Eventually, however, I evolved an explanation that, I feel sure, was very nearly correct. This was that the principle involved was an atomic or rather electronic flow between the radium ore and the green stone! In a way, perhaps, akin to the flow of electrons between the filament and the plate of a radio tube. That the sphere of green was held in place by this stream of invisible electrons that formed a solid band of waves--something like magnetic waves--and that the green material being polarized was forced to rotate. Each time it touched a rod, a current or wave of electrons rushed back to the active mineral in the column and allowed the sphere to move forward towards the next rod. It was in fact on the principle of an electric motor, the radioactive material representing the electricity, the sphere the rotating armature, the upright rods the brushes. What a power this would be to put at the disposal of civilized man! No power needed to generate the primary force. No appreciable loss of the basic energy. No frictional loss of power or wear and tear. In my imagination I could picture the world’s industries increased thousands of times, completely revolutionized by such a source of inexhaustible power. * * * * * I COULD visualize motor cars, ships, aircraft, trains speeding over land and sea and through the air without carrying fuel, with never a need of replenishing their power. I could see factories, mills, machinery of every kind operating without smoke, without waste. Grime, dust, ashes, coal and oil would be things of the past. It would be the greatest boon to mankind in the history of the world. And yet, unless I were vastly mistaken, it was an impossibility, a mere dream. Nohul Voh had told me that the green rock was extremely rare, that his sphere and a few small fragments were all of the mineral that existed as far as he knew, that these pieces had been handed down from father to son of his family for countless ages, and that their original source was unknown. Legend had it, however, that they were bits of a most sacred image that, in the very dawn of their history, had been worshipped by the first of the Kitche Mayas. Always, he declared, it had been credited with magical powers. Always, each sorcerer of his clan had prized it, guarded it; but only he had discovered its amazing properties. And probably, I thought, nowhere else but in this valley of Mictolan was there the peculiar radioactive mineral that was needed to produce the results. But even if it were visionary, it was fascinating to speculate upon its possibilities, and, with my mind filled with it, constantly dwelling upon it, I began to wonder if the Bridge of Light was not also a variation of the same force. I questioned Nohul Voh, but he could give me little information.