Moreover, all the parts of the engine are self-contained; they no
longer depend upon the foundation, and in many cases the condensing is
effected either by surface condensers, or, where there is not
sufficient water, the condensation is, in a few instances, effected by
the evaporative condenser--a condenser which, I am sorry to say, is
not generally known, and is therefore but seldom used, although its
existence has been nearly as long as that of the association.
Notwithstanding the length of time during which the evaporative
condenser has been known to some engineers, it is a common thing to
hear persons say, when you ask them if they are using a condensing
engine, "I can not use it; I have not water enough." A very sufficient
answer indeed, if an injection condenser or an ordinary surface
condenser constituted the sole means by which a vacuous condition
might be obtained; but a very insufficient answer, having regard to
the existence of the evaporative condenser, as by its means, whenever
there is water enough for the feed of a non condensing engine, there
is enough to condense, and to produce a good vacuum.
The evaporative condenser simply consists of a series of pipes, in
which is the steam to be condensed, and over which the water is
allowed to fall in a continuous rain. By this arrangement there is
evaporated from the outside of the condenser a weight of water which
goes away in a cloud of vapor, and is nearly equal to that which is
condensed, and is returned as feed into the boiler. The same water is
pumped up and used outside the condenser, over and over, needing no
more to supply the waste than would be needed as feed water. Although
this condenser has, as I have said, been in use for thirty or forty
years, one still sees engines working without condensation at all, or
with waterworks water, purchased at a great cost, and to the detriment
of other consumers who want it for ordinary domestic purposes; or one
sees large condensing ponds made, in which the injection water is
stored to be used over and over again, and frequently (especially
toward the end of the week) in so tepid a state as to be unfit for its
purpose. The governing is now done by means of quick-running
governors, which have power enough in them to raise not merely the
weight of the pendulum ball, which is now small, but a very heavy
weight, and in this way the governing is extremely effective. I
propose to say no more, looking at the magnitude of the whole of my
subject, upon the engine used for manufacturing purposes, but rather
to turn at once to those employed for other objects.