Nipher — On Pressure Measurements in a Fluid Stream. 23 



A series of similar integrations was then made for a tube 

 of length r= 100 cm., for various speeds n. In the follow- 

 ing table the pressure at the axis of rotation in terms of the 

 pressure b throughout the tube when n = 0, is given in 

 column 3. In the fourth column the pressure at the outer 

 end where r=100, is given. These values are computed 

 from those in column (3) by means of equation (1). 



After some experimenting, it was found that the values in 

 column 3 may be represented fairly well by the following 

 empirical equation 



b + r 



b 



1 + e«»' 



av2 



(3) 



Where a is a constant quantity, to be hereafter discussed, 

 and V = ft) 7", the velocity of the outer end of the tube. 



