"Now he's gone further from the window let's be moving along.

That plank ought to make it easy sledding for fellows like us." Indeed, it would be hard to find a couple of more athletic boys than Hugh and his chum.

Their intense love for every type of outdoor sport had kept them in splendid physical condition, so that their muscles were as firm as those of an athlete in training.

To make their way up that sloping board and reaching the open window was likely to prove a mere bit of child's play with such fellows.
Hugh was the first to ascend.

When he had raised himself so that he could peep over the window ledge and see within the building he apparently found the coast clear; for Thad, coming along just behind, received a gentle prod with a toe, twice repeated, which he knew to be a signal that all was well.
By the time Thad arrived the other was already well within the room, having slipped across the window-sill without making the slightest sound.