Together we moved the laboratory table as he directed.
There, in the floor, concealed by the shadow, he had placed the same apparatus which I had seen him bury in the path between the Pearcy and Minturn estates at Stratfield.
We scarcely breathed.
“This,” he explained rapidly, “is what is known as a kinograph—the invention of Professor HeleShaw of London. It enables me to identify a person by his or her walk. Each of you as you entered this room has passed over this apparatus and has left a different mark on the paper which registers.”
For a moment he stopped, as if gathering strength for the final assault.
“Until late this afternoon I had this kinograph secreted at a certain place in Stratfield. Some one had tampered with the leaden water pipes and the electric light cable. Fearful that the lead poisoning brought on by electrolysis might not produce its result in the intended victim, that person took advantage of the new discoveries in electrolysis to complete that work by introducing the deadly strychnine during the very process of cure of the lead poisoning.”
He slapped down a copy of a newspaper. “In the news this morning I told just enough of what I had discovered and colored it in such a way that I was sure I would arouse apprehension. I did it because I wanted to make the criminal revisit the real scene of the crime. There was a double motive now—to remove the evidence and to check the spread of the poisoning.”
He reached over, tore off the paper with a quick, decisive motion, and laid it beside another strip, a little discolored by moisture, as though the damp earth had touched it.
“That person, alarmed lest something in the cleverly laid plot, might be discovered, went to a certain spot to remove the traces of the diabolical work which were hidden there. My kinograph shows the footsteps, shows as plainly as if I had been present, the exact person who tried to obliterate the evidence.”
An ashen pallor seemed to spread over the face of Miss Pearcy, as Kennedy shot out the words.