1158 The Galvanic Battery. [No. 108. 



intricate. Water, especially when holding saline matters in solution, 

 being a good conductor, its contact with the wires during the passage 

 of a galvanic current would tend much to diminish the igniting power 

 of this ; to prevent such an effect is therefore of primary importance in 

 the formation of conductors for sub-aqueous operations. Colonel 

 Pasley, to whose zeal practical science is so much indebted, has des- 

 cribed a very eifectual method for insuring the insulation of conducting 

 [Fig. III. a.] wires. In his plan "All inch new tarred rope of the 

 intended length of the conducting wires is passed slowly through boiling 

 Stockholm tar, which renders it impervious to water, — a necessary pro- 

 cess, or the rope on becoming wet after the wires are attached to it, as 

 described below, would shrink one foot in 100 feet, and draw the wires 

 into kinks." Two copper wires b. each 20 feet longer than the rope, 

 after being annealed, are separately coated with water-proof composi- 

 tion (made by melting 1 ib. of pitch, 2 oz. of bees' wax, and 2 oz. 

 of tallow together, taking care that it never boils) and are covered 

 with cotton tape, which is bound round the wire while the composition 

 is hot. The wires are then bound to the rope by strong packthread, c. 

 a turn being taken round each wire every time to prevent the 



d. possibility of their shifting. This being done, they are to be 

 bound round again with coarse tape IJ inch wide, after another 



e, coating of composition haS been laid on. Lastly, the whole must be 

 served with new tarred yarn, and again paid over with the composition, 

 when the process is complete. These arrangements, there can be no 

 doubt, would be most effective in preventing any water from reaching 

 the wires, but the resulting conductor is objectionable on account of its 

 very great weight, and the difficulty of managing it when its length is 

 considerable, especially in situations where strong tides and currents 

 [Fig. v.] are to be contended against. In a modification of this plan, 

 adopted in some experiments in Fort William, to be subsequently 

 detailed, the preceding objections were, to a considerable extent, 



a. removed. The rope and coatings with tape were entirely dis- 

 pensed with, the wires were each served with tarred rope yarn, over 



b. which a coat of dammer and grease was laid, the two wires were then 

 lashed together by rope yarn, another coat of composition applied, and 

 the conductor was complete. Five hundred feet of conductor, or one 

 thousand feet of wire were thus prepared, immersed in salt water. 



