334 ENGINE TESTS. 



diagram 966 was taken the 10" pipe was shut off at the boiler 

 end, and steam was furnished through twenty-five feet of 8" pipe 

 and one 45 degree elbow into a tee at the boiler end of the 10" 

 main. In both these diagrams the admission of steam is accom- 

 panied by a drop of pressure in the pipe, as would be expected, 

 and a corresponding rise of pressure at the point of cut-off. In 

 diagram 96a the pressure falls again very quickly after cut-off ; 

 and a succession of wavy lines occur until the middle of the 

 stroke, and then the pressure is nearly constant to the end. In 

 diagram 96ft, on the contrary, the fall of pressure just after the 

 cut-off is much less marked, and there is considerable more rise 

 in pressure as the end of the stroke is approached. The only 

 difference in the conditions under which these diagrams were 

 obtained was in the lengthened pipe through which the steam 

 passed. It would seem, therefore, that the arrangement of the 

 pipe has much to do with the character of the fluctuations. 

 It will be noticed also in these diagrams that the fluctua- 

 tions resemble in some respects those which occur on previ- 

 ous diagrams taken from a pair of engines with both cylin- 

 ders running. In this case, however, only one cylinder was 

 in operation. Here is another indication that the arrangement 

 of the pipe has much more effect upon the diameter of the 

 fluctuations than would at first be supposed. 



