Before Northrop was an idol, a hideous thing on which frogs and snakes squatted and coiled.  It was a fitting piece to accompany the gruesome occupant of the little room in his long, last vigil.  In fact, it almost sent a shudder over me, and if I had been inclined to the superstitious, I should certainly have concluded that this was retribution for having disturbed the lares and penates of a dead race.

Doctor Bernardo was going over the material a second time.  By the look on his face, even I could guess that something was missing.

“What is it?” asked Craig, following the curator closely.

“Why,” he answered slowly, “there was an inscription—­we were looking at it earlier in the day—­on a small block of porphyry.  I don’t see it.”

He paused and went back to his search before we could ask him further what he thought the inscription was about.

I thought nothing myself at the time of his reticence, for Kennedy had gone over to a window back of Northrop and to the left.  It was fully twenty feet from the downward slope of the campus there, and, as he craned his neck out, he noted that the copper leader of the rain pipe ran past it a few feet away.

I, too, looked out.  A thick group of trees hid the window from the avenue beyond the campus wall, and below us, at a corner of the building, was a clump of rhododendrons.  As Craig bent over the sill, he whipped out a pocket lens.

A moment later he silently handed the glass to me.  As nearly as I could make out, there were five marks on the dust of the sill.

“Finger-prints!” I exclaimed.  “Some one has been clinging to the edge of the ledge.”

“In that case,” Craig observed quietly, “there would have been only four prints.”

I looked again, puzzled.  The prints were flat and well separated.

“No,” he added, “not finger-prints—­toe-prints.”

“Toe-prints?” I echoed.

Before he could reply, Craig had dashed out of the room, around, and under the window.  There, he was carefully going over the soft earth around the bushes below.

“What are you looking for?” I asked, joining him.

“Some one—­perhaps two—­has been here,” he remarked, almost under his breath.  “One, at least, has removed his shoes.  See those shoe-prints up to this point?  The print of a boot-heel in soft earth shows the position and contour of every nail head.  Bertillon has made a collection of such nails, certain types, sizes, and shapes used in certain boots, showing often what country the shoes came from.  Even the number and pattern are significant.  Some factories use a fixed number of nails and arrange them in a particular manner.  I have made my own collection of such prints in this country.  These were American shoes.  Perhaps the clue will not lead us anywhere, though, for I doubt whether it was an American foot.”

Kennedy continued to study the marks.