Of course, they were compelled to obey; and, when they got out to the end of the plank over the water, the pirates lifted up their feet, and down went the prisoners; and they generally found their way to the bottom in a hurry.

I escaped by swimming.

I was in the water twenty-four hours, and was picked up by a vessel bound to New York." "I suppose you had a life-preserver," said Johnny.
"No, sir.

I had nothing to depend upon but my own exertions." "You must be some relation to a duck," said Archie, speaking before he thought.
"I suppose you mean to convey the idea that I am an excellent swimmer," said Arthur, turning around in his saddle, and looking sharply at Archie.
"Yes; that's what I intended to say," replied Archie, demurely.
"The vessel landed me in New York," continued Arthur, "and I went home; and, having become tired of wandering about, and our troubles with Algiers being settled, I led the quiet life of a student until the Florida war broke out, and then I enlisted in the army." "Now, then," thought Archie, who had been paying strict attention to all Arthur said, "I have got a basis for a calculation, and I am going to find out how old this new friend of ours is.

War was declared against Algeria (not Algiers) in March, 1815; and on the 30th day of June, in the same year, the Dey cried for quarter, and signed a treaty of peace.
If Arthur began his wanderings at eleven, and spent four years with Decatur, he must have been fifteen years old when the war closed.