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EXPLANATION OF THE PLATES.
metallic surfaces be diminished, the quantity of cold water or the capacity of the air-
pump, or both, should be increased to produce the same effect.
“ Haying now described the five several apparatus the combination of which (within
proper proportions as hereinbefore described as regard the first three) constitute my
invention, I proceed again to define and explain the extent of my claims. I now
therefore state, I do not claim the exclusive use of any one of the five apparatus
herein described taken separately, some of them, if not all, having been used before,
nor indeed do I claim the use of any two of them, if unaccompanied bj" any or either
of the others, but I do claim as my invention the exclusive use of the threefold
combination of the sufficient quantity of metallic surfaces, the sufficient quantity of
cold water passing among them, and the sufficiently capacious air-pump as herein
before fully described, whether the said threefold combination be used alone or com
bined with the distilling apparatus and the steam saver, or either of them. I
also claim the exclusive right of combining the distilling apparatus and the steam
saving apparatus, or either of them, with the above mentioned threefold combination,
or even with the two first of them, videlicet, the metallic surfaces and cold water
passing among them, should a less air-pump be used. In witness whereof,” &c.
The advantages of Mr. Hall’s patent engines over injection engines will perhaps
be best understood by his comparative statement of them.
“COMPARISON BETWEEN INJECTION STEAM ENGINES AND SAMUEL HALL’S
PATENT STEAM ENGINES.
“ 1. Injection engines, when applied to
steam navigation, comprise of necessity
the barbarous practice of supplying dirty
salt water to the boilers.
2. In injection engines, the water in
the boilers may become saturated with
salt, in which case it will not boil under
225° of temperature.
3. In injection engines, in order to pre
vent the water from becoming saturated
with salt, a large quantity of boiling
water must be pumped out of the boilers,
or blown off, and replaced with cold water
The patent engines effect a supply of
the purest distilled water to the boilers,
by which they are always kept in a
perfectly clean state.
The patent engines having pure dis
tilled water in the boilers, it boils at 212°
or at 13° less temperature than salt water,
and of course requires less fuel to convert
it into steam.
The boilers of the patent engines never
require any blowing out, no matter how
long the engines are in uninterrupted
operation.