“This soft loam,” he remarked, “yields beautifully clear impressions, and yesterday’s rain has made it perfect.”

We had not gone far when we perceived a set of footprints which I recognized, as did Thorndyke also, for he remarked:  “Miss Haldean—­running, and alone.”  Presently we met them again, crossing in the opposite direction, together with the prints of small shoes with very high heels.  “Mrs. Haldean on the track of her niece,” was Thorndyke’s comment; and a minute later we encountered them both again, accompanied by my own footprints.

“The boy does not seem to have crossed the path at all,” I remarked as we walked on, keeping off the track itself to avoid confusing the footprints.

“We shall know when we have examined the whole length,” replied Thorndyke, plodding on with his eyes on the ground.  “Ha! here is something new,” he added, stopping short and stooping down eagerly—­“a man with a thick stick—­a smallish man, rather lame.  Notice the difference between the two feet, and the peculiar way in which he uses his stick.  Yes, Jervis, there is a great deal to interest us in these footprints.  Do you notice anything very suggestive about them?”

“Nothing but what you have mentioned,” I replied.  “What do you mean?”

“Well, first there is the very singular character of the prints themselves, which we will consider presently.  You observe that this man came down the path, and at this point turned off into the wood; then he returned from the wood and went up the path again.  The imposition of the prints makes that clear.  But now look at the two sets of prints, and compare them.  Do you notice any difference?”

“The returning footprints seem more distinct—­better impressions.”

“Yes; they are noticeably deeper.  But there is something else.”  He produced a spring tape from his pocket, and took half a dozen measurements.  “You see,” he said, “the first set of footprints have a stride of twenty-one inches from heel to heel—­a short stride; but he is a smallish man, and lame; the returning ones have a stride of only nineteen and a half inches; hence the returning footprints are deeper than the others, and the steps are shorter.  What do you make of that?”

“It would suggest that he was carrying a burden when he returned,” I replied.

“Yes; and a heavy one, to make that difference in the depth.  I think I will get you to go and fetch Willett and the bicycles.”

I strode off down the path to the entrance, and, taking possession of Thorndyke’s machine, with its precious case of instruments, bade Willett follow with the other two.

When I returned, my colleague was standing with his hands behind him, gazing with intense preoccupation at the footprints.  He looked up sharply as we approached, and called out to us to keep off the path if possible.

“Stay here with the machines, Willett,” said he.  “You and I, Jervis, must go and see where our friend went to when he left the path, and what was the burden that he picked up.”