Ray Meter

There is now a meter for measuring the intensity of ultraviolet rays. Its inventor, Dr. Harvey Clayton Rentschler (Ph. D.) director of lamp research for the Westinghouse Lamp Co., exhibited it last week at the annual meeting of the New York Electrical Society, as his inaugural demonstration upon assuming the Society's presidency.

Ultraviolet rays, whether from the sun or from mercury or carbon lamps, prevent and cure rickets, are valuable for general well being. But too much of them can cause deep burns and nervousness. They are suspected as the remote cause of other ailments. It has been impossible to measure the exact amount given off by their source (sun or lamps) and to manage their dosage.

Dr. Rentschler constructed a photo-electric cell with one pole made of uranium. Uranium is sensitive only to the ultraviolet rays of the spectrum. They charge it electrically. Hence when the Rentschler uranium bulb is exposed to an ultraviolet ray source an electric charge is created in proportion to the ray's intensity. This charge is accumulated in a condenser until a given potential is set up. Then the condenser discharges and, in the Rentschler meter, makes an argon tube give out a bluish flash and simultaneously causes a pencil to mark the occurrence on a chart. The time between the flashes and the tracings on the chart measures the strength of the ultraviolet rays.

Thus physicians may now administer ultraviolet rays in units the way they give other medicines by pellet, teaspoon, dropper. It remains for physicians to evolve a dosage scale in terms measurable by the Rentschler meter.