Read it through once

That afternoon they sallied out with borrowed 'credentials'—Tom's white shirt-collar, which he wore as a badge, and Huckleberry's rusty jack-knife, which served as a badge of office in its way. They called upon such citizens as they held in suspicion, interrogated them with a gravity that was comic to behold, and in the end arrived, by a series of fortunate blunders, at a clue which, to their excited minds, shone like a revelation.