In the space between the keyholes and the green lights there were the letters and figures: A-1, B-2, C-3, D-4 ... and so on up to T-20.
Plainly it was the beginning of a complicated classification system with any number of combinations possible.
Behind the working man the row of cages partially hid the brooding horror of the place. There were twenty cages––and in each one was a sulking, red-eyed anthropoid ape. Plainly the fact that the number of apes coincided with the number of push-buttons, and with the number of keys, to say nothing of the red lights and the green lights, was no accident. The apes were sullenly silent, proof that they feared the man at the table so much that they were afraid to move.
At last the white-haired man stopped and breathed a sigh of satisfaction. Carefully he placed in the middle of the table the instrument which he had been examining. It looked like a slightly concave aluminum plate or tympanum, save that on the apex appeared a tiny ball of the same metal. Except for the color and the fact that the thing was almost flat, it looked like a small Manchu hat.
“Naka Machi!” said the man suddenly in a conversational tone of voice.
The chrome steel door swung open swiftly and silently and another man entered. He was about the same height as the first man, but he was younger and his eyes were blacker. His hair was as black as the wings of a crow. He was a Japanese dressed in Occidental garb.
“Naka Machi,” said the white-haired one again, “I have examined every bit of the infinitesimal mechanism in the ball on this tympanum. It is perfect. You are a genius, Naka Machi. There is only one genius greater––Professor Caleb Barter!”
Naka Machi bowed low, and as he spoke his breath hissed inwardly through his teeth after the Japanese manner of admitting humility––“that my humble breath may not blow upon you”––which never needed really to be sincere.
“I am merely a genius with my fingers, Professor Barter,” said Naka Machi in a musical voice. “The smaller the medium in which I work the happier I am, Professor; and in that I am a genius. But the plan for this so marvelous little radio-control, as you call it, came entirely from your head, my master. I did exactly as the plans bade me. Will it work?”