1544 
10.2 The experimental records obtained in this program unfortunately 
do not provide an adequate test of the theory developed above. 
The ranges are such that the expected rise times would be some- 
what less than the transit time across the gauge, and the recording 
speed was such that the rise of the record is not highly resolved. 
Furthermore, it proved very difficult to keep the oscilloscope 
tubes rigidly aligned so as to make the spot deflection accurately 
normal to the plane of rotation of the film drum. Thus, the 
measured rise time on many records is grossly in error because of 
the presence of a slight tilt of the "vertical" axis and in general 
the scatter is extremely large. One can only eanenude from the 
records that the recorded rise time is of the order of the transit 
time across the gauge, but it is impossible to obtain values 
precise enough to justify subtraction of the gauge transit in 
order to estimate the actual rise time of the pressure wave. 
There now exist very long range data, obtained during the 
Spring of 1949 by Dr. E. Swift's group of the Naval Ordnance 
Laboratory Explosives Division. Some preliminary tracings which 
Dr. Swift kindly supplied the authors seem to correspond to the 
wave shapes of Figure 14, and the rise times are of the order 
predicted by the theory, but these remarks are based on the exam- 
iriation of a few isolated records rather than on an analysis of all 
the data now available. It is possible that a complete analysis 
of the NOL records will afford a more critical test of the theoret- 
ical results than the data so far available. 
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