“I wish you particularly to notice these footmarks,” he said. “Do you observe anything noteworthy about them?”

“They belong,” I said, “to a child or a small woman.”

“Apart from their size, though. Is there nothing else?”

“They appear to be much as other footmarks.”

“Not at all. Look here! This is the print of a right foot in the dust. Now I make one with my naked foot beside it. What is the chief difference?”

“Your toes are all cramped together. The other print has each toe distinctly divided.”

“Quite so. That is the point. Bear that in mind. Now, would you kindly step over to that flap-window and smell the edge of the woodwork? I shall stay here, as I have this handkerchief in my hand.”

I did as he directed, and was instantly conscious of a strong tarry smell.