130 BLASTING UOCKS. 



of going to work with a mass so firmly bound together as a line of battle 

 ships, that even the action of 57 years of decay under water goes but a 

 small way to disintegrate the parts. The manly perseverance of Colonel 

 Pasley, therefore, we are well convinced, will, in the end, effectually clear 

 the noble anchorage of Spithead of this extremely troublesome obstruc- 

 tion." 



Upon an after examination by the divers, when the tide permitted, it 

 was found that the explosion had been most successful; since which 

 time several other explosions have taken place, from the effects of 

 which vast masses of the wreck have been forced to the surface of the 

 water, and the anchorage cleared. 



BLASTING ROCKS UNDER WATER BY MEANS OF THE DIVING BELL. 



In this process three men are employed in the diving bell, one holds the 

 jumper or boring iron, which he keeps constantly turning, the other two 

 strike alternately quick smart strokes with hammers. When the hole is 

 bored of the requisite depth, a tin cartridge filled with gunpowder, about 

 two inches in diameter, and a foot in length, is inserted, and sand placed 

 above it. To the top of the cartridge a tin pipe is soldered, having a brass 

 screw at the upper end. The diving bell is then raised up slowly, and 

 additional tin pipes with brass screws are attached, until the pipes are 

 about two feet above the surface of the water. The man who is to fire the 

 charge is placed in a boat close to the tube; to the top of which a piece 

 of cord is attached, which he holds in his left hand. Having in the 

 boat a brazier, with small pieces of iron, red hot, he drops one of 

 them down the tube ; this immediately ignites the powder, and 

 blows up the rock. A small part of the tube next the cartridge is 

 destroyed, but the greater part which is held by the cord, is reserved 

 for future service. The workmen in the boat experience no shock; the 

 only effect is a violent ebullition in the water, arising from the explo- 

 sion; but those who stand on the shore, and upon any part of the rocks 

 connected with those blowing up, feel a very strong concussion. - The 

 only difference between the mode of blasting rock at Howth and at 

 Plymouth, is, that at the latter place they connect the tin pipes by a 

 cement of white lead. A certain depth of water is necessary for safety, 

 which should not be less than from eight to ten feet. 



