Frank stood on deck as the vessels steamed along, and could not help drawing a contrast between his present position and the one in which he was placed when he first saw Red River. Then, he and his companions were fugitives from a rebel prison; they had been tracked by bloodhounds, and followed by men at whose hands, if retaken, they could expect nothing but death. He remembered how his heart bounded with joy on the morning when he and his associates, in their leaky dug-out, had arrived in sight of the Mississippi. Then, he was ragged, hatless, and almost shoeless, weary with watching, and living in constant fear of recapture. Now, he was among friends, the Old Flag waved above him, and he was the second in command of one of the finest vessels in the squadron. The passage up the river was without incident worthy of note, and in a short time they arrived at the obstructions which the rebels had placed in the river nine miles below Fort De Russy. A vast amount of time and labor had been expended upon these obstructions, but they were speedily cleared away, and the fleet passed on. They had expected a stubborn resistance at the fort, but it had been captured by the army after a short engagement, and the gun-boats kept on to Alexandria. CHAPTER VI. Frank turns Detective. A day or two after the arrival of the fleet at Alexandria, it became known that several persons belonging to the rebel secret service were hovering about in the vicinity of the village, with the intention of destroying some of the vessels by torpedoes--contrivances made to resemble pieces of coal--which were to be placed in those barges out of which the boats were supplied with fuel. By some means the names of these persons became known to the admiral, who issued a general order, calling on all the officers of the squadron to kill or capture them wherever found. The same day the order was issued Frank obtained shore liberty, and while roaming about the town, espied a name on a sign that immediately attracted his attention. It was one of the names borne in the general order. "There's one of the rascals, now," soliloquized Frank, "or, rather, where he has been. I wonder where he is. I'll see if I can't find out something about him. If he could be caught, he would be put in a place where he wouldn't lay any more plans to blow up Union gun-boats." The sign which had attracted his attention bore the name and occupation of the individual in question--"S. W. ABBOTT, Chemist." The store had been closed on the approach of the Union forces, and was now in the possession of several army surgeons and their assistants, who were overhauling its contents, and appropriating whatever they thought might be of service to them. A negro was leaning against the counter, and of him Frank inquired-- "Boy, do you belong here?" "No, sar," he answered, indignantly; "I 'longs nowhar. I'se a free man, I is. I'se a soger." "Never been in this town before?" "No, sar."