The instrument they unearthed was all that could be desired. "I believe," Marlin commented, "we can get this through by encasing it in a protective sheath." "How'll we get the sheath off?" "It can be done. We need a tube large enough to admit passage of the instrument. It can be just a rolled strip of sheet iron. We'll streamline it by welding the end to a point. When we've worked it through the mass far enough to project beyond the large pipe, we'll slide in the periscope. Last of all, we take a good solid rod, attach it to the rear projection of our sheath, and shove. When the sheath has cleared the top, it'll drop off, leaving the periscope head exposed." "Might work," DuChane acknowledged. "You've an ingenious mind. But we'd better wait until dark. Less chance of being observed by the august forces of law and order." "It'll be well along in the night before we've finished," returned Marlin. He caught hold of a door post as the sphere gave another shuddering lurch. * * * * * In their quest for material, they came upon Eli in the lower level of the superstructure. He was making adjustments throughout a bank of coils which seemed to constitute the major element of his apparatus. Pausing curiously, DuChane demanded: "What's that for?" Eli grunted, but the pride of an inventor won out over disdain. "You could not understand," he informed them ungraciously. "Locked in these coils is a power that will make the name of Elias Thornboldt outstanding in history. A magnetic field in which occurs such a stress as the atom has never known causes polarization of the repulsion plates below this floor which is--how can I express it--the opposite of magnetism, of attraction, of the force of gravity." "In other words," retorted DuChane, "anti-gravity." He nudged Marlin. "Professor Lamberton says your conclusions are unsound--that it would be impossible to build up a sufficiently strong magnetic field to accomplish the results you claim." "That nincompoop!" exploded the scientist. "That stuffed piece of shirt! What does he know about atomic stress? Nothing! Yet he presumes--" Eli paused suspiciously. "Who told you about Lamberton?" "Oh, we get around!" The bearded scientist snorted. "Why bandy words? To show up Lamberton in all his stupidity, I have only to do this--" With a dramatic gesture, he thrust home the prongs of a huge switch which occupied the central panel of a control board in front of the coils. Involuntarily, Marlin braced himself for a shock. Nothing happened. Nothing, at least, beyond a faint hum which emanated from the towering apparatus. "Well?" queried DuChane impudently.