In moments, the torch had cut a large disc of metal nearly free; seemingly on the verge of dropping into the safe. Now the flame left the safe, again retracting itself in that uncanny manner, no force seeming either to supply it with fuel or to support it thus, though it burned steadily, and worked rapidly and efficiently. Now, in mid-air, it hung for a second.
“I'm going to work the projector for a few moments by hand so that you may see this next bit of film.” Arcot moved a small switch and the machine blinked, giving a strange appearance to the seemingly solid images that were thrown on the screen.
The pictures seemed to show the flame slowly descending till it again touched the metal. The tungsto-iridium glowed briefly; then, as suddenly as the extinguishing of a light, the safe was gone! It had disappeared into thin air! Only the incandescence of the metal and the flame itself were visible.
“It seems the pirate has solved the secret of invisibility. No wonder the Air Guardsmen couldn't find him!” exclaimed Arcot, senior.
The projector had been stopped exactly on the first frame, showing the invisibility of the safe. Then Arcot backed it up.
“True, Dad,” he said, “but pay special attention to this next frame.”
Again there appeared a picture of the room, the window beyond, the mail clerk asleep at his desk, everything as before, except that where the safe had been, there was a shadowy, half visible safe, the metal glowing brightly. Beside it there was visible a shadowy man, holding the safe with a shadowy bar of some sort. And through both of them the frame of the window was perfectly visible, and, ironically, an Air Guardsman plane.
“It seems that for an instant his invisibility failed here. Probably it was the contact with the safe that caused it. What do you think, Dad?” asked Arcot, junior.
“It does seem reasonable. I can't see off-hand how his invisibility is even theoretically possible. Have you any ideas?”
“Well, Dad, I have, but I want to wait till tomorrow night to demonstrate them. Let's adjourn this meeting, if you can all come tomorrow.”