Viewing page 107 of 212

This transcription has been completed. Contact us with corrections.

37.

[[underlined]] experiments in which the lift exceeded 4 cm. are from 300 to 600 ft/sec. too small [[/underlined]]. This is a very important conclusion, for it means that the highest velocities in vacuo, recorded in Table III, are [[underlined]] doubtless considerably less than those which were actually attained [[/underlined]].

5. A comparison of the results obtained by means of the circular tank with those obtained by means of the cylindrical tank shows that the velocities range about 100 ft/sec. higher for the circular tank -- a difference that is so small as to be well within the accidental variations of the experiments.

Concerning the behavior of the cylindrical tank under different conditions, a comparison of experiments shows that the velocities are much the same for all cases. Hence it is safe to conclude that the rebound, at least for small charges, is not excessive even if an empty tank is used, providing it is sufficiently large.

A check of some interest, on the effectiveness of the cylindrical tank, with the retarder, [[underlined]] J,J' [[/underlined]], in position inside, was the sound of the shot, which resembled a sharp blow of a hammer on the [[underlined]] lower [[/underlined]] cap of the 12-inch pipe. The impact was most clearly discernible when the hand was on the lowest part of the tank. The sound, in the case of the circular tank, did not appear to come from any particular part. When the tank was grasped during firing, a throb of the entire tank was noticed.

6. Concerning the proportion of the measured reaction that is due to gaseous rebound, the tissue paper detector, as has already been explained, does not give any information. All that this detect[[strikethrough]]ion[[/strikethrough]] ^[[or]] really shows is that the [[underlined]] force [[/underlined]] exerted by the initial upward rush of gas past the chamber is not excessive. The fact that