While the soldiers were crowded together in the bomb-proofs to escape the flying bits of shell, the sailors on the little fleet of Confederate vessels anchored above them were busily engaged in getting ready a fire-raft which was to float down the river, and make havoc among the vessels of the Union fleet. Two such rafts were prepared; one of which, an immense affair, carrying cords of blazing pine-wood, was sent down in the early morning at a time when the vessels were utterly unprepared to defend themselves. Luckily it grounded on a sandbar, and burned and crackled away harmlessly until it was consumed. This warned Commander Porter of the danger in which his mortar-vessels were of a second attack of the same nature; and accordingly he put in readiness one hundred and fifty small boats with picked crews, and well supplied with axes and grapnels, whose duty it was to grapple any future rafts, and tow them into a harmless position. They did not have long to wait. At sundown that night, Commander Porter reviewed his little squadron of row-boats as they lay drawn up in line along the low marshy shores of the mighty river. The sun sank a glowing red ball beneath the line at which the blue waters of the gulf and the blue arch of heaven seemed to meet. The long southern twilight gradually deepened into a black, moonless night. The cries of frogs and seabirds, and the little flashes of the fireflies, were silenced and blotted out by the incessant roar and flash of the tremendous mortars that kept up their deadly work. Suddenly in the distance the sky grows red and lurid. "The fort is burning!" cry the men at the guns; but from the masthead comes the response, "No, the fire is on the river. It is another fire-raft." The alarm was instantly given to all the vessels of the fleet. Bright colored signal-lights blazed on the decks, and the dark, slender cordage stood out against the brilliant red and green fires that flickered strangely upon the dark wooded banks of the river. Rockets rushed high into the air, and, bursting, let fall a shower of party-colored lights that told the watchers far down the river that danger was to be expected. Then the signal-lights went out, and all was dark and silent save where the lurid glare of the great mass of fire could be seen floating in the great curves of the tortuous river toward the crowded ships. It was a time of intense suspense. The little flotilla of fire-boats, organized by Commander Porter that day, was on the alert; and the blue-jackets bent to their oars with a will, and soon had their boats ranged along a bend far above the fleet. Here they waited to catch the fiery monster, and save the ships. The danger came nearer fast. Rapidly the flames increased in volume, until the whole surrounding region was lighted up by the glare; while from the floating fire, a huge black column of smoke arose, and blended with the clouds that glowed as though they themselves were on fire. When the raft came into