ENGINE No. 72. 



Four valve, 16" x 36". Speed, 72 revolutions per minute. 



This engine has two double-poppet steam valves, and slide 

 valves for the exhaust. They are driven through a train of 

 gears. 



The gear which drives the valves was changed, with a view 

 to securing compression of the exhaust steam up to the initial 

 pressure, being moved forward, thereby hastening the release 

 as well as the compression. This change was made with the 

 object of studying the effect of compression upon the actual 

 economy of the engine under conditions of practically the same 

 load. So far as this test showed anything, under these condi- 

 tions, there was in reality a slight increase in the amount of 

 feed-water consumed per horse-power per hour, attending the 

 earlier compression. The diagrams were taken from the crank 

 end, No. 72a before, and No. 725 after, the change. 



ENGINE No. 72a 



ENGINE No. 72b 



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