Page:Popular Science Monthly Volume 89.djvu/529

 Harnessing the Sun

By W'aldeniar Kaempffert

���In the Sun Power Plant which Mr. Shuman erected at Maadi, near Cairo, Egypt, steam is generated by parabolic mirrors set in a light steel framework so as to throw the sun's rays upon a long trough through which water flows in a shallow stream. Thus steam is generated on the same principle applied in a greenhouse to prevent plants from freezing

��IF a boy can burn his name on a wooden bench with nothing but the aid of a convex lens and the sun's rays, why is it not possible to make the sun boil water, generate steam, and drive an engine? It seems absurd to burn coal costing from three dollars to thirty dollars a ton, depending upon your lati- tude and longitude, when the earth is deluged with heat.

The thought of using solar energy for generating power has occurred to many an engineer. John Kricsson, the in- ventor of the "Monitor," made more than one attempt to harness the sun. In his mind's eye he saw a desert tract nine thousand miles long and one hun- dred miles wide, extending from the Nor- thern coast of Africa as far as Mongolia, and great arid regions running from the southwestern part of the United Slates through Central America and along the coast of South America for a length of a

��thousand miles, animated with millions of throbbing engines deriving their power from the sun. On a rainless strip eight thousand miles long and one mile wide enough solar heat is wasted, he figured, to drive twenty-two million, three hundred thousand solar engines of one hundred horse-power each, nine hours a day. Why, he asked, why should not upper Egypt derive signal advantage from its fortunate desert location and attain a high social position because of its perpetual sunshine?

For thirteen years Ericsson worked with diligence born of optimism. Be- tween 1865 and 1878 he built no less than seven solar motors. Instead of a lens he employed mirrors, which were fastened on a movable frame and which concentrated the sun's rays on a boiler, when he was flriving his engine by steam, and on an air-chamber, when he employed a hot-air engine. Although he

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