THE MOTION OF STEAM VESSELS. 329 



It thus appears, contrary to the results of all experiments hitherto made upon a 

 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, I have no doubt is 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 calcu- 

 lation in another way, that is, by comparing the force necessary to urge a plane sec- 

 tion 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 powers. 

 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 q^i~ and in pounds q^i X 62 J 



on each square foot. The number of feet in the section is 263, and the velocity in 

 feet per minute is 997- The whole force therefore expended in a minute is 70796970, 

 which divided by 33000 gives 2150 horse power for the force necessary to urge a plane 

 section of 263 feet through the water at the rate of 11*33 miles per hour. But the 

 vessel itself is urged with that velocity by the power of 146 horses. The resistance 

 of a vessel is therefore to that of a plane section of the same area as 146 to 2150, or 

 as 1 to 1 5 very nearly, which agrees exactly with the number given in the Table. 

 The agreement is equally close in the Flamer ; and I find the mean obtained this way 

 from the whole set of experiments, is very nearly the same as that given in the above 

 Table. 



Since this Paper was read at the Royal Society, Henry Beaufoy, Esq. has, with a 

 noble generosity, presented to his scientific countrymen one of the most valuable col- 

 lections of resistances ever published, made by his father, the late celebrated Colonel 

 Beaufoy ; and it is very satisfactory to be able to confirm the above extraordinary 

 results on the authority of his tables. 



I have found above that to urge a plane section of 263 feet area at the rate of 1 1*33 

 English miles, or 9*84 nautical miles per hour through still water, would require 2150 

 horse powers. According to Colonel Beaufoy's results it would require a power of 



