APPENDIX. 



TABLE XII. 



It thus appears contrary to the results of all experiments hitherto made on the small scale, 

 that the resistance of a well-shaped vessel does not exceed -j^th part that of a plane of the 

 same sectional area. 



The above mean, being founded on several experiments, must be very near the truth ; 

 although in each so much error may exist, from the want of minute attention to the number 

 of strokes of the engine, as to afford no test of the best shaped vessel. 



As, however, the results are very extraordinary, it may be well to submit them to a totally 

 independent mode of estimation. In the above investigation, the mean number of acting 

 paddles, with their corresponding velocities and areas, are compared with the sectional area of 

 the vessel and its velocity ; but we might have made the calculation in another way, that is, 

 by comparing the force necessary to urge a plane section equal to that of the vessel with the 

 velocity at which it passes through the water, with the actual power of the engine employed 

 to propel the vessel, which ought to give nearly the same fraction as the other method. 



Of the whole power of the engine, we have seen that with the vertically acting paddle one- 

 third is lost by the retrograding of the wheel : in the Medea, therefore, the power employed 

 in propelling the vessel is two-thirds of 220 = 146 horse power: now the velocity of the 

 vessel having been 11-33 English miles per hour, or 16-62 feet per second, the resistance in 



feet of water is 



and in Ibs. rrr. x 62J, on each square foot. The number of 



64i (341 



feet in the section is 263, and the velocity in feet per minute is 997 ; the whole force, there- 

 fore, expended in a minute, is 70,796,970, which, divided by 33,000, gives 2150 horse power 

 for the force necessary to urge a plane section of 263 feet through the water at the rate of 

 1 1-33 miles per hour : but the vessel itself is urged with that velocity by the power of 146 

 horses ; the resistance to a vessel is therefore to that of a plane section of the same area as 



