t into another shape, just as the
contents of a hogshead of porter are the same, whether they be let off by
an inch tap or by a hole a foot in diameter. There is a greater gush in the
one case than the other, but it will last a shorter time; when a lever is
used there is a greater force exerted, but it acts through a shorter
distance. It requires just the same expenditure of mechanical power to lift
1 lb. through 100 ft., as to lift 100 lbs. through 1 foot. A cylinder of a
given cubical capacity will exert the same power by each stroke, whether
the cylinder be made tall and narrow, or short and wide; but in the one
case it will raise a small weight through a great height, and in the other
case, a great weight through a small height.

47. _Q._--Is there no loss of power by the use of the crank?

_A._--Not any. Many persons have supposed that there was a loss of power by
the use of the crank, because at the top and bottom centres it is capable
of exerting little or no power; but at those times there is little or no
steam consumed, so that no waste of power is occasioned by the peculiarity.
Those who imagine that there is a loss of power caused by the crank perplex
themselves by confounding the vertical with the circumferential velocity.
If the circle of the crank be divided by any number of equidistant
horizontal lines, it will be obvious that there must be the same steam
consumed, and the same power expended, when the crank pin passes from the
level of one line to the level of the other, in whatever part of the circle
it may be, those lines being indicative of equal ascents or descents of the
piston. But it will be seen that the circumferential velocity is greater
with the same expenditure of steam when the crank pin approaches the top
and bottom centres; and this increased velocity exactly compensates for the
diminished leverage, so that there is the same power given out by the crank
in each of the divisions.

48. _Q._--Have no plans been projected for gaining power by means of a
lever?

_A._--Yes, many plans,--some of them displaying much ingenuity, but all
displaying a complete ignorance of the first principles of mechanics, which
teach that power cannot be gained by any multiplication of levers and
wheels. I have occasionally heard persons say: "You gain a great deal of
power by the use of a capstan; why not apply the same resource in the case
of a steam vessel, and increase the power of your engine by placing a
c