Nipher — On Pressure Measurements in a Fluid Stream. 21 

 The radial acceleration of dm towards the center is 



a = a)V. 



Then 



Hence 



dP = aBdr = a>V j(b-^P) dr. 





dr 



or 



,2^2 



wr 



^±^_,20T (1) 



The mass m of air in the column of length r is 



Jr 8' /» r 



Bdr = -l- 1 (6 + P)(7r 

 Jo 



Combining this equation with (1) by the elimination of P, 

 we have for any constant angular velocity, 



b-\-F' r 



L 



r con 



,2^.2 



e 2CTrf, <2> 



In this equation the integral in the denominator was de- 

 termined by planimeter measurements between limits r = 

 and r = 100 cm, this outer limit being taken as the value of r 

 in the numerator. The temperature T was assumed' 293. 

 The number of rotations per second was assumed n = 10, in 



(i)2 —6 



which case aprp = 2.339 X 10 . 



The integration was repeated with values r = 50 cm. and 

 n = 20. 



