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 ...

200 THE STEAMI ENGINE.
be for a line connecting Birmingham with Liverpool or
London.
The establishments of resident engineers, coach and wagon
yards, &c. at the extremities of the line, would be little increased by a very great increase in the length of the railway;
and the same observation will apply to other heads of expenditure.
It has been the practice of the canal companies between
Liverpool and Manchester to warehouse the goods transported between these towns, without any additional charge
beyond the price of transport. The Railway Company, in
competing with the canals, were, of course, obliged to offer
like advantages: this compelled them to invest a considerable amount of capital in the building of extensive warehouses, and to incur the annual expense of porterage, salaries, &c. connected with the maintenance of such storage.
In a longer line of railway such expenses (if necessary at all)
would not be proportionally increased.
(99.) The comparison of steam-transport with the transport by horses, even when working on a railway, exhibits
the advantage of this new power in a most striking point of
view. To comprehend these advantages fully, it will be
necessary to consider the manner in which animal power is
expended as a means of transport. The portion of the
strength of a horse available for the purpose of a load depends
on the speed of a horse's motion. To this speed there is
a certain limit, at which the whole power of the horse will
be necessary to move his own body, and at which, therefore,
he is incapable of carrying any load; and, on the other hand,
there is a certain load which the horse is barely able to suppolt, but incapable of moving with anry useful speed. Between these two limits there is a certain rate of motion at
which the useful effect of the animal is greatest. In horses
of the heavier class, this rate of motion may be taken on the
average as that of 2 miles an hdur; and in the lighter description of horses, 2- miles an hour. Beyond this speed,