Unfortunately I brought back no samples of the other materials I had seen in the valley, and there were only my observations and descriptions of the various phenomena to aid in formulating theories and hypotheses. I had assumed that the Bridge of Light was a jet of vapor or gas ionized by contact with radium or some radioactive mineral. But neither Dr. Farrabee, Professor Le Conte nor Sir William Lille agree with me. They are unanimous in declaring that, in their opinions, the vapor was in itself sufficiently solid to support the weight of human beings. At first this sounds incredible, for we invariably think of vapors or gases as thin, fluid and incapable of supporting solid objects. But it must be borne in mind that the terms “fluid” and “solid” are relative only. In comparison with air or helium gas, water is a “solid.” In comparison with water, mercury is a “solid.” Air will not support wood, but water will; water will not support iron, but mercury will. Conversely, compared to iron, mercury is a liquid; compared to wood, water is a liquid. And whether or not any material--so-called fluid or liquid--will support a given object depends entirely upon the relative weight--per cubic inch--of the two. Hence, if we can imagine a gas or vapor weighing more per cubic inch than a human body, that gas would support a man. And there is no scientific or other reason why there should not be gases heavy enough to do so; why there should not be gases as much heavier than water as helium or hydrogen gas is lighter than water. That the Bridge of Light glowed in various colors was perhaps (these eminent scientists admit) caused by radioactive minerals. In fact, such a stream of vapor, undoubtedly containing metallic elements or particles, if passing through rock containing Nohulite, would almost certainly glow with the various colors of the metallic elements produced by the Nohulite rays. Also, the scientists I have mentioned, as well as Professor Nordstrom, the world renowned authority on rare earths, seem to be fairly well convinced that Nohul Voh’s light (as well as the various other lights of Mictolan) was produced by a use of the same remarkable Nohulite. Dr. Farrabee’s experiments, as I have said, have proved that each metal, and metallic salt or solution, produces a distinct color under the Nohulite action. But so far he has been unable to find a single known metal that reacts with a white glow. The nearest he has come to this is by the use of a mixture of thorium and potassium. This gives a very brilliant but soft yellow light. Indeed, if any considerable quantity of Nohulite were available, had I in fact brought out a few hundred pounds of the material, I would have been a multimillionaire, and the artificial lighting systems of the world would have been revolutionized. So remarkable are the properties of the mineral, so insignificant its loss of energy that, ever since I have returned from Mictolan--and Dr.