National Geographic : 1940 May
CHAMPION of Star- Gazers 4f *editahoase. * They're buildingan eight-story tele scope out at Mt. Palomar in California. Its mirror, as you probably know, is 200 inches across ... weighs 20 tons. This gigantic optical device has a seeing distance, in miles, of -- well, put down a 6 followed by 21 cyphers. Astronomers call that distance one billion light years. * But a telescope is a great deal more than a huge mirror. Twice the size of any existing telescope this one required a mounting of entirely new design. * Considerthe fantastic requirements: 500 tons of steel put together to tolerances as close as two one-millionths of an inch so rigid its 75 feet of length will not deflect more than seven hundredths of an inch so flexible it can throw off an earthquake shock-so mobile it can be moved by the force of your breath. That is what it takes for the mounting of this telescope. * And of the few concerns having re sources of men, plant and equipment even to think of such an undertaking, the Westinghouse Plant at South Philadelphia was given the nod-and went to work. * Itwaspioneeringofthe highest order -practical science guiding meticulous skill in a six million dollar project. Many of the problems were unique. For instance, the midday sun, beaming through sky lights, could expand a 154-ton bearing enough to upset fine calculations, so a giant "sunbonnet" had to be devised to shade the mounting during construction. * When ready for use this mounting will have three observation points-one will have an automatically self-leveling floor and spectrograph table. A fourth observation point beneath the floor will be air-conditioned and temperature-regulated. * And this entire 500 tons of mobile structure will actually be floated on oil, re quiring only 1/650,000 of a horsepower to sweep it across the skies-one flea power. We make small motors, but not that small, so a one-half horsepower mo tor will furnish the power. * This has been a thrilling task, even for a plant capable of turning out annually a million horsepower in turbines. The in conceivable exactions of the job, the mad combination of gigantic mass with split hair precision, imposed no unusual de mands, for our own products regularly called for just such extremes of size and accuracy. We feel an inward satisfaction in the knowledge that our standards gener ously encompass the decimal accuracy re quired by this champion of star-gazers. "Mention the Geographic-It identifies you."