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MINING IN CALIFORNIA AND NEVADA.
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an underlay shaft, deserves mentioning:—a a represents the exhaust pipe of a steam engine, 4 inches diameter, and b b the suction pipe from the bottom of the shaft, 700 feet deep; these two pipes were joined together
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at c, leaving in a an open orifice for b. The exhaust steam would pass by this orifice, create a vacuum, and thus induce suction at the lowest end of pipe b in the shaft. .
Section III.
BOILERS.
These
steam generators in California and Nevada belong exclusively to the
tubular kind, or what is termed the " return tubular ;" and, after
close observation, I came, like Mr. Bland, of the Port Phillip Company,
Clunes, to the conclusion of their superiority over the single or
double-tubed Cornish boiler, but that those used by the Clunes Company
were surpassed by those of California for the following reasons, some
of which are, however, applicable to both kinds of boilers, viz.:—The
heat as produced by the combustion of fuel is distributed throughout
the water more perfectly and generally, on account of the greater
heating surfaces presented to the burning fuel and gases. They also
require less length for the same capacity, and also cost not so much in
California as Cornish boilers of equal horse-power. For instance, a
boiler, 42 inches diameter, 12 feet long, with 32 4-inch tubes, "
steam-drum" on top, 5 feet long, 2 feet diameter, "mud drum" at bottom,
7 feet long, 18 inches diameter, fire front lined with firebricks,
smoke stack, fire bars, steam gauges, blow-off cocks, safety-valve,
complete, and made of the best materials, costs only 900 dollars;
whereas a Cornish boiler would at least cost 30 per cent, more in that
State. The difficulties attending the cleaning and the repair of the
tubes are considerably overrated with these kinds of boilers ; with
proper care, such a boiler, as specified, will last six years or more,
and about four years longer if repaired occasionally. A tubular boiler
will also effect a saving of at least 20 per cent, in fuel alone, on
account of the better circulation of the water in the boiler through
the interference of the tubes, and the latter add considerably to the
steaming power of such boilers. This in itself should be a question of
grave importance in districts where fuel is becoming more and more
scarce and dearer every day.
Generally speaking, the Californian return tubular boilers are worked in couples, i.e., each pair is connected, top and bottom, by means of the "steam" drum and "mud" dram. The first named has been adopted in
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