Captain Vinton was astonished.  He had already begun to have serious doubts that this could be the same mysterious vessel he had seen cruising about the islands the night before.  All at once, unexpectedly, his doubts were resolved into a certainty that it was not the same, for even while he was wondering, a strange thing happened: 

A long, low, gray shape, something like a built-for-speed tug-boat with a short funnel, darted into view from between two keys, and, crossing the wake of the revenue cutter, glided swiftly along the very course the Arrow had taken, heading back toward Snipe Point.  Before the sloop and the steamer had come within hailing distance of each other, the strange craft, not depending on the dying easterly wind, was well along the course, sending back—–­toward a trail of darker smoke.

CHAPTER II

A CONTRABAND CARGO

“Well, what d’you know about that?” queried Billy, easily relapsing into slang when the first few minutes’ surprise had worn off.

“Dunno much about it,” Captain Vinton answered in a somewhat gruff tone, “but it looks to me mighty like a filibuster’s craft, or p’rhaps a smuggler’s.”

At the word “filibuster,” the boys—–­figuratively speaking—–­pricked up their ears.

“What on earth can they be trying to smuggle?” was Hugh’s eager question, to which the captain replied promptly: 

“Arms,—–­leastways, cartridges or gunpowder.  They ain’t tryin’ to smuggle ’em into Fluridy, but out of it,” he explained.  “Some gang of raskils is buyin’ small quantities of war goods up state—–­or else from Cuby—–­totin’ ’em down the coast an’ through th’ Everglades, and gettin’ ’em aboard some steamboat like that one, and so away where they’ll do the most harm.  Get me?”

“Yes,” replied Alec, “but I never would have thought such tricks were possible in these days.”

“Boy, you can’t never tell what’s just possible or what ain’t, in these days,” gravely asserted Captain Vinton.  “All sorts o’ things is like to happen, and sometimes it’s durned hard to know just what’s goin’ on.  But if that’s any filibustin’ outfit, they’d better make tracks out o’ these waters as fast as they can lay beam to wind’ard.”

So saying, he shifted the helm again and bore away at an angle that would enable them to come close to the revenue cutter, now scarcely a quarter of a mile astern.  Lighter and lighter came the wind, slower glided the Arrow over the long heavy swells, nearer and nearer came the cutter, going at a steady, rapid rate.  Soon the two vessels were within hailing distance, and a megaphone call came across the water, clear and distinct: 

“Sloop, ahoy!  Can you understand?”

“Aye, aye!” called Vinton.

The five boys gathered around him, eager to hear the interchange of calls.  Even Dave rose and shambled over to the little group at the tiller.  On the other vessel they could now see a number of men in blue uniforms and one in a civilian’s suit of gray tweeds.