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 ...

198 THE STEAM ENGINE.
Whatever be the method adopted to surmount inclined
planes upon a railway, inconvenience attends the descent
upon them. The motion down the incline by the force of
gravity is accelerated; and if the train be not retarded, a
descent of any considerable length, even at a small elevation,
would produce a velocity which would be attended with
great danger. The shoe used to retard the descent down
hills on turnpike roads cannot be used upon railroads, and
the application of brakes to the faces of the wheels is likewise attended with some uncertainty. The fiiction produced
by the rapid motion of the wheel sometimes sets fire to wood,
and iron would be inadmissible. The action of the steam
on the piston may be reversed, so as to oppose the motion
of the wheels; but even this is attended with peculiar difficulty.
From all that has been stated, it will be apparent that,
with our present knowledge, considerable inclines are fatal
to the profitable performance on a railway, and even small
inclinations are attended with great inconvenience.'*
(97.) To obtain from the locomotive steam engines now
used on the railway the most powerful effects, it is necessary
that the load placed on each engine should be very considerable. It is not possible, with our present knowledge, to
construct and work three locomotive engines of this kind,
each drawing a load of 30 tons, at the same expense and with
the same effect as one locomotive engine drawing 90 tons.
Hence arises what must appear an inconvenience and difficulty in applying these engines to one of the most profitable
species of transport-the transport of passengers. It is impracticable, even between places of the most considerable
* A contrivance might be applied in changes of level in railroads somewhat
similar to locks in a canal. The train might be rolled upon a platform which
might be raised by machinery; and thus at the change of level there would be
as it were steps from one level to another, up which the loads would be lifted
by any power applied to work the machinery. The advantage in this case
would be, that the trains might be adapted to work always upon a level.