Albert A. Michelson
Early measurements

Michelson was fascinated by light all his life. Once asked why he studied light, he reputedly said, "because it's so much fun".

As early as 1869, while serving as an officer in the United States Navy, Michelson started planning a repeat of the rotating-mirror method of Léon Foucault for measuring the speed of light, using improved optics and a longer baseline. He conducted some preliminary measurements using largely improvised equipment in 1878, about the same time that his work came to the attention of Simon Newcomb, director of the Nautical Almanac Office who was already advanced in planning his own study.

Michelson's formal experiments took place in June and July 1879. He constructed a frame building along the north sea wall of the Naval Academy to house the machinery. Michelson published his result of 299,910 ± 50 km/s in 1879 before joining Newcomb in Washington DC to assist with his measurements there. Thus began a long professional collaboration and friendship between the two.

Simon Newcomb, with his more adequately funded project, obtained a value of 299,860 ± 30 km/s, just at the extreme edge of consistency with Michelson's. Michelson continued to "refine" his method and in 1883 published a measurement of 299,853 ± 60 km/s, rather closer to that of his mentor.
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