e, Thetis, Dolphin, Wizard, Escape, and
Dragon-all vessels with rising floors and round bilges, and the coefficient
of performance was found to be 1430. The fourth set of experiments was made
in 1834, upon the vessels Magnet, Dart, Eclipse, Flamer, Firefly, Ferret,
and Monarch, when the coefficient of performance was found to be 1580. The
fifth set of experiments was made upon the Red Rover, City of Canterbury,
Herne, Queen, and Prince of Wales, and in the case of those vessels the
coefficient rose to 2550. The velocity of any of these vessels, with any
power or sectional area, may be ascertained by multiplying the coefficient
of its class by the nominal horse power, dividing by the sectional area in
square feet, and extracting the cube root of the quotient, which will be
the velocity in miles per hour; or the number of nominal horse power
requisite for the accomplishment of any required speed may be ascertained
by multiplying the cube of the required velocity in miles per hour, by the
sectional area in square feet, and dividing by the coefficient: the
quotient is the number of nominal horse power requisite to realize the
speed.

545. _Q._--Seeing, however, that the nominal power does not represent an
invariable amount of dynamical efficiency, would it not be better to make
the comparison with reference to the actual power?

_A._--In the whole of the experiments recited, except in the case of one or
two of the last, the pressure of steam in the boiler varied between 2-3/4
lbs. and 4 lbs. per square inch, and the effective pressure on the piston
varied between 11 lbs. and 13 lbs. per square inch, so that the average
ratio of the nominal to the actual power may be easily computed; but it
will be preferable to state the nominal power of some of the vessels, and
their actual power as ascertained by experiment.

546. _Q._--Then state this.

_A._--Of the Eclipse, the nominal power was 76, and the actual power 144.4
horses; of the Arrow, the nominal power was 60, and the actual 119.5;
Spitfire, nominal 40, actual 64; Fury, nominal 40, actual 65.6; Albion,
nominal 80, actual 135.4; Dart, nominal 100, actual 152.4; Hawk, nominal
40, actual 73; Hero, nominal 100, actual 171.4; Meteor, nominal 100, actual
160; James Watt, nominal 120, actual 204; Watersprite, nominal 76, actual
157.6; Dolphin, nominal 140, actual 238; Dragon, nominal 80, actual 131;
Magnet, nominal 140, actual 238; Dart, nominal 120, actual 237; Flamer,
nominal