Sperry Bright

Electricians were busy last week on the roof of a hotel in Charlottes ville, Va. Three miles away, across a valley, stood Monticello, old home of Thomas Jefferson. The electricians were adjusting a search light to play on Monticello, a searchlight so huge that were Mon ticello a mile nearer, the dazzling light would artificially "sunburn" a person standing on the old colonial porch at midwinter midnight. The special function for which the light was being got ready was a spectacle in honor of the Institute of Public Affairs which opened last week at the University of Virginia (see p. 24). Thereafter the searchlight, hugest in the world, would be at the service of Virginia physicists and of night flyers between Boston and New Orleans. Differing from bright predecessors only in size, the monster Monticello searchlight is the latest creation of Elmer Ambrose Sperry, inventor of gyroscopes, gyro-compasses, stabilizers, searchlights (TIME, March 30, 1925, Nov. 1, 1926). At Scott Field, Ill., there is a Sperry light which airmen have seen 150 miles away, through 40 miles of rain. The new light in Virginia is five times as large and bright as this biggest and brightest light in Illinois. When 17,200 watts of current are turned on, the crater of the new light's arc becomes the hottest spot on earth--38,000DEG Fahrenheit. Quartz prisms in the 62-inch globe absorb so much of this heat that the light, passing off with an intensity of 1,385,000,000 candle power,* will not blister the skin of persons keeping more than 1,000 feet distant. Engineers predicted that on clear nights the Monticello beam, if aimed vertically, would be visible to the naked eye 600 miles away. U. S. astronomers were advised not to suppose that the in creased luminosity of their horizon heralded the arrival of a new star or comet.

*Equivalent to 1/200 of the radiance of a fifth magnitude star (smallest size visible to the naked eye.