  Startling though Grover’s statement that a man trained animals to be criminals was, it gave Roger the one link to build what he knew into a chain. Trained animals! That fitted in with claws on glass and made the rest of the puzzle fall into place. To Roger, it seemed clear that a clever animal trainer could teach his beasts to obey criminally intended orders just as well as make them do the ordinary tricks. What animal, he mused, would fit the conditions? A monkey came to mind as the logical sort. First of all, it was the one animal able to climb down a rope from the skylight on the roof, which it could have reached by being taken up the fire-escape on a candy factory next door, one story higher than Grover’s research laboratory. Coming down in that fashion, it could have been made to do a trick taught for the purpose—take the white rats, put them in a sack, and fix it to the rope—or the sack could already be at the end of the rope. Then, unaware that it had set off an alarm, it could have wandered about, doing such tricks as getting into the light beams, pulling the switch to “on” for the X-ray and the other electrical devices. Such an ape, too, with its master joining it during the time it wandered about, could have invaded Tip’s room, striking him with a huge paw, because it would be an ape; no smaller monkey could have reached down into the rats’ cage. “How will you trap him?” Roger asked. When his cousin outlined his plan, Roger was animated. “It might work,” he exclaimed, “He will turn out to be the one who brought the white rats. They were trained, too, maybe.” “I wondered that you did not see why I bought back issues of the newspapers,” Grover told him, “I had one idea that the thing might have been done by some zoo keeper; but the more possible notion was that some vaudeville act had trained animals. Now we do not need to comb through the advertisements of the theatre section. We know, by logical deduction, that we would find it.” Roger, and Potts, carrying out instructions about which they said nothing to any member of the staff, assembled a mass of materials, apparatus and paraphernalia. There were microphones; and they employed the laboratory’s device for producing infra-red rays, as well as a number of small cameras for taking motion pictures which Potts secured; to each one they applied a shutter-trip suggested by Grover, that would operate when a light-beam of the infra-red variety might be unknowingly broken by an intruder. Other parts, and wiring by the yard, they connected up. “But I don’t understand it,” Potts argued as they worked. “It’s all right to say a monkey climbed in through the skylight way; but how does that fit the snake-trail up the stairway?” “I asked about that,” Roger told him, “Cousin Grover was more in a joking humor than I ever saw him, and he said I’d done so well, he would leave that for me to work out, too.” “Did you?” “I think so, Tip. How’s this? Monkey comes in. No alarm on the skylight, because the magnetic plate under it would be ‘on’ all night and would have caught anybody—anything but a monkey able to jump at a command while it swung clear—or the man above swung it.” “So far, so good.” Potts waited expectantly. “The ape wandered around, until it heard a call it recognized from outside, on the street. It was trained to open bolts, and the only other bolt that wouldn’t have a camera equipment and electric plate was our coal chute, that had the Chief stumped how to fix it.” “And why would he have to go down there?” “To let in his mate—another beast.” “And what was it?” “Well, what could leave a snake trail?” “A boa-constrictor, or one of them bushmasters out of Australia?” “What else—out of Australia?” Potiphar stared, thinking hard. “I don’t know.” “Something that hops, and balances with its tail.” “A—you mean a—kangaroo?” Roger chuckled, nodding. “But why did they go to all that trouble, when a man could of swarmed down a rope, and got the rats?” “If he’d got caught—not knowing everything about the inside of our lab, maybe,” Roger responded, “He’d go to jail. But if we got a kangaroo, or an ape, the animal trainer could know it and have an ad. in next day’s papers, get back his animal that couldn’t tell what it was there for, and——” “Well, what was it here for? What made all that compulsatory?” “The motive made it compulsory, Tip.” “You didn’t tell me about any motive. Or how all this wire and stuff will catch anything when we don’t know anything will come tonight, like you hint at.” “The motive, Cousin Grover thinks, is to get into our safe, for our data and formula for synthetic camphor.” “Well, come to think—one nation practically controls the camphor gum output, and if they want to raise the price——” “Or forbid export to any other country, in war——” “I can see how much it would be worth to have what we developed for one client. Maybe some foreign nation wants the secret.” Tip was alert. His pale blue eyes and almost albino-white hair made him seem, usually, washed-out and not very bright. But with this thrilling possibility of intrigue and excitement brewing, he was as alert and intelligent as anyone could be. “We don’t know. But Cousin Grover thinks he will draw them on, and he publishes in the evening papers quite a write-up about the completion of the data. A friend, a newspaper fellow, will help us get it into good space.” “And so the Chief thinks this fellow with the ape and the mouses and the kangaroo is a criminal and made them criminals?” Roger nodded. They waited until the staff checked up with Grover all results from the day’s experiments, and departed. Doctor Ryder, assured that his rats were not a menace, left with the rest. Then, carrying from the doors, windows, coal-chute, skylight and all other available openings, wires from microphones set there, Roger and Potts led them all to a three-stage amplifier, having a delicately diaphragmed headset in circuit. With that headset on, if a heart beat within a foot of any mike, a drum-beat could be heard in the headset. Light-beams criss-crossed the entrances so that they must be interrupted by anybody or any thing that came along. Each was in circuit with one lamp of a number in a shadow-box, and the one that would stop glowing would show which beam had been broken. Thus prepared to be warned well in advance of any intrusion, Roger sat wearing the headset as he monitored the volume controls. Police hid inside and outside of the laboratory. The safe, bathed in invisible rays, was provided with a new form of “capacity” protection so that anybody or anything touching the metal and standing with feet on the floor, would form a circuit and overload a sensitive and delicately balanced radio tube, that would operate a relay, putting into the circuit a criss-crossed series of small water-hoses, two playing along each side of a square around the safe, not easily observed when inactive. And in that water would be an electric current strong enough to paralyze and chain, without permanently harming the invader! He could not avoid it, because the water must fall and no one, even aware what would happen, could dodge or avoid the spray and the stream. The precious, priceless synthetic camphor secret was protected. As he sat, knowing that in the dark around him were Doctor Ryder, Potts, and his cousin, Roger felt a little thrill of expectancy and uneasiness. Had he foreseen the outcome of the ruse, it is a question whether he would have danced for joy or shuddered in terror. The trap caught something unexpected. |
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