council of the Institution of Mining and
Metallurgy has issued a memorandum to the members
of the institution calling attention to the
serious nature of the statistics of miner's phthisis,
urging the immediate adoption of effective
methods of prevention, and requesting the collection
of further information as to the prevalence of
the disease and the conditions which give rise to
it. The opinion is that the main cause of the
disease is the breathing of air containing dust.
The air in mines must, therefore, be kept free
from dust, if possible, and certainly work must
not be performed immediately after blasting, etc..
while dust is temporarily in the air. It is recommended
that in drilling, water should be used in
such a way that no dust shall escape into the air,
whether the hole be bored upward or downward;
that dust after blasting should be drowned by
water, removed by ventilation, or allowed to subside
before the men return, and that "broken
rock" should, if possible, be damped before removal.
The council is asking the co-operation of technical
societies in the collection of information on
the following points: Frequency or infrequency
of the disease in connection with different kinds
of mining work and different varieties of rock;
nature and amount of the dust present in the air
in different varieties of mining work; nature,
amount and effects on miners of the gaseous impurities
met with in the air of metalliferous
mines—in particular, poisonous impurities arising
from blasting, etc.; means in actual use for preventing
the formation and inhalation of dust or
poisonous gases; evidence as to efficacy and practicability,
or otherwise, of these means.
West Virginians make the claim that their state
has more different kinds of bituminous coal than
any other state in the union, or on this or any
other continent.
One-Way Settlers' Fares to South and Southeast.
One-way excursion tickets to points in Alabama,
Florida, Georgia, Kentucky, Louisiana, Mississippi,
North Carolina, South Carolina, Tennessee and
Virginia, account Settlers' Excursions, will be sold
from all ticket stations on the Pennsylvania Lines,
during December. January, February, March and
April. For full particulars consult J. K. Dillon,
District Passenger Agent, 515 Park Building, Pittsburgh,
Pa.