The steam engine familiarly explained and illustrated; with an historical sketch of its invention and progressive improvement; its applications to navigation and railways; with plain maxims for railway speculators. By the Rev. Dionysius Lardner ... With additions and notes by James Renwick ...

LOCOMOTIVE ENGINES ON RAILWAYS. 197
being raised to the temperature of the water with which it
mixes, it must absorb a considerable portion of the heat
supplied by the fire. With a view to accelerate the production of steam, therefore, in ascending the inclines, the engine-man may suspend the action of the forcing pump, and
thereby stop the supply of cold water to the boiler; the
evaporation will go on with increased rapidity, and the exhaustion of water produced by it will be repaid by the
forcing pump on the next level, or still more effectually on
the next descending incline. Indeed, the feeding pump may
be made to act in descending an incline if necessary, when
the action of the engine itself is suspended, and when the
train descends by its own gravity, in which case it will perform the part of a brake upon the descending train.
This method, on railroads intended for passengers, may be
successfully applied on inclines which do not exceed 18
feet in a mile; and, with a sacrifice of the expense of locomotive power, inclines so steep as 36 feet in a mile may be
worked in this manner. As, however, the sacrifice is considerable, it will, perhaps, be always better to work the more
steep inclines by assistant engines.
5. The mechanical connexion between the piston of the
cylinder and the points of contact of the working wheels
with the road may be so altered, upon arriving at the incline,
as to give the piston a greater power over the working
wheels. This may be done in an infinite variety of ways,
but hitherto no method has been suggested sufficiently simple to be applicable in practice; and even were any means
suggested which would accomplish this, unless the intensity
of the impelling power were at the same time increased, it
would necessarily follow that the speed of the motion would
be diminished in exactly the same proportion as the power
of the piston over the working wheels would be increased.
Thus, on the inclined plane, which rises 55 feet per mile,
upon the Liverpool line, the speed would be diminished to
nearly one-fourth of its amount upon the level.
R 2