of this
he connected his mines in James River, below the obstructions, with the
shore stations, which afterward destroyed the "Commodore Barney," and
later the "Commodore Jones," and with part enabled other Southern ports
to be similarly protected.

Of his James River torpedoes, Captain Maury thus reported to the
Secretary of the Navy:

Richmond, June 19th, 1862.

Sir,--The James River is mined with fifteen tanks below the Iron Battery
at Chaffin's Bluff. They are to be exploded by means of Electricity.
Four of the tanks contain 160 pounds of powder, the eleven other hold 70
pounds. All are made of boiler plate.

They are arranged in rows, as per diagram, those of each row being
thirty feet apart. Each tank is contained in a water-tight wooden 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 anchor to
each is an eighteen 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 next one 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 entering and returning 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 aslack 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 the buoy ropes to the shell, and then
along the span to the next shell. At 4 the two cords are rapped
together, loaded with trace chains a fathom apart and carried ashore to
the galvanic battery. For batteries we have 21 Wollastons, each trough
containing 18 pairs of plates, zinc and wire, 10 x 12 inches. The first
range is called 1: the second 2: the third 3, and the wires are so
labelled. Thus all of each range are exploded at once.

Besides these there are two ranges of two tanks each, planted opposite
the battery at Chaffin'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 freshets of last month carried away
the wires that were to operate the firs