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 120, actual 234; Firefly, nominal 52, actual 86.6; Ferret, nominal 52, actual 88; Monarch, nominal 200, actual 378.  In the case of swift vessels of modern construction, such as the Red Rover, Herne, Queen, and Prince of Wales, the coefficient appears to be about 2550; but in these vessels there is a still greater excess of the actual over the nominal power than in the case of the vessels previously enumerated, and the increase in the coefficient is consequent upon the increased pressure of the steam in the boiler, as well as the superior form of the ship.  The nominal power of the Red Rover, Herne, and City of Canterbury is, in each case, 120 horses, but the actual power of the Red Rover is 294, of the Herne 354, and of the City of Canterbury 306, and in some vessels the excess is still greater; so that with such variations it becomes necessary to adopt a coefficient derived from the introduction of the actual instead of the nominal power.

547. Q.—­What will be the average difference between the nominal and actual powers in the several classes of vessels you have mentioned and the respective coefficients when corrected for the actual power?

A.—­In the first class of vessels experimented upon, the actual power was about 1.6 times greater than the nominal power; in the second class, 1.67 times greater; in the third class, 1.7 times greater; and in the fourth, 1.96 times greater; while in such vessels as the Red Rover and City of Canterbury, it is 2.65 times greater; so that if we adopt the actual instead of the nominal power in fixing the coefficients, we shall have 554 as the first