Dr Abbot's Solar Oven

Lost tonnages of atomic helium plunge from the sun in every direction as radiant energy every second. Our earth, a kind of pinhead in space, intercepts only one two-billionths of the total solar output. This nevertheless equals, in three minutes' time, the United States' annual consumption of power from all sources. In other words, in a single hour the earth receives solar power equivalent to that produced by the burning of twenty-one billion tons of bituminous coal. Is it surprising that inventors have dreamed of ensnaring the sun's rays? Few projects have seemed so enticing...or have proved so disappointing.

The key to most failures to harness solar power lies mainly in the inefficiency of the devices. Energy rated at 1.5 horsepower per square yard arrives from the sun, but by the time it has passed to utilization its strength has dropped to 0.1 horsepower per square yard, or less. To utilize sun-power thus becomes a real problem. It must be focused, collected and stored, and all of these requirements have given trouble. For centuries men have experimented with the mirror to devise one whose magical curvature can trap enough of the fugitive beams to ensure an efficient concentration of solar heat. An early tradition, nearly as hoary as that of Apollo himself, tells of huge mirrors erected by the mathematician Archimedes to set the besieging Roman navy aflame at Syracuse in 212 B. C.

Like most of its successors, this legendary sun-machine was a failure; Syracuse fell to Rome, and the distinguished inventor was slain. Modern devices date from 1901, when the complicated Eneas "solar generator" was patented. Eight years later, Boyle and Willsie reported a sun-machine with a stationary mirror, a feature that practically guaranteed low heat of operation because of the oblique approach of the solar rays most of the time, and the low temperatures reached. Shortly before World War I, a group of enthusiasts organized Eastern Sun Power, Limited, and erected a plant on the banks of the Nile. Their idea was to capture sun-power for irrigation. The war interrupted this activity, and operations were never resumed. America's best-known helio-scientist is Dr. Charles G. Abbot, retired secretary of the Smithsonian Institution.

Analyzing his predecessors' failures, he spent a lifetime producing sun-mirrors of improved potential. By 1941, Dr. Abbot had raised the efficiency of solar devices to 15 per cent. With his solar oven, patented that year, one can bake bread or cook a dinner. Two years later, he announced that any western state-such as New Mexico-using machines of the "type now in existence," could furnish from solar radiation "more power than is now used for heat, light, transportation and manufacturing in the United States, and at a cost not perhaps exceeding the present cost of power from coal."