37 121 
Reckoning time in thousandths of a second from the moment of detonation, the 
order of events in the above experiment is as follows:—The main wave reaches the 
gauge at t = 10 and forces in the detent, at the same time holding the shutter from 
movement ; the tension wave from the surface arrives at the gauge att = 18, and 
takes the pressure off the shutter; the shutter then begins to turn and completes its 
movement at t = 25; the reflected wave from the bottom arrives at the gauge at 
t = 37, and drives in the two pistons; the crushing of the leads indicates that the 
velocity of the pistons at the moment of impact is about 15 feet per second, so that 
impact must occur after t= 47, but probably not later than t = 50; the period of 
ten thousandths of a second during which the piston is in movement should be ample 
to cover the duration of the wave ; finally, the wave reflected from the bottom reaches 
the surface and is reflected as a wave of tension, which arrives at the gauge at t = 52, 
just after the pistons have hammered the leads. 
