1839] Memorandum of Experiments, fyc. 85 J 



My apparatus was thus prepared, see fig. 7 — fifteen inches of the 

 thick end of a gun-barrel g, g, were cut off, and a male screw turned on 

 the barrel near its centre. To this screw was fitted a square plate of 

 iron, half an inch thick by about five inches square i, i, having a hole 

 at each angle to admit of fastening screws being inserted. A teak 

 rod t, t, eighteen inches long, was now prepared so that it would just 

 enter the gun-barrel when nearly red hot — two grooves were cut in 

 the opposite sides of this rod, and the conducting wires let into the 

 grooves and securely fastened in with a strip of wood and pitch cement. 

 The rod and wires were then driven into the hot gun-barrel, and the 

 whole immediately plunged in cold water. The contraction which 

 ensued bound the rod and wires so firmly that no force could possibly 

 affect the platinum loop, nor any leakage occur through the iron tube. 



An inch and a half of platinum wire {p) was next soldered to the end 

 of the conductors, and over these was tied a paper cartridge containing 

 mealed Dartford powder — the cartridge was protected by a copper tube 

 G, which screwed on to the end of the gun-barrel, and projected about 

 three inches beyond the platinum loop. This tube was filled with 

 Dartford powder and securely closed by a wooden stopper, cemented 

 into its place by melted pitch. 



The ignition of the platinum wire would explode the cartridge, and 

 this the surrounding Dartford powder, which must burst the tube 

 and explode the contents of the mine in which it was placed. 



I may here advantageously anticipate the regular course of this 

 narrative by stating, that the mine for the destruction of the " Equitable" 

 consisted of a barrel-shaped wooden vessel, about seven feet long by 

 three and a half feet in diameter, capable of containing 2,5001bs. of pow- 

 der. The square iron plate i 9 i, fig. 7- B, was screwed into the side of 

 this vessel, which was subsequently enclosed in thick sheet lead. Into 

 the iron plate the priming tube, above described, was firmly screwed, 

 a washer of lead being placed in the joint. 



Description of self-acting apparatus for igniting the wire at any given 



moment. 



In compliance with the wishes of Captain Fitzgerald, the engineer 

 officer in charge of the operations for destroying the wreck, it was 

 determined to sacrifice the battery employed, by placing it immediately 



