Kennedy nodded and continued to examine the place where the
compartment had been jimmied. A low whistle aroused us: coming
over to the table, Craig tore a white sheet of paper off a pad
lying there and deposited a couple of small particles on it.

"I found them sticking on the jagged edges of the steel where it
had been forced," he said. Then he whipped out a pocket
magnifying-glass. "Not from a rubber glove," he commented half to
himself. "By Jove, one side of them shows lines that look as if
they were the lines on a person's fingers, and the other side is
perfectly smooth. There's not a chance of using them as a clue,
except--well, I didn't know criminals in America knew that
stunt."

"What stunt?"

"Why, you know how keen the new detectives are on the
finger-print system? Well, the first thing some of the up-to-date
criminals in Europe did was to wear rubber gloves so that they
would leave no prints. But you can't work very well with rubber
gloves. Last fall in Paris I heard of a fellow who had given the
police a lot of trouble. He never left a mark, or at least it was
no good if he did. He painted his hands lightly with a liquid
rubber which he had invented himself. It did all that rubber
gloves would do and yet left him the free use of his fingers with
practically the same keenness of touch. Fletcher, whatever is at
the bottom of this affair, I feel sure right now that you have to
deal with no ordinary criminal."