184 



HYDKAULICS AND ITS APPLICATIONS 



Experimental Results. 



The main results of the experiments are given in the table opposite : 

 In this the values of n were obtained from curves representing logarithms 

 of the resisting moments in foot Ibs., plotted as ordinates against 

 logarithms of the revolutions per minute. Speeds varying between 450 

 and 2,200 revolutions per minute were used for the determinations. 



From these results it is apparent that in no case does n attain a value 



30' 40 



BO" 90 100 110' 120' 

 Temperature Degrees Fahr. 

 FIG. 94. Variation of Disc Resistance with Temperature. 



160' 



so high as 2, its maximum value, even with a rough cast-iron disc, being 

 only 1*915. A comparison of these results with those of Dr. Unwin 

 shows that in every case the values of n obtained by the latter experi- 

 menter, at speeds between 67 and 350 revolutions per minute, are higher 

 than those obtained by the author at these greater speeds. The 

 following table indicates the different values obtained with various 

 discs : 



VALUES OF "w" WITH SMOOTH CASING. 



