But the captain's smile was anything but one of disappointment.

"So it is, Jem, and suppose we put something in it?"

And as he spoke he took the parchment from his pocket and laid it carefully in the drawer.

Jem stared.

"This is a rum go, capt'n," he said, "to go and take all this 'ere trouble, in risking our necks and a running the chance o' meeting all sorts o' nasty things for the sake of putting a piece of paper in this old concern."

"My good Jem, don't worry yourself about what you cannot understand," retorted the captain. "Now go back, step by step, in the same footprints. Mind, go as slowly as you like, but make no more marks."

Jem obeyed, grumbling and wondering, but he was a little easier when he saw the next step in the captain's movements.

Carefully guarding against stepping into fresh places, he stooped down and shook from his dredger a regular and equal quantity of dust on to the handmarks and footprints which they had made.

Then Jem understood the use of the flour dredger.

Spot by spot the captain pursued his task until he had reached the window, against which Jem leaned, stolidly watching him.