HELL-GATE, IMPROVEMENTS AT. 



475 



of the drill-holes, the car- 

 tridges were dipped in 

 melted resin, heeswax, and 

 tallow. After being loaded, 

 they were soldered with a 

 steam-heated iron, were re- 

 moved as fast as they were 

 filled, and were carried to 

 the mine in boxes contain- 

 ing twenty each ; so that 

 the amount of mixed ex- 

 plosive above - ground at 

 any one time was never 

 enough to do more than 

 local damage in case of an 

 accident. These cartridges 

 were inserted in the drill- 

 holes, one after the other, 

 till the holes were filled, 

 the last cartridge in every 

 case being filled with dy- 

 namite, with its end left 

 to project about six inches, 

 so that it might receive the 

 full effect of the shock from 

 the initial charges connect- 

 ed with the battery. This 

 cartridge is 15 inches long 

 and 2J inches in diameter. 

 In its forward or projecting 

 end is inserted a small cop- 

 per shell filled with ful- 

 minate of mercury. The 

 other cartridges, charged 

 with rack-a-rock, are 24 

 inches long by 2 inches in 

 diameter, and are provided 

 at their forward ends with 

 a fulminate primer which 

 is inserted after they are 

 filled. This primer consists 

 of a fulminate exploder in 

 a copper tube containing 

 an ounce of No. 1 dyna- 

 mite. The cartridges are 

 secured in the holes by di- 

 vergent wires at their low- 

 er ends; and the dynamite 

 cartridge is also fastened 

 with wooden wedges. The 

 mine-exploder consists of a 

 brass cylinder, eight inches 

 long by two in diameter, 

 filled with dynamite. In- 

 closed within the dynamite 

 is a fuse, the wires from 

 which pass through a di- 

 vided cork in the mouth of 

 the brass cylinder. It con- 

 sists of a copper tube nearly 

 filled with 30 grains of ful- 

 minate of mercury. Fitting 

 in the open end of this tube 

 is a second tube contain- 

 ing sulphur, through which 

 pass the two conducting- 



