589 
19 
TABLE 1 
Description of Cables Subjected to Underwater Explosions, 
Es. Manufacturer's 
Letter; Designation 
Belden 8421 
Belden 8401 
Belden 8216 
Precision 
Cable E 
Precision 
Belden 1637 
Belden 8863 
Insulation 
Rubber 
Rubber 
Rubber 
Fiber-glass 
Fiber-glass 
Fiber-glass 
and 
Celluloid 
Rubber 
Rubber, 
Cotton 
Shield 
Copper 
Stranding 
Copper - 
Phosphor- 
Bronze 
Stranding 
Copper 
Stranding 
Copper 
Tube 
Copper 
Tube 
Copper 
Tube 
Copper 
Tube 
Copper 
Stranding 
and Peak Voltages Produced by These Cables 
Sheathing pace nee per foot 
inches wut 
Rubber 
Rubber 
Rubber 
None 
None 
None 
None 
None 
* The peak voltage was determined from at least four trials with each cable. 
10 to 136 millivolts. 
Greater signals were produced by the rubber-sheathed 
cables than by the unsheathed ones, the former ranging from 80 to 136 milli- 
volts, the latter from 10 to 40 millivolts. 
were 2 or 3 milliseconds. 
These large cable signals may give rise to important errors when 
used in conjunction with a crystal pickup in measurements on the initial part 
of the pressure pulse in an underwater explosion. 
Typical durations of the signals 
Even larger relative er- 
rors will result, however, in pressure determinations during the ensuing pe- 
riod of several milliseconds characterized by distinctly lower pressures. The 
character of the tail of the curve corresponding to this later period may be 
completely masked by cable distortion. 
the area under the pressure-time curve must be determined, and since the du- 
ration of the cable pulse is long compared to that of the true pressure pulse, 
a tail area of considerable size would make a large spurious contribution, 
say as large as 20 per cent, to the measured impulse. 
The lowest signals, 10 and 13 millivolts, were produced by the 
cables designated as D and E respectively, see Table 1. 
When measuring impulse or momentum 
The shielding in 
both consists of copper tubing rather than stranding; they have fiber-glass 
insulation, their outside diameter is small, 0.100 inch and 0.125 inch re- 
spectively, as compared to those of the other copper-tube cables tested, and 
