BULLETIN OF THE UNITED STiTES FISH COMMISSION. 153 



75.-AIVIVVAIi REPORT OIV THE KJiECTRIC Y^IOnTINQ OF THE 

 UNITED STATES 8TEAmER AI.BATRONS, £>ECEiTIBER 31, 1S83. 



By Passed Assistant £ng:ineer O. IV. BAIRD, U. 1^. IV. 



[R68um6 of the quarterly reports.] 



The steadiness and uniformity of brightness of the lamps depend 

 largely (almost entirely), on the engine driving the dynamo, and the 

 success of the system lies more in the attention paid to the engine, 

 where the plant is correctly installed, than anything else. Uniformity 

 of speed is the great object sought, and to secure this Mr. Edison has 

 adopted a highspeed engine, with a sensitive governor, represented in 

 Fig. 1. 



This engine has a single steam-cylinder, 8^ inches in diameter of bore, 

 and a stroke of piston of 10 inches ; it runs 300 revolutions per minute 



Fig. 1. 



very uniformly, the automatic cut-off regulating the quantity of steam 

 admitted to the load on the engine. This particular engine is larger 

 than should be employed for this plant, as the short cut-off at high 

 pressures and light loads causes great cylinder condensation, not only 

 diminishing the economy of the engine, but causing such incessant ham- 

 mering in the cylinder that I have been obliged to introduce a pressure- 

 regulating valve (Fig. 2), which limits the pressure to what is desired. 

 Previous to introducing this valve, two cross-head keys had been 

 sheared off and one cross-head broken, by water in the steam-cylinder. 



