A.—­Experiments have been made both to determine the relative resistance of different classes of vessels, and also the absolute resistance in pounds or tons.  The first experiments made upon this subject were conducted by Messrs. Boulton and Watt, and they have been numerous, long continued, and carefully performed.  These experiments were made upon paddle vessels.

543. Q.—­Will you recount the chief results of these experiments?

A.—­The purpose of the experiments was to establish a coefficient of performance, which with any given class of vessel would enable the speed, which would be obtained with any given power, to be readily predicted.  This coefficient was obtained by multiplying the cube of the velocity of the vessels experimented upon, in miles per hour, by the sectional area of the immersed midship section in square feet, and dividing by the numbers of nominal horses power, and this coefficient will be large in the proportion of the goodness of the shape of the vessel.

544. Q.—­How many experiments were made altogether?

A.—­There were five different sets of experiments on five different classes of vessels.  The first set of experiments was made in 1828, upon the vessels Caledonia, Diana, Eclipse, Kingshead, Moordyke, and Eagle-vessels of a similar form and all with square bilges and flat floors; and the result was to establish the number 925 as the coefficient of performance of such vessels.  The second set of experiments was made upon the superior vessels Venus, Swiftsure, Dasher, Arrow, Spitfire, Fury, Albion, Queen, Dart, Hawk, Margaret, and Hero-all vessels having flat floors and round bilges, where the coefficient became 1160.  The third set of experiments was made upon the vessels Lightning, Meteor, James Watt, Cinderella, Navy Meteor, Crocodile, Watersprite, 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.