ON GASEOUS EXPLOSIONS. 185 
Indicator Diagrams. 
In each trial two indicator diagrams were taken—namely, a com- 
plete diagram showing the pressure and volume during the. whole 
cycle, and a diagram taken with a thin dise stopped down so as to 
give on a large scale the portion of the diagram during the pumping- 
stroke. The diagrams are in general calibrated in situ. 
° 
° 
+ 
° 
N 
- 
° 
= 
3 
3 
° 3 ss 
oa g e 
¢ ta 
matin 
° oO 
a 3 
+ 249-75 lbs O” 
Fra, 5. 
+ 199:75 
+ 149-75 
+t 99-75 
+ 49°75 
Ats 
Fia. 6. 
In carrying out a series of experiments, however, it was found that 
the scale was so constant that it was unnecessary to calibrate each 
diagram separately. The scale was therefore made for the two discs 
used, and was checked from time to-time. A pair of typical diagrams 
