SCIENTIFIC OFFENSIVE 



ample, an overpressure of only a few pounds per square 

 inch might reduce the can's vohime to 80 percent of 

 the original volume ; but a more extreme overpressure 

 might reduce the volume to 10 percent. Cans are cheap ; 

 hundreds may be used, and the average effect can be 

 measured with accuracy. (The decrease in the can's 

 volume could be measured simply by filling the can 

 with water, weighing it, and making a comparison 

 with the weight of a filled tmcriished can). Many other 

 instruments were equally ingenious. 



Dr. Penney and his assistants, collectively known 

 as the Pressure Group (Cans and Drums), experi- 

 mented with other gages of equally crude sort.* They 

 were especially keen to hit upon gages good for meas- 

 uring very high pressures. One type developed con- 

 sisted of a sort of pan-pipes or harp, of small pipes 

 of graded lengths. When the pressure wave strikes, 

 the pipes are bent; long thin pipes bend most, and 

 short fat pipes least. With the help of laboratory ex- 



* This Group included six subgroups, as follows: 

 Air Blast Subgroup, headed by Dr. C. W. Lampson 

 Underwater Subgroup, headed by Dr. A. B. Arons 

 Low Frequency Subgroup, headed by Dr. J. V. Atanasoff 

 Radiometry Subgroup, headed by Comdr. S. S. Ballard 

 Pressure-Time Subgroup, headed by Dr. J. E. Henderson 

 Service Subgroup, headed by CWO J. P. Orr. 

 Captain L. W. McKeehan (Navy) served as Adviser. Personnel 

 was drawn principally from the Navy's Bureau of Ordnance, the 

 Naval Research Laboratory, and the David Taylor Model Basin; 

 pressure experts were borrowed also from various U7iiversities, 

 notably the University of Washington in Washington State. 



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