minute, with steam of 45 to 50 lbs. per square inch,
with two hydraulic presses having 13 inch rams of
41 feet stroke, and force pumps 2 inches diameter
and 6 inches stroke, presses 30 bales of cotton per
hour. One condensing engine with cylinder 56
inches diameter, 10 feet stroke, and making 15 strokes
per minute with steam of 60 lbs. pressure per square
inch, cut off at 1/4th of the stroke, supplied by six
boilers, each 5 feet diameter, and 24 feet long, with
a 22-inch double-return flue in each, and 198 square
feet of fire grate, works a blast cylinder of 126 inches
diameter, and 10 feet stroke, at 15 strokes per minute.
The pressure of the blast is 4 to 5 lbs. per square
inch; the area of pipes 2300 square inches, and the
engine blows four furnaces of 14 feet diameter, each
making 100 tons of pig iron per week. Two high
pressure cylinders, each of 6 inches diameter and
18 inches stroke, making 60 to 80 strokes per minute,
with steam of 60 Lbs. per square inch, lift two rams,
each weighing 1000 lbs., five times in a minute, the
leaders for the lift being 24 feet long. One
high pressure cylinder of 12 inches diameter and 5
feet stroke, making 20 strokes per minute, with steam
of 60 to 70 lbs. pressure per square inch, lifts 6
buckets full of dredging per minute from a depth of
30 feet below the water, or lifts 10 buckets full
of mud per minute from a depth of 18 feet below the
water.

**MANUFACTURE AND MANAGEMENT OF STEAM ENGINES.**

700. *Q.*—What are the qualities which
should be possessed by the iron of which the cylinder
of steam engines are made?

*A.*—The general ambition in making
cylinders is to make them sound and hard; but it is
expedient also to make them tough, so as to approach
as nearly as possible to the state of malleable iron.
This may be done by mixing in the furnace as many
different kinds of iron as possible; and it may be
set down as a general rule in iron founding, that the
greater the number of the kinds of metal entering
into the composition of any casting, the denser and
tougher it will be. The constituent atoms of the
different kinds of iron appear to be of different
sizes, and the mixture of different kinds maintains
the toughness, while it adds to the density and cohesive
power. Hot blast iron was at one time generally
believed to be weaker than cold blast iron, but it
is now questioned whether it is not the stronger of
the two. The cohesive strength of unmixed iron
is not in proportion to its specific gravity, and
its elasticity and power to resist shocks appear to
become greater as the specific gravity becomes less.
Nos. 3 and 4 are the strongest irons. In most
cases, iron melted in a cupola is not so strong as
when remelted in an air furnace, and when run into
green sand it is not reckoned so strong as when run