644 



SCIENCE. 



[Vol. II., No. 41. 



the Avorking-fiices of the valve, as shown in 

 fig. 4, in which S sliows the steam space, and 

 i' the exhaust space. By this an-angenient 



the valve-stem is packed against the exhaust 

 instead of the steam pressure. The valve is 

 ground to a sliding-fit, and, so far as I can 

 ascertain, there has not been a particle of wear 

 or leak during the ten months the engine has 

 be#n in operation. 



The governor of the engine, that part 

 which makes it espeeiallj' valuable for the 

 purpose of electric lighting, is represented in 

 fig. 5. 



This automatic device is fixed in the fl3'- 

 wheel, whicli is ke3-ed to the shaft. There are 

 two eccentrics, E and F, the one within the 

 other, and both free to move on the axis. There 

 are two weights, with their centres of motion 

 opposite, and fixed in arms of the wheel. These 



centrifugal force of the weights. The system 

 is so constructed that any centrifugal motion 

 of tlie wciglits will throw one eccentric ahead 

 and the otlier back, thus dimin- 

 ishing the tlirow of tiie eccen- 

 trics, and effecting a shorter 

 cut-off without altering (with- 

 in working limits) tlie lead of 

 the valve. The engine used 

 on board the Albatross has 

 eight inches and a half di- 

 ameter of cylinder, and ten 

 inches stroke of piston : it runs 

 without noise, three hundred 

 revolutions per minute, requir- 

 ing no more attention than the 

 oiler can give it in addition to 

 his other duties. When the 

 main engines of the Albatross 

 are in motion, a boiler-prees- 

 ure of sixty-five pounds is often 

 used, and twentj'-six inches of 

 vacuum is scarcely above the 

 average. Lying in port, the 

 boiler-pressure is kept at about 

 twentj'-five pounds ; and, not- 

 withstanding this great range of pressure, 

 the governor regulates the dynamo to three 

 hundred revolutions per minute, as closely a& 

 I can measure it. 



In selecting a good engine, Edison has, 

 to my mind, disjjlayed as much genius as in 

 using the Siemens form of armature for his- 

 dynamo. 



The engines are placed on the starboard side- 



weights, W, W, are connected, each to an 

 eccentric, and are connected together by an 

 arm or rod. Springs are provided, to resist the 



of the main engine-room, tlie engine taking- 

 steam from the main boilers, and exliausting 

 into the main condenser. 



The dynamo used on board the Albatross is- 



