With the coming of such an insidious enemy their danger increased ten-fold, since by degrees it would add enough weight to the already heavily laden ship as to force it down all too speedily, with what hidden perils lying in wait below as only a lively imagination could vision.

Still that question remained unanswered—try as he might Perk seemed unable to successfully grapple with so puzzling and knotty a problem—if not a mail pilot off his course, nor yet some enemy trying to overtake, and run them down in midair, then who could it be?

With Perk bewildered the matter must inevitably settle down to one well practiced means for finding the answer to the enigma—“ask Jack—he knows”—a formula as simple as anything could be, also shifting all responsibility to other shoulders.

Perk went at it again, and asked for light.

“Mebbe naow, partner,” he called out, “it might be yeou guessed this crazy flier up yonder was some madcap pilot atryin’ to beat the record goin’ east from coast to coast; or else a locoed lad carryin’ a passenger who’d lose his hull fortune if so be he didn’t land in Wall Street inside so many hours.”

Jack laughed, as though amused at these vague stabs—he knew what the other had in his mind by going on in this fashion.

“Just fishing again, eh, Perk—want to know what I think covering the game, isn’t that so? Well, listen, and I’ll put a flea in your ear.”

“Go to it, partner—I’m agreeable, an’ wantin’ to be informed,” Perk hastened to say.

“Among those documents I examined there was one fact I laid some stress on, which consisted of a statement that the Secret Service man who sent his report in, and then seemed to disappear utterly from the knowledge of all men, declared it to be his opinion these hideout big guns in the criminal world, working under our old friend Slippery Slim Garrabrant, had some sort of an airship, with which they were doing a rattling good business—perhaps you slipped up on that particular fact; but I figured we might run across that plane, sooner or later, and have considerable bother with the same.”

“Hot-diggetty-dig! then Jack, you mean it could a been that crate we heard abeatin’ time on aour tail; an’ mebbe chasin’ us like hot beans—tell me, is that what hits you so hard, matey?”