Suncatcher

Some of the sun's rays, speeding 93,000,000 mi. in eight minutes to Pasadena, Calif., darted last week into the world's most powerful sun-ray concentrator. Designed by Astronomer George Ellery Hale of Mt. Wilson Observatory, this "sun furnace" is 15 ft. long, has more than 30 lenses. When the rays reached the final focussing point, they were hot enough to melt a steel wire like an icicle in a frying pan.

Utilizing radiant energy from the sun is a dream that has harried many an experimenter. The sunshine falling in eight hours on a square mile in the tropics is equivalent to the energy stored in 7,400 tons of coal. The difficulty is to devise a sunshine catcher which is not expensive out of all proportion to the power produced. This is the defect of the commonest solar machines which have appeared so far--huge concave reflectors which focus on a boiler, make steam to drive small engines. One of the most optimistic U. S. experimenters, Dr. Charles Greeley Abbott of Smithsonian Institution, has invented a "sun cooker" with which he roasts meat, bakes bread. Two years ago Germany's Dr. Bruno Lange discovered a way of converting sunlight into electric current a hundredfold more efficiently than had been done before (TIME, Feb. 1 6, 1931). But to run a 300,000-kilowatt power station would require a square mile of Dr. Lange's silver selenide cells.

Commercial utilization of sunshine, however, is not the same thing as using sunshine to produce high temperatures for scientific research. Hottest heats obtained by any means have been less than 5,000DEG C. The California Institute of Technology, working with Dr. Hale's new sun furnace, expects to coax from it 6,000DEG--roughly the surface temperature of the sun itself.

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