of Fluids, compared with the best Experiments. '257 



of the resisting forces, which will vary in proportion to the 

 facility with which the fluid can escape by reflection from the 

 different parts of the surface. 



25. The experiments made by the Society for the Improve- 

 ment of Naval Architecture*, differ considerably from others, 

 but they are most readily compared in a tabular form. The 

 resistances were taken at a velocity of five nautical miles per 

 hour, which is equivalent to 8*35 feet per second. 



Form of the Body. 



Thin square plane 



Cube 



Thin round plane 



Cylinder 



Cylinder and hemispherical end 



The same reversed 



Cylinder terminating in a he-1 



misphere at both ends J 



Sphere 



Resistance 

 by Experi- 

 ment. 



Pounds. 

 80-76 

 79-34. 

 80-64 

 74*69 

 56-04 

 22-28 



18-53 



25-24 



Ration 



1-08 

 1-07 

 1-08 

 1-00 

 •75 

 •30 



•25 



•34 



Calculated 

 Resistance. 



Pounds. 

 100-7 

 100-7 

 100-7 

 100-7 

 83-9 

 60-4 



43-6 



43-6 



I have no doubt that there is an error somewhere in the 

 mode of trial which gave the resistance stated in the account 

 of these experiments, for they do not agree with others. 



26. Col. Beaufoy made some experiments on the resistance 

 of water, which appear to have been conducted in a similar 

 manner. He found the resistance of a square foot, moving at 

 the rate of one foot per second, to be 1 -2949 pound ; according 

 to my mode of calculation, it should be 1-45 pound. 



27. Borda, from an experiment made in sea-water, makes 

 the resistance of a foot of surface If pound Fr., at a velocity 

 of about one foot per second; and Bouguer, as quoted by 

 Robison, makes the resistance 1-44 pound Fr. My mode of 

 calculation gives 1*785 pound Fr. for the resistance of sea- 

 water, to a surface one foot square moving at the rate of one 

 foot (French) per second. 



28. Mr. Bevan has given me an account of some trials he 

 made to ascertain the resistance of a canal boat on the Grand 

 Junction Canal. The length of the boat was 69*57 feet; its 

 width, 6-83 feet ; floating depth in the water, 0*89 foot ; weight, 

 9 1 tons ; radius of curvature four times the breadth ; and the 

 area of surface in contact with the water, 540 feet. (See fig. 7.) 



* Buchanan on Propelling Vessels by Steam. 1816. 

 New Series. Vol. 3. No. 16. April 1828. 2 L The 



