Scientific American Supplement, No. 312, December 24, 1881 | Page 5

arms, thus being, as will be readily seen, very inefficient

regulators. The connection of the parts of the engine between
themselves was derived from the foundation upon which the engine
was supported. Incident to the low piston speed was slowness of
revolution, rendering necessary heavy fly wheels, to obtain even an
approach to practical uniformity of rotation, and frequently rendering
necessary also heavy trains of toothed gearing, to bring up the speed
from that of the revolutions of the engine to that of the machinery it
was intended to drive.
In 1881, the boilers are almost invariably cylindrical, and are very
commonly internally fired, either by one flue or by two; we owe it to
the late Sir William Fairbairn, President of the British Association in
1861, that the danger, which at one time existed, of the collapse of
these fire flues, has been entirely removed by his application of
circumferential bands. Nowadays there are, as we know, modifications
of Sir William Fairbairn's bands, but by means of his bands, or by
modifications thereof, all internally flued boilers are so strengthened
that the risk of a collapse of the flue is at an end. Boilers of this kind
are well calculated to furnish--and commonly do furnish--steam of
from 40 lb. to 80 lb. pressure above atmosphere.
The piston speed is now very generally 400 feet or more, so that,
notwithstanding that there is usually a liberal expansion, the mean
pressure upon the piston is increased, and this, coupled with its
increased speed, enables much more power to be obtained from a given
size of cylinder than was formerly obtainable. The revolutions of the
engine now are as many as from 60 to 200 per minute, and thus, with
far lighter fly-wheels, uniformity of rotation is much more nearly
attained.
THE EVAPORATIVE CONDENSER.
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.
STEAM NAVIGATION.

In 1831, there were a considerable number of paddle steamers running
along some of the rivers in England, and across the Channel to the
Continent. But there were no ocean steamers, properly so-called, and
there were no steamers used