260 Mr. Tredgold on a new Theory of the Resistance 



show how far the formula will apply to great variation of ve- 

 locity. 



The equation for a spherical ball reduced to the form ap- 

 plicable to this case is 



£0< 



3 + 



1*3 x 0-000000332 x 4 v 



)=H; 



and since a cubic foot of air weighs 1*2 ounce at the mean 

 temperature and pressure, and the area of the section of the 

 ball is d? x -7854 feet, it becomes 



i)^ 1 /. , 0-000001328 v \ . 



— (1 + -. ) = the resistance in ounces. 



In this series of comparisons there are only two places in 

 which the difference amounts to y 1 ^ ; and the one is in excess, the 

 other in defect ; and if the resistances were represented by the 



ordinates 



