152 MATTHEW FONTAINE MAURY 



cask, capable of floating it but anchored and held below 

 the surface from three to eight feet, according to the 

 state of the tide. The anchors of each are an 18-inch 

 shell and a piece of kentledge, so placed as to prevent 

 the barrels from fouling the buoy ropes at the change of 

 the tide. Each shell of a row is connected with the one 

 next to it by a stout rope thirty feet long and capable of 

 lifting it in case the cask be carried away. The casks are 

 water-tight, as are also the tanks, the electric cord enter- 

 ing through the same head. 



"The wire for the return current from the battery is 

 passed from shell to shell and along the connecting rope, 

 which lies at the bottom. The wire that passes from 

 cask to cask is stopped slack to the buoy rope from the 

 shell up to the cask, to which it is securely seized to 

 prevent any strain upon that part which enters the cask. 

 The return wire is stopped in like manner down along 

 the span to the next shell, as per the rough sketch. At 

 4 (in the sketch) the two cords are frapped together, 

 loaded with trace chains a fathom apart, and carried 

 ashore to the galvanic battery. 



"For batteries we have 21 Wollastons, each trough 

 containing eighteen pairs of plates, zinc and iron, ten 

 by twelve inches. The first range is called 1, the second 

 2, and the third 3, and the wires are so labeled. Thus 

 all of each range are exploded at once. 



"Besides these, there are two ranges of two tanks each, 

 planted opposite the battery at Chapin's Bluff. When 

 they were planted, it was not known that a battery was 

 to be erected below. These four tanks contain about 

 6,000 pounds of powder. The great freshet of last month 

 carried away the wires that were to operate the first 



