Of All Possible Worlds — William Tenn

It was a good job and Max Alben knew whom he had to thank for it-his great-grandfather. "Good old Giovanni Albeni," he muttered as he hurried into the laboratory slightly ahead of the escorting technicians, all of them, despite the excitement of the moment, remembering to bob their heads deferentially at the half-dozen full-fleshed and hard-faced men lolling on the couches that had been set up around the time machine.