eath the steam cylinder; and there are two
fly-wheels, one on each end of said shaft, the crank-pins being fast in
the hubs of the same. There are two connecting rods, which are attached
one to each end of an end beam pin 28 inches in diameter. The main center
and crank shafts are also 28 inches in diameter; each of the two plunger
holes is 24 inches by 30 inches in section; and all the working parts are
in proportion to those heretofore mentioned.

Perhaps no mining district has ever had to contend against greater
difficulties in pumping than have faced the engineers of the celebrated
Comstock lode, Virginia City, Nev. The mines are of great depth, in some
instances 3,300 feet; and the water is hot, rising to 160 degrees Fahr.
The machinery collected at this location is of great variety and
magnitude. There are many Davey engines, both horizontal and vertical.
The Union and Yellow Jacket shafts have compound fly wheel engines of
very great power; the former having a beam, and the latter being
horizontal, with cylinders placed side by side, and pistons connected to
a massive cross-head, from the ends of which connecting rods lead to
crank pins located in the hubs of the fly-wheels, which are overhung upon
the ends of the main shaft. From the center of the cross head, a link
runs to the main pump-bob, which operates a double line of 16 inch pumps,
10 foot stroke. The steam stroke is 12 feet. Depth of shaft, 3,300 feet.

The pumping machinery used in the iron and copper districts of Michigan
usually consists of Cornish plunger pumps, which are operated by geared
engines; the latter making from three to sixteen strokes to one of the
pumps.

The largest plant of this type yet erected is that of the Calumet and
Hecla copper mine, at Calumet, Mich. There are two lines of pumps,
varying in diameter from 7 inches to 14 inches, and with an adjustable
stroke varying from 3 feet to 9 feet. The object of the adjustable stroke
is to diminish the capacity of the pumps in the dry season. Each line of
pumps is driven from a crank placed on a steel spur-wheel shaft 15 inches
in diameter, making ten revolutions per minute. The mortise spur-wheels
have a diameter of 221/2 feet at the pitch line, with two rows of teeth,
each 15 inches face. The pitch is 4.72 inches. Engaging with the mortise
wheels are pinions of gun iron 4 feet 6 inches in diameter, placed on
steel shafts 12 inches in diameter, and making 50 revolutions per minute.
The