I felt that it might not have been exactly chivalrous, but it was necessary.
Cecilie's breast, which had showed a wildly beating heart as Kennedy told of how her mistress had died, was calmer now. Her air of surprise at the mention of the diamond was perfect. Elsa Hoffman was gazing at her, too, in tense interest. De Guerre was outwardly cool, Margot openly cynical, Preston leaning forward in ill-suppressed excitement.
For a moment Kennedy paused again, as if allowing all to collect themselves before he took them by assault.
"I have lately been studying," he remarked casually, "the experiments of Dr. Von Pfungen of Vienna showing the protective resistance of the human skin against an electric current. Normally, this resistance averages from seventy to eighty thousand ohms. In the morning, owing to the accumulation of waste products, the resistance may mount to almost double. In persons suffering from nervous anxiety, it decreases to five thousand and even down to a thousand ohms in cases of hysteria. Von Pfungen has also measured a human being's emotional feelings by the electric current. I have a copy of his instrument here. There is one person who sits gripping the carbon electric handle connected with this galvanometer who, to begin with, had a resistance of over sixty thousand. But when I began to tell of how Rawaruska met her death, of the hypothetical case I have built up by my observations and experiments here in this very laboratory, the needle of the galvanometer started to oscillate downward. It went down until it reached thirty-eight thousand at the mention of murder. When I said the case was perfect, it had got as low as under twenty thousand, swinging lower and lower as the person saw hope depart!"
Kennedy was no longer paying any attention to the little instrument. As I followed him, I became more and more impatient. What was it he had discovered? Who was it?
"Preston," cried Kennedy, suddenly wheeling on the young doctor, "through your regard—honorable, I am sure—for Rawaruska you have let yourself be drawn into doing a little amateur detective work. Let me warn you. Instead of clearing up the case, you merely laid yourself open to suspicion. Fortunately the galvanometer absolves you. You should have known that Cecilie was only a tool. De Guerre, your black wallet, that all diamond dealers carry—thank you, Wade—that's it."
Kennedy had turned from Preston to Cecilie, then to De Guerre so suddenly that no one was prepared for the signal he gave to the customs officer.
Wade had covered the surprised dealer and was now emptying out the contents of the wallet.
There, on the table, gleaming in the light of the laboratory, lay a wonderful brilliant, some three hundred carats—perfect in its blazing crystalline orange beauty. There it lay, a jewel which might charm and arouse the cupidity of two hemispheres. It shone like a thing of life. Yet back of its orange fire lay a black tragedy.
Margot was on his feet instantly.