_The Bliss-Heath Atmospheric Pumping Engine_ represented by Fig. 455
is novel in its construction, consisting of a low-pressure, upright,
tubular steam boiler, having a safety valve loaded to carry 1-1/2 lbs.
steam pressure. The large cover lifts under 2 lbs. pressure, hence
explosions cannot occur.
[Illustration: FIG. 455.]
NOTE.—The safety valve is shown on the floor alongside of the hand
bar arranged to work the feed pump. Fig. 455.
The motor is a simple atmospheric engine operating a plunger pump and a
single acting air pump.
The operation of this motor is almost noiseless.
The motive power is the normal pressure of the atmosphere (14.7 lbs. to
the square inch), utilized by the formation of a vacuum in the power
cylinder.
The air is expelled from the cylinder by admitting steam without
appreciable pressure, _i.e._, to balance that of the atmosphere,
after which the steam exhausts into the surface condenser, in which a
constant vacuum is maintained. Steam is then admitted automatically
into the power cylinder, breaking the vacuum and imparting to the
piston the required impetus. _This principle is identical with that of
the ordinary condensing steam engine_, with the exception of the very
low steam pressure in this connection.
[Illustration: FIG. 456.]
This engine can be operated satisfactorily in combination with an
ordinary house-heating boiler (low pressure), hence the expense of
running it is very low during the steam-heating season. During the
summer months the boiler connected with this engine can be used
advantageously.
The bearings are self-oiling, and the cylinder condensation furnishes
ample protection for the inside of the engine cylinder. There are no
leather packings to burn out, and this is remarkably free from the
objections to the older types of caloric engines.
These pumps when required will force a proportionate quantity of water
to a greater height than fifty feet, upon which the following table is
based: