UNSEEN RAY AS GUARD

Sun (Auckland), Volume IV, Issue 1005, 23 June 1930, Page 12

UNSEEN RAY AS GUARD

AMERICAN INVENTION TO PROTECT JEWELLERS A 50-dollar bill guarded by an invisible ray was offered in February in New York to any person who could pick up the money without making the ray sound an alarm. The ray was set up at a meeting of the New York Illuminating Engineering Society in the Westinghouse Lighting Institute by James L. McCoy, research engineer of the Westinghouse Lamp Company. It was announced that the money would remain indefinitely behind the ray awaiting all comers, or until someone solved the riddle. The bill was put in a five-foot safe with the door closed, but unlocked. Somewhere athwart the safe, probably across the door, an ultra-violet ray was placed. It is harmless. It cannot be felt by human touch. It is invisible either in darkness or light. It "shines,” so to speak, upon a photoelectric eye some distance away. Anyone attempting to pick up the bill interrupts the ray, thereby casting an unseen “shadow” upon the mechanical eye. Thereupon the eye loudly goes "bing,” ringing a burglar alarm. Having introduced the merits of his invisible detective, Mr. McCoy proceeded to suggest fallibilities by demonstrating how other kinds of rays may be fooled. First he used a plain, honest light ray. While one hand, picking up the bill, interrupted this ray, McCoy with the other hand turned a flashlight upon "bing,” the photo-electric eye. The dumb eye mistook the flash for the same light as the detective ray and kept quiet. Next Mr. McCoy employed an invisible, infra-red ray. This time he kept “bing” quiet bv holding an ordinary lamp in front of the eye while extracting the money. Infra-red is near-heat, and an ordinary lamp produces enough of it to fool an electric eye. “But,” said McCoy, "you cannot fool an ultra-violet ray so readily, because of inability to produce the ultra-violet radiation. “With these rays it will be possible for jewellers, bankers and other custodians to add greatly to the security of their valuables. It can be made impossible for an intruder to move about without detection, as the rays can be placed at various angles in a room. They may operate a tear-gas barrage, or set off a silent alarm. They can be projected far enough to protect the entire mouth of a harbour in war time with a warning signal belt.”