P.S.--Should you meet with disaster, you will, as a last resort, destroy the steam machinery, and, if possible, to escape, set fire to your gunboat, or sink her, and prevent her falling into the hands of the rebels. The night selected--April 4--was rainy and of inky blackness, relieved by vivid flashes of lightning. No precaution that could be thought of was neglected. Chains were twisted around the pilot-house and other vulnerable parts, and wood was piled against the boilers, with which the hose was connected, to make the jets of steam available to repel boarders. On one side was lashed a boat loaded with pressed hay, while a barge of coal was fastened on the side furthest from the dangerous batteries, and the escape steam was led into the paddle-wheel house in order to muffle the sound. Among the fully armed crew were twenty of the most expert sharpshooters in the army. It was about ten o'clock when the _Carondelet_ swung round in the stream and started on its fearful race. The fleet fairly held its breath, as officers and men listened and peered down the river in the tempestuous darkness. Now and then the zigzagging lightning gave a momentary glimpse of the craft moving away, but the straining eye and ear caught no sight or sound. But when the _Carondelet_ was close to the batteries a blaze suddenly shot up several feet above the chimneys. The soot had caught fire and the reflection was thrown far out on the water. The engineer immediately opened the flue caps and all was darkness again. So quickly did this singular glow come and vanish that it must have been mistaken by the sentinels for a part of the lightning display, for it caused no alarm; but the turning of the escape steam into the paddle-box had allowed the soot to get dry, and they flamed up a second time. Though extinguished as promptly as before, the sentinels knew something was wrong and signalled to the batteries below that one of the boats of the enemy was approaching. It was useless to attempt concealment any longer. Walke ordered the engine ahead at full speed and ran close to the shore nearest the batteries, that their shot might pass over him. Aside from the enemy, this was dangerous work, for there was no telling into what obstruction the boat would dash. A man stood at the front with lead and line, quietly calling out in a guarded voice the soundings, which were repeated by a second man on deck, who forwarded the report aft to Walke, standing beside the pilot. All the time the rain was falling in torrents. Suddenly a dazzling gleam showed the pilot he was speeding straight for a shoal under the guns of the Confederate battery.