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man, as well as of gain to the master, and may be employed 

 independently of the use of galvanism, being equally effec- 

 tive as respects resistance, whether this or the old fuse be 

 used. 



One great advantage, gained by the use of galvanism, and 

 which cannot be attained by that of any kind of fuse or 

 match whatsoever, is the certainty with which any number 

 of charges may be fired at the same instant of time ; for 

 suppose it were attempted to fire eight or ten charges simul- 

 taneously by the aid of fuse, it would be absolutely impossible 

 so to arrange their length as to cause an ignition of all the 

 charges at the same moment, and if the explosions are not 

 absolutely simultaneous, no advantage is gained over the 

 firing of these several charges at distant intervals of time. 

 But when galvanism is used, there is a complete simultaneity 

 of explosion, because electricity travels at such a prodigious 

 rate, (200,000 miles in a second,) that its transit from one 

 hole to another in the rock is to us instantaneous. We gain 

 much by rending a rock in this manner, for the fracture runs 

 in one continuous line, and a far greater quantity of stone is 

 torn off than could be done by the same quantity of powder, 

 if fired at distinct intervals ; indeed, the amount of rock that 

 can be rent with a small quantity of powder by these simul- 

 taneous explosions, is more than persons would believe, had 

 they not witnessed it. I had at first considerable difficulty 

 in contriving the apparatus to ensure a certainty of firing 

 many charges at once, but every obstacle has now been 

 overcome, and the practice is perfectly easy. Another 

 advantage gained by the use of the galvanic cartridge, is the 

 ignition of all the particles of powder in the main charge at 

 once. It is perhaps unknown to some of you, that gun- 

 powder does not explode with flame and gas ; on the con- 

 trary, it burns progressively — thus, when a gun is fired, 

 many grains of powder are blown out unignited and untouched 



