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EXPLANATION OF THE PLATES.
internal parts of the engines, whereby
they are rendered untrue, and a consider
able quantity of steam escapes past them
and is wasted.
8. In injection engines, salt water, dirt,
sand, and other impurities pass through
the air pumps and thereby render them
and their piston rods, &c., very rough and
full of furrows; in consequence whereof,
great friction in working them and waste
of power is occasioned.
9. In injection engines, a considerable
power is required to pump out the injec
tion water; in engines of 450 horse power,
(like those on board the Great Western,)
2700 gallons of water per minute have to
be pumped out of a vacuum, (reckoning
six gallons per horse power per minute,)
and this requires as much power as the
pumping of that quantity of water out of
a well 30 or 32 feet deep.
10. In injection engines, in stormy wea
ther and heavy seas the condensing water
enters the condensers as rapidly when the
engines are going at a slow as when they
are going at a fast speed, and as it is impos
sible to regulate the quantity of injection
water according to the irregularity of the
speed of the engines, great danger arises
on the one hand of choking the condenser
and the air pump, and of even breaking
down the engines, by the admission of
too much water when they are going
slow, or on the other hand, of deducting
greatly from the power of the engines by
cles into the cylinder, thus, this ample
lubrication actually improves the slides,
valves, and other internal parts of the en
gines instead of injuring them, whereby
a great saving in their wear and tear is
effected.
In the patent engines, nothing but dis
tilled water and oil pass through the
air pumps, which instead of becoming
rough are thereby rendered more smooth
and polished, and of course brass buckets,
piston rods, and linings to the ah pumps
are not necessary, as is the case in injec
tion engines.
In the patent engines, the air pump has
only to pump out of the vacuum, the wa
ter resulting from the condensation of the
steam, which in a pair of engines of 450
horse power is only about 50 gallons per
minute; the saving of the power, there
fore, required to pump out the 2700 gal
lons per minute of injection water is so
much additional effective power gained
and applicable to the paddle wheels.
The patent engines, in the roughest
weather and when the greatest power is
required, preserve as perfect a vacuum, and
consequently as great a power, as in fine
weather, and all the power required in
injection engines to supply the proper
quantity of condensing water is super
seded, and the engineer is relieved from
that onerous duty.