Manchester Memoirs, Vol. Iviii. (19 14), No. 1. 15 



of " dead water " will be about the centre of the disc and 

 on either side of it, and will be bounded by a surface of 

 discontinuity. 



On that side of the disc which faces the current, the 

 pressure of the still fluid is given by the formula : 



and may be measured by a manometer in connection with 

 the small tube d. 



Fig. 5. 

 On the opposite side of the disc the pressure is lower 

 than this in the ratio of i : 0'37. This has been tested at 

 many velocities, and the ratio proved to be constant. 

 Thus when the two tubes of the Pneumometer c and d are 

 connected to the two ends of a manometer respectively, the 

 pressure which the latter reads is : 



