1070 
-2e 
extinction of successive flames was obtainea from direct measurements mage on the negatives 
using a dcublo-traverse microscoos. Time-disolacement curves were drawn from these figures 
and velocities deduced in the usual way by drawing tangents. The results are shown graphically 
in Figures 3 ano 4, 
Discussion of records. 
LEN MANES NBS 
On examination of Figures 1 and 2, a faint curved trace will be observed crossing both 
photograohs. In Figure 1 the curve oasses through the terminations of the jet traces. This 
trace, which is present on those records which were taken under bright weather conditions, is 
attributed tc sunlignt reflectcd intc the camera lens from the atomis2d soray forming the apex 
of the water olume. If this exclanation is correct the trace is, therefora, in effect a time 
displacement curve for the rising water surface, water surface velocities have been calculated 
from the records on which the trace is sufficiently distinct, ana they are shown graohically in 
Figure 4. 
A separate shock wave in air was not detected on any of the records taken with the charge 
2 inches below the water surface, the jets being extinguished by the water olume. For this 
reason the velocities odtained at this depth have been clotted as water—surface velocities on 
Figure 4, 
The comoaratively small difference between the water surface and shock-wave velocities 
when the Charge is detonated 4 incnes below the surface, sugyests that a detached shock wave 
would not be detected for geoths cf immersion much less than 4 inches, 
The results optaine at the 2 inches decth from the two reccras taken with different jet 
arrangements were In very close agreement, and they have been plotted as a single curve in 
Figure 4. 
Finally in Figure 2, tne shape cf the flame traces after deflection by the shock wave is 
of some interest. The abruot Changes in sloce aocarent in some of the flame traces may be taken 
as a measure of corresconding changes in carticle velocity occurring in the air zone between the 
shock-wave front and the rising water surface. 
