med; although this is the principal element of its cost. We
must consider that the attainment and maintenance of high speed depend
upon the exertion of a high power; and that,

I. High speed and power require stronger parts in every thing: in the
ship's build, the machinery, the boilers, and all of the working
arrangements:

II. High speed and power require a larger outlay in prime cost, in
material and building, for the adequate resistance required by such
power:

III. High speed and power require more frequent and costly repairs:

IV. High speed and power require more watchfulness, a more prompt
action, and consequently more persons:

V. High speed and power require more fuel, more engineers, more
firemen, and more coal-stokers.

1. These propositions are nearly all self-evident to every class of
mind. That a high speed attained through the exertion of a high power
will require stronger parts in every thing that exerts a force or
resists one, is as manifest as that a force necessary to remove one
ton of weight will have to be doubled to remove two tons. In the prime
construction of the hull this is as requisite as in any other part.
The resistance to a vessel, or the concussion against the water, at a
low rate of speed, will not be very sensibly felt; but if that speed
is considerably increased and the concussion made quicker without a
corresponding increase in the strength of the frame and hull of the
ship generally, we shall find the ship creaking, straining, and
yielding to the pressure, until finally it works itself to pieces, and
also disconcerts the engines, whose stability, bracing, and keeping
proper place and working order depend first and essentially on the
permanence and stability of the hull. If the resistance to a vessel in
passing through the water increases as the square of the velocity, and
if in addition to this outward thrust against the vessel it has to
support the greater engine power within it, which has increased as the
cube of the velocity, then the strength of the vessel must be adequate
to resist without injury these two combined forces against which it
has to contend.

The same increased strength is necessary also in the engines and
boilers. It is admitted by the ablest engineers, and verified by
practice, as will be shown in another part of this Section, that to
increase the speed of a steamer from eight to ten knots per hour, it
is necessary to double the power, and so on in the ra