Michelson's 1879 determinations of the speed of light

In November of 1877 Albert Abraham Michelson (1852-1931), then a twenty-four year old ensign in the US Navy and an instructor in physics at the U.S. Naval Academy in Annapolis Maryland, hit upon the means to improve Foucault's rotating mirror approach. Even then, he needed to conduct many preliminary studies before being confident of an improved value for the speed of light. In his own words ([39] page 115) ``Between this time and March of the following year a number of preliminary experiments were performed in order to familiarize myself with the optical arrangements. Thus far the only apparatus used was such as could be adapted from the apparatus in the laboratory of the Naval Academy.''

In April 1878, he initiated contact with Professor Simon Newcomb (1835-1909) of the US Navy ([49] page 38) who was then superintendent of the navy's Nautical Almanac and renown in the navy and the scientific community as an astronomer. Michelson discussed his work and methods with Newcomb. At this point however, Michelson was still an unknown who would not be funded by the US Navy for such specialized research. Fortunately, having married Margaret McLean Heminway in the spring of 1877, he could turn to a wealthy father-in-law for financial support. His father-in-law²¹ had become deeply interested in Michelson's preliminary results and in July of 1878 provided him the $2000 necessary to purchase the fine optical instruments to carry out his measurements. So began a lifelong quest to determine the speed of light.