"Mebbe so!" said Hank doggedly. "But it jest ain't logical. Life is chemical, an' existence is jest like a chemical equation, Jim--balanced on a hair-spring. Every little thing which happens: the fall of an empire, the discovery of a new element, somebody's cold in the head, anything an' everything, becomes a factor. We live in the world we live in today because it's the only possible world under the conditions of our past! "Of course, there could be--" Hank's eyes clouded. "There _could_ be--" I laughed at him. "For once, pal, you're caught in a middle. Your theory is just as good as Jamieson's, but no better. You can't prove it. So how about a couple rounds of checkers before we turn in?" Hank temporarily forgot whatever new conjecture had occurred to him. He looked a bit petulant as he aimed a shot of liquid brown at the distant bronze jug. "Now, looky here, Jim--you don't deny things would be a heap diff'rent if you an' me'd never met, an' I'd stayed home on my turnip farm?" "No." "Well, then!" "But," I pointed out, "perhaps it was ordained that we should meet and that you should come to Midland U." Hank groaned. "Jim Blakeson, you make me plumb sick! You're durn near as bad as Jamieson. That settles it! I began thinkin' this afternoon mebbe I'd do it; now I've made up my mind!" "Do what?" I demanded. "I'm gonna settle this question," he said firmly. "I'm goin' back to the past an' find out if you two are right. If things is inevitable, or whether circumstances can change 'em." I gulped. Hank sometimes said fantastic things but he never makes boasts he cannot fulfil. This, however-- "T--the past?" I faltered. "You heard me," declared Hank petulantly. "I guess I'll be kinda busy f'r the next couple o' days. I'm goin' to build me one o' them there now time-travel machines!" CHAPTER II Double Feature Well, you know me! Old brain-like-a-fish Blakeson. I stared at him foolishly for a moment, then, when he said no more about it, decided Hank had finally developed, along with his many other virtues, a sense of humor. So I chuckled, and he chuckled with me, and we went to bed a little while later, and I proceeded to forget all about it. It didn't even dawn on me, when the next morning he went out and came home with a couple armloads of wires, tubes and miscellaneous doogadgets, that he meant business. He was always prancing home with some kind of lab equipment or other--you know how amateur scientists are. So I went ahead with my duties, which were plugging the sale of U. S. Government Bonds and Stamps--and, by the way, you better buy 'em, kiddies!--and three days whisked by as days have a habit of doing. Then Travis Tomkins, chief technician of the observatory, halted me one day on the street. "Say, Blakeson, where's Cleaver hiding himself? He promised to help me plot the orbit on that new comet he and I discovered."