Page 621 



RADIO ACOUSTIC RANGING 



664 



slightly smaller than the opening in the can, should be used, although hand packing is 

 satisfactory. After the cans have been filled, the punched tops (see 662) are pressed 

 on, the excess TNT is removed, and the preliminary preparation of the bombs has been 

 completed. 



TNT should be poured through a funnel into any container with a small hole. A 

 small stick may be used to pack the loose TNT and, after packing, the container is again 

 filled and repacked, and the procedure is -repeated until the container is fully packed. 



A number of containers may be filled with TNT before the bombs are needed, but 

 detonators and fuses must never, under any circumstances, be inserted at this time. 

 The filled bombs are stored in a carefully selected safe place, but the detonators are not 

 inserted until just before a bomb is to be used (see 6842.) 



The approximate cost of the materials in the difterent size tin can bombs in 1940 

 was as follows: 



Size 



Container 



TNT 



Fuse 



Lead 



Detonator 



Total cost 



)^8pint 1.3^ 2.5^ 0.5^ 0.6^ 1.7^ 6. 6f^ 



Kpint 1.5 5.0 0.5 1.2 1.7 9.9 



Kpint 2. .3 10.0 0.5 2.4 1.7 16.9 



1 pint 2.5 20.0 0.6 4.8 2.2 30.1 



1 quart 3.5 40.0 0.6 9.5 4.4 58.0 



The above costs are based on the following prices: Pig lead at 5.6^ per pound; 



TNT at 20^ per pound; No. 6 detonators at $17.00 a thousand; No. 8 detonators at 

 $22.00 a thousand; fuse at $6.30 a thousand feet. 



664. Deep-Sea Bomb 



SINGLE CONDUCTOR. 



RUBBER INSULATED CABLE 



CONNECTED TO 



BRASS SCREW AND NUTS 



RUBBtR TAPE 



PARA' RUBBER TAPE 



HARD RUBBER STOPPER 



In R.A.R., bombs are usually made to ex- 

 plode approximately at the depth of the hydro- 

 phone (see 6843) , but under certain conditions 

 and in experimental investigations it is some- 

 times desired to explode bombs at great 

 depths. The best way of doing this is with an 

 electric detonator, for TNT bombs cannot be 

 detonated by fuse in depths of water much 

 greater than 25 fathoms. Below this depth the 

 increased pressure prevents the powder train 

 in the fuse from burning and misfires result. 

 It is possible to protect the fuse in a capped 

 pipe screwed into a metal bomb container, but 

 the construction is expensive and time-con- 

 suming. 



The type of bomb illustrated in figure 139 

 has been successfully detonated at a depth of 

 700 fathoms. Any type of heavy glass bottle 

 or thick metal container, with an opening into 

 which a rubber stopper may be inserted, may 

 be used in its construction. One of the electric 

 leads of the detonator is attached to the head 

 of a brass screw (No. 8-32) which passes through the stopper. The other lead passes 

 between the stopper, which is slightly grooved, and the container, to make contact with 



SECOND DETONATOR 



LEAD EXPOSED 



TO WATER 



HEAVY GLASS 

 OR METAL CONTAINED 



Figure 139.— Bomb for deep detonation. 



