"Look here, Bob"--the professor swept all the papers aside with his hand. "You put it to them this way. Make them see this is not a prediction of the end of the world. We've had those before--nobody pays any attention to them, and rightly so. But this Mercutian Light is more than a theory--it's a fact. We fought it last November, and we'll have to fight it again next month. That's what I want to make them realize." "They'll think it is worth being serious about," Alan put in, "if one of those lights drop into Boston or New York--especially if it happens to play in a horizontal direction instead of vertical." We went into the whole subject thoroughly, and the professor gave me a second signed statement in which he called upon the nations of the world to prepare for the coming peril. The actual characteristics of the Mercutian Light we had discussed before several times. A good deal had been printed about it during the previous December--without, as I have said, attracting much public attention. The two meteors had been examined. They were found to be of a mineral that could have originated on Mercury. They were burned and pitted like other meteorites by their passage through the earth's atmosphere. Of the light itself Professor Newland had already given his opinion. It was, he said, some unknown form of etheric vibration. It radiated heat very slightly, but it had the peculiarity of generating intense heat in anything it touched directly. "You'd better explain that, father," said Beth, when we reached this point in our summary that evening. "Heat is the vibration of molecules of matter," the professor began. I nodded. "Make it clear when you write it up, Bob," Alan put in. "It's like this. All molecules are in motion--the faster the motion, the hotter the substance, and vice versa." "And this Mercutian Light," Beth added, "has the power of enormously increasing the molecular vibration of anything it comes in contact with--" "But it doesn't radiate much heat itself," Alan finished. Professor Newland smiled. "The old man doesn't have much of a show, does he?" Alan sat down somewhat abashed, but Beth remained standing beside her father, listening intently to everything he said. "This light I conceive to be the chief weapon of warfare of the Mercutians," the professor went on. "There has been some talk of those two meteors being signals. That's all nonsense. They were not signals--they were missiles. It was an act of aggression." I tried to get him to give some idea of what the inhabitants of Mercury might be like, for that was what my editor chiefly desired. At first he would say nothing along those lines.