1166 The Galvanic Battery. [No. 108. 



of an inch deep, cut on its opposite sides. These grooves c. are then 

 partially filled, either with common sealing wax or dammer, and 

 the priming wires, previously heated, are made to bury themselves in 

 this. The wax being again softened, a strip of wood is to be forced into 

 each groove over the wire, and every aperture through which the water 

 could force its way, is thus closed. The plug having its inlaid wires con- 

 nected by the igniting wire, and having a small cartridge attached, must 

 then be driven into the collar of the case, and it only remains to con- 

 nect the priming wires with the main conductors, lower the charge into 

 the blast hole, and complete the circuit. An arrangement like the pre- 

 ceding was employed in an attempt to fire a charge of powder at the 

 bottom of an artesian well in Fort William, and although the pressure of 

 the water was so great that case after case was burst, yet on no occasion 

 could it be discovered that the water had reached the charge through 

 the plug. A coating of sealing wax, and a tin cap, protected the 

 exterior end of the plug, and prevented the water from passing through 

 the pores of the wood, but this was rendered necessary only by the 

 great depth of water, which was nearly 480 feet. 



In some operations, as those for deepening the Pambaum Passage, 

 [Fig. X.] common quart bottles have been used to contain the charges, 

 and when the depth is moderate, I have found, by a great many experi- 

 ments, that if the priming wires in these are carefully passed through 

 good corks, driven home and coated exteriorly with water-proof com- 

 position, the Battery seldom fails to insure their explosion. 



Section VI Of the Application of the Galvanic Battery in Opera- 

 tions for removing Sunken Vessels from the Channels of Rivers^ 



^c. ^e. 



The great value of the Galvanic Battery as an addition to the 

 resources of the engineer, has in no instance been so fully demon- 

 strated as in operations for removing the wrecks of vessels from the 

 channels of navigable rivers, &c. Every one who has obtained his 

 experience from actual practice in such operations, will be ready to 

 bear testimony to the uncertaint}^ the danger, and the expense of the 

 arrangements previously necessary for effecting the ignition of the 



