In any case, Professor Hadley’s apparatus took a splendid if incomprehensible form. We built it with elaborate care. And some two weeks before graduation it was finished. Professor Hadley was jubilant. Standing before us, he adjusted this and checked over that. He made sure of voltages and he measured micro-ohms of resistance. And then he got ready to turn it on.

For obvious reasons, I am not going to give you any clues to how it was made. As it turned out, this was the device by which I traveled to your century, and I wouldn’t want you to make another and come back to kill your fifty-two-times-removed-grandfather. You will want to, Charles, but it would be most improper. All the intervening generations, of which I am the revered sire, would never exist. Out of consideration for them I can’t allow it. My regards to your father, by the way, Charles. And your great-etc.-grandmother insists that I give you a message. She remembers you with an affection I cannot match, and hopes that you meet some nice girl and marry her and live happily ever after. I’m afraid I retain too much of my old antagonism toward Ginny’s first suitor to wish you well.

In re the family business, though, Professor Hadley struck an enthusiastic attitude. He made a speech, in which he said that his device would demonstrate the theoretically undemonstrable. Dramatically, he flipped the switch over.

He was right about demonstrating the undemonstrable, all right! He didn’t know his own genius or his own gadget. When he flipped over the switch a spark leaped, tubes lighted, insulation smoked…

And Professor Hadley, beaming, turned a rather pretty luminous puce color, and with every appearance of satisfaction faded quietly into thin air. Smiling happily and glowing like an off-color neon sign, he vanished deliberately before our eyes.