AMERICAN STEAH ENGINEERING. 



BY PHILIP DAWSON. 



[Philip Dawson, engineer; born in Paris, and educated in continental schools graduat- 

 ing at Ghent and Liege ; made an exhaustive study of traction work in the United 

 States, Canada, and the continent during 1894-5; has been intimately connected with 

 the carrying out of the following power stations and traction contracts: Bristol, 

 Dublin, Cork, Liverpool, London limited, Central London, Glasgow, Liege, Rheims, 

 etc. Author of many technical papers and published volumes. The following article 

 is republished from the Engineering Magazine.] 



American steam engine power house practice may prop- 

 erly be taken up from the point of the introduction of the 

 Coriiss valve. Probably the most important development 

 in steam engineering since the days of James Watt was made 

 by Joe Corliss in 1849, when he introduced his now so famous 

 drop cut-off valve gear. The main features of this gear were 

 the rapid and wide opening of the steam ports, the shortness 

 and directness of these ports (which reduced the clearance to 

 as little as 2J per cent of volume in the high pressure and 4 

 per cent in the low pressure cylinder), the quickness of closure 

 of the steam valves, and the adaptation of the main valve to 

 the functions of a cut-off valve. This type is eminently a slow 

 revolution engine — for small sizes, not above 250 kilowatts, 

 reaching as many as 135 revolutions per minute, for 800 kilo- 

 watts as much as 100 revolutions, for sizes up to 1,000 kilo- 

 watts running as high as 90 revolutions, and for larger sizes 

 not above 75 revolutions per minute. 



In the early days of dynamo construction up till, we may 

 say, ten years ago, generators were small, a machine of 500 

 kilowatts being considered enormous, whereas generators 

 of as much as 5,000 kilowatts have been installed to run the 

 Manhattan elevated railway at New York. The smaller 

 d5niamos of earher days were all bipolar, running a very 

 large number of revolutions, certainly above 200, per minute. 

 Accidents to the electrical portions were frequent when it 

 was customary, as it was in large installations, to drive two 

 or more dynamos off one engine ; and indeed in traction stations 



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