After finding they were fairly under way, Frank, accompanied by Archie, went into the cabin, and sat down to collect his thoughts, for, in the excitement of his unexpected promotion, he moved like one in a dream. The cabin steward had already taken his trunk into his state-room, and was engaged in making his bed. Captain Nelson! How strangely it sounded; and Frank repeated it several times, and gazed about the cabin as if he could scarcely believe that he was awake. He read his appointment and orders over and over again, both to fully understand what was required of him, and to convince himself that he was in reality the commander of a vessel. When he was made the executive officer of the very boat he now commanded, he had reached the height of his ambition, and his present position was a step higher than he had dared to look. The captain of a gun-boat generally lives in a little world of his own. He has a cabin all to himself, messes alone, and rarely has intercourse with his officers, except upon business. If he has a messmate, it is either a clerk, or the paymaster or doctor of the vessel. Frank was not entitled to a clerk, but he had a paymaster, and, at his request, Archie at once commenced the removal of his baggage into one of the vacant state-rooms in the cabin. While thus engaged, the orderly announced the executive officer, who entered to inquire if Frank had any orders to give. The latter replied that he had not, and for nearly an hour he remained in conversation with the executive, during which he learned the exact state of affairs about decks. Every thing appeared to be going on smoothly, and Frank had no desire to show his authority by issuing unnecessary orders. One by one the wardroom and steerage officers came in to congratulate the young commander, and when bed-time came they returned to their quarters, saying among themselves that "Captain Nelson didn't feel any bigger in his new position than he would if he were nothing but a Johnny master's mate." One afternoon, after they had reached the Mississippi River, as Frank sat at his desk, writing a letter to his mother, and Archie lay on the sofa close by, engaged in reading, there was a commotion on deck, and the orderly burst into the cabin, exclaiming-- "Rebels, cap'n! A battery just ahead, sir!" And he had scarcely spoken, when there was a roar of cannon, and the shells burst over and about the vessels. "Call to quarters," said Frank, as he sprang to his feet and ran into his room after his side-arms and the keys to the magazine. The orderly disappeared, followed by Archie, who, throwing his book into the furthest corner of the cabin, ran on deck, without even waiting to get his hat. After ordering the executive, who met him at the door, to have the lamps in the magazine lighted, and to prepare for action, Frank ran into the pilothouse, and looking up the river, discovered a smoke arising from a point half a mile in advance of them.