12 ENGINE TESTS. 



economy of simple, compound, and triple-expansion engines is 

 considered, also the effects of superheating, jacketing, and piston 

 speed, so far as the tests furnish data on these subjects. 



The chapters on Feed-Water Tests are followed by one de- 

 voted to Valve-Setting and Effects produced by various condi- 

 tions of operation, as illustrated by diagrams which the author 

 has taken in his professional work. The final chapter relates 

 to S.team-Pipe Diagrams, 



In connection with the matter relating to each engine, 

 whether feed-water tests, valve-setting, or otherwise, sample in- 

 dicator diagrams are presented, usually reproduced three-fourths 

 size, showing, so far as possible, average conditions. In the 

 case of feed- water tests, diagrams are given from both ends of 

 the cylinders ; but in cases of valve-setting and miscellaneous 

 diagrams, the diagrams shown are, as a rule, from only one end 

 of the cylinder. 



HOW THE FEED-WATER TESTS WERE 

 CONDUCTED. 



Before presenting the individual feed-water tests, and the 

 review of the same as noted, it is proper to give a description of 

 the methods employed in conducting them. This description 

 is of a general character, applying rather to the usual prac- 

 tice of the author in conducting these and other engine tests 

 than to each individual trial reported here. The principles, how- 

 ever, are applicable to the individual tests quite as much as to 

 the tests as a whole. In the form thus presented, not only are 

 the methods employed in conducting these tests described, but 

 methods which should be adopted in the general work of test- 

 ing, so far as they accord with the author's experience. 



The two essential quantities to be determined in conducting a 

 feed-water test are the weight of feed-water consumed, and the 

 indicated horse-power developed in the cylinder. 



