328 ENGINE TESTS. 



average pressure. At a point just beyond the middle of the 

 stroke the pressure gradually falls, until just before the end 

 of the forward stroke it suddenly rises again preparatory to 

 the beginning of the return stroke. 



This diagram is a curiosity for the reason that the pressure 

 rises at the very beginning of the stroke, when presumably the 

 cylinder is taking steam, whereas under the ordinary cir< Mini- 

 stances it would be expected that the operation would be 

 reversed and the pressure would fall. The probability is that 

 owing to the compression of the exhaust steam into the clear- 

 ance space the quantity of live steam admitted is very small. 



Another curiosity in this diagram is the fall of pressure 

 from the middle to nearly the end of the stroke. During this 

 period there is no steam being drawn i>ut of the pipe, and the 

 only explanation of this action is tin- assumption of a sort of 

 rebounding of the steam within the pipe due to the intermit- 

 tent character of the flow. In this matter as well as in the 

 conformation of the diagram ilm>u:_;-h.>ut, tin-re are many points 

 which, to say the least, are nl.smre. 



