1. A. M. Worthington,A Study of Splashes(Longmans Green and Company, New York, 1908).
2. R. M. Davies, “Influence of atmospheric pressure on the phenomena accompanying the fall of small scale projectiles into a liquid” (Engineering Laboratory, Cambridge, England, 1944).
3. This equality, p = pA, holds except for an underpressure of the order 12ρAV2 (V = projectile velocity), which is considerably smaller than pA at the velocities we are considering.
4. The need for the use of dense gases was first pointed out by Professor Garrett Birkhoff.
5. For velocities greater than 20 ft.∕sec., errors caused by neglect of gravity are less than 1 percent when steel spheres of 14-in. diameter are considered.