Dr. Albert A. Michelson, world-famous physicist, was in receipt of permission from the war department to use the Ross flying field of Pasadena, Cal., for his second experiment of measuring the speed of light. The application to use the field was filed by the Mount Wilson observatory at Pasadena.
A straight path, one-half mile long, is available on the field. The light will be reflected along the course by mirrors and timed. The resultant speed figure, besides being freer from error will serve as a check on previous values. By his latest test Dr. Michelson hopes to achieve a result in which the probable error is reduced to one part in a million.
The plans of the University of Chi- (Continued on Page 4)
A rotating prism-operated by an air turbine and timed by a vibrating tuning fork-and a series of mirrors will cast the beam of light over the accurately measured course. Because the pipe will be evacuated the errors due to air resistance are expected to be eliminated.
The prismatic mirror will be eight-sided. When its rotation is such that the image of the light beam, traveling to the end of the pipe, cast back to one of the facets and over to the eye of the physicist, is stationary the ray’s velocity can be calculated from the speed at which the mirror is whirling.
Two years ago, in a speed test made between Mount Wilson and Mount Old Baldy, Dr. Michelson determined that light in a vacuum traveled 186,284 miles a second. This mean value was held correct within one part in 100,000.
Help ensure Jewish news remains accessible to all. Your donation to the Jewish Telegraphic Agency powers the trusted journalism that has connected Jewish communities worldwide for more than 100 years. With your help, JTA can continue to deliver vital news and insights. Donate today.
The Archive of the Jewish Telegraphic Agency includes articles published from 1923 to 2008. Archive stories reflect the journalistic standards and practices of the time they were published.
