864 



EXPLORATION GEOPHYSICS 



the access of water to the explosive immediately surrounding the cap. 

 Occasionally, it is desirable to use tape for the further protection of the 

 cartridge at this point. 



Where more than one cartridge is to be loaded into a shot-hole, it is 

 desirable to assemble the several cartridges into a unit to facilitate handling 

 and loading. Some of the explosive companies have developed and incor- 

 porated in their products special screw-thread or quick-locking ends for 



Fig. 537. — Screw thread cartridges for assembly into a single stick 

 of explosive. (A), cartridge; (B), screw thread. 



assembling cartridges. These generally offer a quick and simple means of 

 assembling a coupled column of explosives. f Figure 537 shows one type 

 of screw-thread cartridge. 



The cap wires should be secured to the charge in a manner that will 

 prevent strain at the point where the wires enter the cap. The assembly 

 also should be such as to prevent strain or pull on the cap wires where 

 they enter the cartridge. The wires may be looped or hitched around the 

 cartridge, sharp bends or kinks being avoided. (Figure 538.) In shallow 



t W. F. Smith, "Connecting Means for Explosive Cartridges," U. S. Patent 2,429,079, Oct. 14, 



r. 



L. B. Counterman, "Explosive Cartridge Unit," U. S. Patent 2,425,176, Aug. 5, 1947. 



