129 



Now, all chance of loss in this manner is avoided by the 

 use of electricity in firing the powder, because the fluid 

 passes through a solid wire to the charge, and no aperture 

 whatever being left in the tamping stuff, the consequence is, 

 that the whole force of the explosion is expended upon the 

 rock; it has no other mode of escape, except by blowing 

 out the tamping stuff altogether, an accident which can be 

 avoided by the adoption of another improvement, which I 

 will presently explain ; but if the old mode of tamping is 

 used, this blowing out of the stuff is of frequent occurrence, 

 because the workmen, knowing the operation to be one of 

 danger, hurry it over and perform it inefficiently. The 

 dangers I have described are avoided by the use of gal- 

 vanism in firing the charge, because the apparatus is so 

 contrived that it is impossible the powder can be ignited 

 before the workmen expect, and they have time to secure 

 themselves ere the explosion takes place. Should any acci- 

 dent occur to prevent the charge from going off, the battery 

 can be thrown out of action by pulling a cord, and then there 

 is no danger in approaching the rock, for electricity never 

 hangs fire. 



It is now five years since I introduced blasting by 

 galvanism into the mining districts of Cornwall, but the 

 apparatus I then used was imperfect, as I had much to learn 

 by observation and experiment. I subsequently made further 

 improvements in the machine, and employed it with great 

 success in Scotland, both in quarries and under water. After 

 this General, then Colonel, Pasley found the same process 

 very efficient in his operations against the Royal George, at 

 Portsmouth. It then came into frequent use in all parts of 

 the country, and I have now further increased its practical 

 simplicity, as will be shown to you this evening. 



Electricity, when generated by means of the contact of 

 metallic plates and a liquid, is, for the sake of convenient 



