BOMBS AT BIKINI 



made ready. In the expectation that some would be 

 blown overboard, but might yet be rescued, many of 

 them were tied to floats. An identifying number was 

 marked on each can with a few crude strokes of a paint 

 brush dripping red paint. 



2. Pipe-Type Peak-Pressure Gage. This gage also 

 had been described on a previous page. The gages were 

 bolted to the superstructures of the target vessels, par- 

 ticularly the innermost vessels. 



3. Ball-Crusher Peak-Pressure Gage. This gage 

 was designed to measure very high pressures. It con- 

 sists of a strong hollow cylinder of metal, with a slid- 

 able steel rod mounted in the hollow. When the pressure 

 wave strikes, the rod is slid forcibly and strikes a 

 small copper ball, flattening it. The greater the pres- 

 sure, the harder the rod strikes and the flatter the ball 

 becomes. The degree of flattening is later measured, 

 and the pressure value calculated. Hmidreds of these 

 gages were made ready. 



4. Ruptured Foil Peak-Pressure Gage. This gage 

 was designed for intermediate pressures. It is ex- 

 tremely simple. In one common form, it consists of a 

 sheet of aluminum foil sandwiched between two heav,y 

 metal plates. The plates have previously been drilled 

 to provide a graduated series of holes of different size. 

 When the pressure wave strikes, the tendency is for 

 the exposed areas of the aluminum foil to bulge or 

 even burst. Naturally, the larger exposed areas rup- 

 ture most easily, and the small ones least easily. It is 



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