A refugee physicist modifies a penny weight scale at a gangster's casino so it tells the actual future of its customers.

"The scales aren't here anymore. Look Buster, I don't want any trouble. I run a nice quiet little place here, no rough stuff. I'm telling you -- the scales aren't here. You must be the twentieth guy this week that came in looking for those scales. But they're gone. Damn good thing, too, if you ask me."

Weird Tales (May 1950)
The Living Demons (1967)
Complete Stories of Robert Bloch -- V 1: Final Reckonings (1990)