78 



In brief, he found that a nozzle of form specified in Fig. 2 (called a 

 14 inch nozzle), in combination with a 2 inch flat disc, would regulate the 

 pressure in a % inch pipe to the following extent: 



The pressure on the down-stream section of the pipe was preserved 

 constant at 2^,2 pounds by the action of the disc while the pressure of the 

 up-stream section varied between 10 to 40 pounds per square inch by gauge 

 (as sliown on Fig. 4). 



FlQ^ 



APPARATUS. 

 Fig. 1 shows the construction of the apparatus with nozzle, disc, cham- 

 ber and spider for supporting the disc. The fitting of the apparatus for 

 experimental work is shown in Fig. 3. The two gauges for measuring 

 the pressures were placed as close as possible to the chamber containing 

 the disc. The fittings were made with great care. The valves shown were 

 for controlling the pressures used in experimentation. 



METHOD OF EXPERIMENT. 



The apparatus was attached to the standpipe of the hydraulic lab- 

 oratory, the pressure in which Avas controlled by a steam pump. Start- 

 ing with a given standpipe pressure, say 40 poimds, the water was 

 allowed to flow through the apparatus, being throttled by the lower valve 

 to indicate a down-stream pressure of, say 2i/o pounds per square inch on 

 the lower gauge. This down-stream pressure was allowed to remain 

 fixed during the test, the lower valve not being disturbed. The up-stream 



