In conjunction with this depth-detecting device it is equally 

 feasible to have sonne sort of system for opening and closing nets. 

 Initially, we felt a solenoid would be the simplest and nnost sat- 

 isfactory device. Later, we abandoned this approach because of 

 the frictional effects and the resulting large power requirements 

 and selected a simpler means of turning the damper. An 

 EXPLOSIVE SQUIB was used as a wedge to hold the damper 

 door in various positions (fig. 18. 10). These squibs contain a 

 half grain of black powder which is fired by an internal elennent 

 energized through two external leads. The outer case of the 

 squib is of sufficient strength to withstand water pressures up 

 to at least 2,000 meters and at the same time to arrest the 

 spring-loaded dampers. Such an arrangement allows the obser- 

 ver on the vessel to lower his net to a desired depth, fire the 

 first squib to start the sampler fishing, and then fire the second 

 squib to close the sampler. 



FIGURE I O* 10 

 EXPLOSIVE SQUIB 

 RELEASE MECHANISM 



208 



The damper is in the open (fishing) 

 position, one squib haring been fired. 

 When the second squib (which can be 

 seen) is fired, the spring trill turn 

 the damper on aro\isd, counterclockwise, 

 and effect the closure* 



