"Just wait a minute, and you'll see. You know as well as I do, Dunbar, photographs taken in infra-red light will reveal clear details through a mist. Why must the human eye be blind where the camera can see? It is all a question of securing the proper adaptation to etheric vibrations--which I have done by means of invisible rays produced by electrical action on certain iridium and osmium salts in these tubes." * * * * * Dunbar grunted a half coherent reply, and threw open the roof-door. As they came out into the heavy mist-laden air of the late July afternoon, the humidity rolled from them visibly. There was a peculiar stagnation in the atmosphere, as though the very breath of heaven had been congealed. Featureless gray clouds hung wearily over the landscape; a dull, blank haze obscured everything beyond a few hundred yards. One might have said that the very elements had gone to sleep. "Goodness, I do wish we could get some relief from this atrocious heat!" sighed Eleanor. "The twenty-ninth continuous day of it, unless I've missed my count!" grumbled Dunbar, as he mopped his perspiring brow. "Doesn't it beat the devil? What's more, it's getting worse!" "Yes, and the strangest thing of all is, it seems to affect the whole world!" returned the girl. "I just can't believe it's not something more than common weather!" "Hate to tell you what I suspect it is!" returned Dunbar, ominously. "Come, come, folks, what are you so cheerful about, all of a sudden?" Gates demanded, as he examined the adjustments of the wires. "Good heavens! I'm sick and tired of hearing there's something supernatural about a heat spell, just because it happens to be unusually prolonged." "Yes, but the other phenomena!" broke in Dunbar, his sharp eyes glinting with hostility. "The dust clouds--the checking of normal wind movements--the indefinable thickening in the atmosphere--the thunder storms of unprecedented violence--" "Nothing has been definitely established," denied Gates. "Personally, I doubt if it's anything at all, aside from a cycle of exceptional sun-spot activity. But we're wasting our time. Ready now for the infra-red eye?" "I'm all keyed up!" announced Eleanor, casting the young man one of her strangely kindled, animated glances. "Here, you make the first test," he decided, thrusting the black instrument into her hands. "Just fit it to your eyes like binoculars. Turn that screw for the adjustment. Wait! I'll see to the current!" He switched a lever, drew back a panel, and pressed a button. But, aside from a faint whirring sound, there was no apparent effect. "Now focus the instrument!" he went on. "Point it anywhere. If you don't see through that haze as easily as a knife cuts butter, then set me down as a fraud and a liar!" The girl screwed up her eyes. Faint wrinkles were visible on her broad, creamy white brow. A second passed in silence. Then an astonishing change overcame her countenance.