is hands
and knees to follow up the scratch. He did not notice the discomfort of
his position, his eyes shone in excitement and a deep flush glowed in
his cheeks. Also, he began to whistle softly.

Joseph Muller, the bloodhound of the Austrian police, had found a clue,
a clue that soon would bring him to the trail he was seeking. He did not
know yet what he could do with his clue. But this much he knew; sooner
or later this scratch in the floor would lead him to the murderer. The
trail might be long and devious; but he would follow it and at its end
would be success. He knew that this scratch had been made after the
murder was committed; this was proved by the blood that marked its
beginning. And it could not have been made by any of those who entered
the room during the day because by that time the blood had dried. This
strange streak in the floor, with its weird curves and spirals, could
have been made only by the murderer. But how? With what instrument?
There was the riddle which must be solved.

And now Muller, making another careful examination of the floor, found
something else. It was something that might be utterly unimportant or
might be of great value. It was a tiny bit of hardened lacquer which he
found on the floor beside one of the legs of the desk. It was rounded
out, with sharp edges, and coloured grey with a tiny zigzag of yellow
on its surface. Muller lifted it carefully and looked at it keenly.
This tiny bit of lacquer had evidently been knocked off from some convex
object, but it was impossible to tell at the moment just what sort of an
object it might have been. There are so many different things which are
customarily covered with lacquer. However, further examination brought
him down to a narrower range of subjects. For on the inside of the
lacquer he found a shred of reddish wood fibre. It must have been a
wooden object, therefore, from which the lacquer came, and the wood had
been of reddish tinge.

Muller pondered the matter for a little while longer. Then he placed his
discovery carefully in the pastor's emptied tobacco-box, and dropped
the box in his own pocket. He closed the window and the door to the
dining-room, lit a lamp, and entered the passageway leading to the
vestry. It was a short passageway, scarcely more than a dozen paces
long.

The walls were whitewashed, the floor tiled and the entire passage shone
in neatness. Muller held the light of his lamp to every inch of it, but
there