empt on
Vicksburg by that way.

In accordance with his orders, Walke, on arriving off the mouth of the
river, sent two light-draught gunboats, the Signal and Marmora, which
made a reconnoissance twenty miles up, where they fell in with a
number of torpedoes, one of which exploded near them. Having received
their report, Captain Walke determined, as the river was rising, to
send them up again with two of the heavy boats, the Cairo and
Pittsburg, to cover them while they lifted the torpedoes. The ram
Queen of the West also went with them.

These vessels left the main body at 8 A.M., December 12th. When the
torpedoes were reached they began removing them, the two
light-draughts in advance, the ram next, the two heavy boats bringing
up the rear. While thus engaged the Marmora began firing musketry, and
Lieutenant-Commander Selfridge, in the Cairo, pushed ahead to support
her. It was found that she was firing at an object floating in the
water, which turned out to be a torpedo that had already been
exploded. The Marmora was then ordered to proceed slowly again, the
Cairo following; but before the latter had gone her length two sharp
explosions occurred in quick succession, one under the bow and one
under the stern, the former so severe as to lift the guns from the
deck. The ship was at once shoved into the bank, and hawsers run out
to keep her from slipping off into deep water; but all was useless.
She filled and sank in twelve minutes, going down in a depth of six
fathoms, the tops of her chimneys alone remaining visible. The work of
destroying the torpedoes was continued after the accident, in which no
lives were lost. Thus, at the very beginning of operations, the
flotilla was deprived of one of its best vessels, the first to go of
the original seven.

The torpedoes by which the Cairo was sunk were merely demijohns filled
with powder and ignited by a common friction primer rigidly secured
inside. To the primer was fastened a wire passing through a
water-tight cork of gutta percha and plaster of Paris. The first very
primitive idea was to explode them by pulling from the shore, and it
is possible that the first to go off near the light-draughts was thus
fired. The matter was then taken in hand by a Confederate naval
officer, who arranged them in pairs, anchored twenty feet apart, the
wire leading from the primer of one to that of the other. Torpedoes
had hardly yet come to be looked on as a respectable mode of warfare,