Tom Swift and His Electronic Retroscope by Victor Appleton II Read Free Book Online Page A

Hutchcraft. "A carved surface means that different layers of rock are exposed at one time."
    "Exactly," said Tom. "For instance, if you carve a gouge in the rock, the cosmic radiation would penetrate deeper at that point than it would at an uncarved part of the rock. Therefore, as the cosmic rays penetrate a slight ways into the solid material, a sort of pattern is created inside the rock that follows the in-and-out depth pattern of the carvings on its surface."
    "Wait a minute!" Hutchcraft snapped his fingers in unimpressed sarcasm. "I think I get it. By measuring the pattern of penetration all through the rock, you can put together a picture of what the carving looked like before it was worn away."
    "That’s right, Mr. Hutchcraft," Tom said mildly. "Of course, the original cosmic rays are long gone, either absorbed or reflected back."
    "Then what remains to be measured?"
    "I’m getting to that. My device makes use of the natural magnetism in the rock to—"
    The archeologist held up an imperious hand. "Magnetism? You expect to find these inscriptions carved into magnetic rock?"
    "Not at all. Like most people, you may be under the impression that natural magnetism is only to be found in certain kinds of rock—lodestones, as they’re called. That’s true enough if you’re trying to produce a useful magnet, but it isn’t the whole story. All atoms, of any kind of material, possess magnetic properties; it’s a consequence of their internal configuration of electrical charges. They can be diamagnetic, weakly repelled by a magnetic field; paramagnetic, weakly attracted; or ferromagnetic, which produces the strong response we associate with standard magnets."
    "I understand," said Hutchcraft impatiently.
    "Ordinary rock, however pure, normally has traces of differing substances showing the whole range of magnetic properties. Most of these particles lie every which way, randomly, but a percentage magnetically arrange themselves with parallel or non-parallel orientations, which can be ‘flipped’ by a nanosecond’s exposure to a cosmic ray."
    "Then to anticipate you," the archaeologist interrupted, "I would suppose you to have a devilishly ingenious method that allows you to ‘read’ the general layout of these flipped particles. And from that you can derive the corresponding pattern of cosmic-ray penetration. And there’s your picture. That it?"
    Tom grinned. "Simple, isn’t it? Now, my camera here has two detectors. One scans the whole surface of the rock to probe out areas—called domains —of shared magnetic-dipole orientation; this gives us a baseline for comparison. The other uses a spectronic scanning beam to map out the quantized—"
    Hutchcraft suddenly slid onto his feet and stretched. "All very interesting, and now my curiosity is satisfied—in fact, saturated. I believe I’ll have a bite to eat." He turned his back on the young inventor and ambled out of the hut, leaving Tom with a disbelieving grin at the older man’s self-centered abruptness.
    Early the next day, before the humidity became too steamy, Tom trudged over to the grounded paraplane carrying the patching kit, Bud and Chow following. Wilson Hutchcraft, invited to watch as a courtesy, remained behind, saying he saw no reason to waste his energy unnecessarily.
    "Wa-aal, I’ll be a horned toad!" Chow grumbled under his breath.
    Arriving at the paraplane, Chow cast a critical eye on the rip in the liftbag. "Don’t look all that long t’ me, boss."
    Tom gave a wry smile. "It’s enough. Unfortunately the arrow struck right along one of the transifoil strips, and the bag tore a ways along the seam. Seems I didn’t ‘weld’ the pieces together as durably as I thought."
    "Which reminds me, genius boy," Bud remarked, "we still have no clue as to who shot that millionaire-arrow."
    "Got me an inkling," muttered Chow, eyes narrowed.
    Tom knew what he was thinking. "So far, Hutchcraft hasn’t been murderous," he pointed out; "just obnoxious." But