the Value of the Phot Constant. 



:57 



gasometer at the right velocity for the greater part of its 

 fall, and the required rate of this wns given by the average 

 distance between the seconds marks on the paper strip. 



Determination of Kj. — Having determined by the process 

 of trial and error the distribution of pitot pressure across a 

 diameter for a given mean rate of flow, the value of Kj at 

 that velocity can be determined from curves drawn with 

 \/P as ordinates and positions of the pitot along a radius as 

 abscissae, as mentioned above. Some examples of these are 

 given in Curves II for mean velocities 400, 120, and 50 cms. 



Curves II. 



2D ">n.T»v£ 



R>Stt£o">v of Pitot 



per second respectively, P being measured in centimetres of 

 water. The values for the ordinates of w = 120 and y=50 

 are doubled and trebled respectively for convenience in 

 plotting. 



The pitot in these cases was a circular metal tube of 

 radius 0*59 mm. The results verified the general form of 



