ENGINE No. 79. 



Four valve (Corliss), cross compound, 24" and 44" x 72." 

 Speed, 61 revolutions per minute. 



The main object in changing the adjustment of the valves in 

 this engine was to secure a greater amount of compression, and 

 a more quiet operation of the engine. Previous to the changes 

 there was considerable knocking in the main connections when 

 the centers were passed, and internal noises in both cylinders. 

 The effect of the changes was to almost wholly overcome these 

 defects in the running qualities. The adjustments consisted 

 in moving the eccentric of the high-pressure cylinder forward 

 \\ rr on the 12" shaft and the eccentric of the low-pressure 

 cylinder forward l." The steam-valve rods of the high-pn -s- 

 sure cylinder were both shortened two threads, so as to give 

 earlier admission. The exhaust rods of the same cylinder were 

 lengthened 8 threads each, so as to increase the compression. 

 The steam-valve rods of the L. P. cylinder were shortened three 

 threads each, so as to give earlier admission : and the exhaust 

 rods were each lengthened 6 threads, so as to obtain earlier com- 

 pression. To letter reveal the effect of the changes, the dia- 

 grams are superimposed, the dotted lines being taken before, 

 and the full lines after, the adjustments. 



300 



