"Very well, sir." Atterbury turned and groped his way through a doorway, and they passed first into what appeared to be a storage-battery room. Huge glass tanks filled with amber-coloured fluid, in which numerous parallel plates were supported, lined the walls from floor to ceiling.
An ammeter on the wall caught Bennie's attention. "Weston Direct Reading A. C. Ammeter," he read on the dial. Alternate current! What were they doing with an alternating current in the storage-battery room? His eyes followed the wires along the wall. Yes, they ran to the terminals of the battery. It dawned upon him that there might be something here undreamed of in electrical engineering—a storage battery for an alternating current!
The electrician closed a row of switches, brought the two polished brass spheres of the discharger within striking distance, and instantly a blinding current of sparks roared between the terminals. He had been right. This battery not only was charged by an alternating current, but delivered one of high potential. He peered into the cells, racking his brain for an explanation.
"Atterbury," said he meditatively, "did I ever tell you why they do that?"
"Yes," answered the man. "You—told me—once. The two metals—in the electrolyte—come down—on the plates—in alternate films—as—the current changes direction. But you never told me—what the electrolyte was—I don't suppose—you—would be willing to now, would you?"
"H'm," said Bennie, "some time, maybe."
But this cue was all that he required. A clever scheme! Pax had formed layers of molecular thickness of two different metals in alternation by the to-and-fro swing of his charging current. When the battery discharged the metals went into solution, each plate becoming alternately positive and negative. He wondered what Pax had used for an electrolyte that enabled him to get a metallic deposit at each electrode. And he wondered also why the metals did not alloy. But it would not do for him to linger too long over a mere detail of equipment. And he turned away to continue his tour of inspection, a tour which occupied most of the morning, and during which he found a well-stocked gallery and made himself a cup of coffee.[5]
But the more he learned about the mechanism of the Ring the greater became his misgivings about undertaking the return journey alone with Atterbury through the air. If they were to go, the start must be made within a few days, for the condenser held its charge but a comparatively short time, and its energy was necessary for starting the Ring. When freshly charged it supplied current for the thermic inductor for nearly three minutes, but the metallic films, deposited on the plates, dissolved slowly in the fluid, and after three or four days there remained only enough for a thirty-second run, hardly enough to lift the Ring from the earth. Once in the air, the downward blast from the tractor operated a turbine alternator mounted on a skeleton framework at the centre of the Ring, and the current supplied by this machine enabled the Ring to continue its flight indefinitely, or until the cylinder of uranium was completely disintegrated.
Yet to trek back over the route by which he had come appeared to be equally impossible. There was little likelihood that the two Indians would return; they were probably already thirty miles on their way back to the coast. If only he could get word to Thornton or some of those chaps at Washington they might send a relief expedition! But a ship would be weeks in getting to the coast, and how could he live in the meantime? There were provisions for only a few days in the Ring, and the storehouse in the valley had been wiped out of existence. Only an aeroplane could do the trick. And then he thought of Burke, his classmate—Burke who had devoted his life to heavier-than-air machines, and who, since his memorable flight across the Atlantic in the Stormy Petrol, had been a national hero. Burke could reach him in ten hours, but how could he reach Burke? In the heart of the frozen wilderness of Labrador he might as well be on another planet, as far as communication with the civilized world was concerned.
A burst of sunlight shot through the window and formed an oval patch on the floor at his feet. The weather was clearing. He went out upon the platform. Patches of blue sky appeared overhead. As he gazed disconsolately across the valley toward the tower, his eye caught the glisten of something high in the air. From the top of the wreckage five thin shining lines ran parallel across the sky and disappeared in a small cloud which hung low over the face of the cliff.