Method of Measuring Explosion Pressures. 



485 



o 



•80 



5? 



•60 



^ -4G~ 



0.-20 



Fig. 10. 



l'0 20 30 



D/std/?ce in Feet. 



Variation of Pressure with Distance. 

 Displacement of 1 cm. =1600 lb./sq. inch. 

 Explosion Pressure of 24; lb. Guucotton. 



40 



Table II. 



Plate No. Maxim » ra -Pressure Distance from p Dist a n ce. 



• m cm. displacement. charge. 



132 0-80 6 feet. 4'8 



133 0-54 9 „ 4-8 



135 0-55 9 „ 4-9 



137 060 9 „ 5-7 



138 0-54 9 „ 48 



VI. Velocity of Propagation of Explosive Wave 

 in Water. 



The velocity of the explosive wave was measured in two 

 different ways. In the first method two detector vessels 

 were placed at a fixed distance apart, — 24 feet in most cases, 

 and the explosion detonated 12 feet from one of them in the 

 same straight line. Both vessels were attached to the same 

 lead connected to the oscillograph, but the detecting vessel 

 A nearest the charge was made so that a pressure wave 

 generated a positive charge in it, while the other B produced 

 a negative charge when the pressure was applied to it. This 

 arrangement caused the spot to be deflected to the right side 

 of the zero line by the pressure on A and to the left when i: 

 reached B. The first and second vessels were thus easily 

 recognized on the plates, and the time interval between the 

 two maximum pressures due to A and B gave the time for 

 the wave to travel 24 feet. The velocity is then directly 



