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Historical Highlight
(by Don Nicholson)Almost every student of astronomy or physics knows that Mount Wilson was the scene of one of Albert A. Michelson's definitive experiments to measure the speed of light. A plaque and a few concrete piers near the dome of the 24-inch TIE telescope mark the site of the apparatus on Mount Wilson.
In preparation for this experiment, the U.S. Coast & Geodetic Survey measured the distance between Mount Wilson and Mount San Antonio (also known as Old Baldy), nearly 22 miles, with extreme accuracy. Baseline Road in eastern Los Angeles County is a reminder of that accomplishment. While I was too young at the time to appreciate the importance of Michelson's work, I have some very vivid memories of the event.
The process of checking out the equipment and making many measurements to ensure statistical accuracy took place over a period of two years, beginning in 1924. Measurements were usually made during the early night hours, and scattered illumination from the powerful Sperry arc lit the surrounding area for one or two hundred yards, or so it seemed to me. A blast of compressed air drove the rotating mirror, creating a deafening noise.
It is those residual aspects, not mentioned in textbooks, of the experiment that remain strongest in my memory. I do, though, have a hazy recollection of Michelson, or perhaps it was Pease, peering into the eyepiece as he adjusted the micrometer to bring the reflected image of the slit into view. Looking back on the experiment, it seems a bit crude by modern standards but, in its day, it was the epitome of ``high tech''.
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