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Relatively Small Reflector: The Boat owner who does not have radar can still tap the power of other ships' radar to enhance the safety of his or her vessel. This is done by installing a passive radar reflector—a simple and inexpensive device consisting of thin, lightweight metal sheets arranged in mutually perpendicular planes. The sheets may fold for storage, but must remain rigid with respect to each other when opened for use. This relatively small reflector (each metal surface is only about a square foot in area) provides a radar reflection almost as strong as that from a medium-size steel ship. Without a reflector, the echo from the fiberglass (or wooden) hull of a small craft is so weak as to be easily overlooked among the echoes from the waves.
With a passive reflector hoisted as high as possible, the operator of a small craft can be sure that his Boat will be detected on the radar screens of passing ships. Often Coast Guard or other rescue craft searching for a Boat in distress are radar-equipped; the use of a passive radar reflector greatly increases a small craft's chances of being quickly spotted.
The hologram recorded the comparison of the light waves from the reflector and those from the white target. Because both wave trains passed through the same atmosphere, the relationship between them was not affected. When the developed hologram was viewed in laser light, a rough silhouette of the man and his pipe was recognizable. Though a reflector cannot always be attached to objects to be photographed, the method might provide a means of photographing orbiting satellites and observing some detail.
George Ellery (1868-1938), American lomer, who planned and built four great icopes. Hale was born in Chicago on June 368. After graduating from the Massaehu-Institute of Technology in 1890, he re-to his small, privately owned observatory Chicago, where he conducted researches in ir spectroscopy and perfected the spectro-heliograph (1891). In 1892 the 24-year-old Hale ie the first director of the Yerkes Observa-', where he set up a 40-inch refracting tele-
that is still the largest of its kind. In 1903, Hale moved to Pasadena, Calif., founded the Mount Wilson Solar Observa-His work there led to the discovery, in I, of magnetic fields in sunspots. Hale also persuaded Andrew Carnegie to finance a 60-inch reflecting telescope on Mt. Wilson; but even before this giant was erected, in 1908, he began planning a 100-inch reflector, completed in 1917. then arranged for Rockefeller funding of a •inch reflector on Mt. Palomar. Completed in
it is now named for Hale.
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