80 



Some experiments were carried on with air as the fluid passing 

 through the pipes. With the nozzle and discs usetl there appeared to be 

 no governing eiifect, in case of these air pressures. 



In general it may be said that the shape of the nozzle has most to 

 do with the action observed. A number of nozzles of different form were 

 used; those most nearly lil^e that sliown on Fig. 2 gave the best governing 

 effect. 



The size of the disc affects the results obtained with any given nozzle. 

 Two-inch disc gave better results than 1-inch or the li/^-inch disc. 



The action desired could be obtained with water at a temperature of 

 75° F. as well as at the higher temperatures. 



A very pretty cylindrical sheet of water could be obtained by remov- 

 ing the lower part of the casing. The disc acted like the well-known ball- 

 nozzle. Under these conditions, with a head pressure of 40 pounds and a 

 nozzle velocity (as figured from the discharge) of 14.6 feet per second, it 

 was found necessary to exert a force of 9 pounds to pull the disc from 

 the jet. 



WATER. 



