Booby Prize by George O. Smith

Peter got the paperweight and set the equipment going again just as Forsyth returned with a dozen dark sun-glasses in leather cases. He had bought the best that the finances of the vast Higgins holdings could get without having them made especially. He took one pair from Forsyth and looked at them before he put them on. They were the high-grade jobs with polished lenses set in gold-filled frames; they cost about fifteen dollars a pair, complete with leather case and a wisp of chamois to keep them clean. They were coated-glass, and fifteen dollars times twelve pair added up to a hundred and eighty bucks worth of what Higgins would have called 'petty cash'! And Peter could not even afford to take Norma Higgins dancing.

Peter Mansfield pressed the big button again and they watched the receiving end intently. Through the dark glasses, they saw the focal point of the receiver as a bright glow that (due to the retention of vision) made a small vertical square plane come into being, to move swiftly back across the table. It disappeared at the end of its traverse. And from the swift-moving plane of bright blue radiance there poured an ultra-fine silt.