Edward Williams Morley (January 29, 1838 - February 24, 1923) was an American scientist and professor of chemistry. His most important work was in the field of physics and optics. In 1887 he began collaborating with and assisting the physicist Albert Michelson. They set up, executed, and improved their techniques many times in what is called the Michelson-Morley experiment. This involved making accurate measurements of the speed of light in various directions, and at different times of the year as the Earth revolved in its orbit around the Sun. These measurements were created to measure the differences in the speed of light in different directions. The results of their experiments supported Albert Einstein's strong postulate in 1905 that the speed of light is a constant in all inertial frames of reference for his Special Theory of Relativity. Morley's research on the atomic weight of oxygen was recognized as a National Historic Chemical Landmark by the American Chemical Society in 1995. He was the president of the American Association for the Advancement of Science in 1895, and he was the president of the American Chemical Society in 1899. Morley was awarded the Davy Medal, named for the great British chemist Sir Humphry Davy, by the Royal Society of London, England in 1907, and he also won the Elliott Cresson Medal, awarded by the Franklin Institute of Pennsylvania, in 1912, for important contributions to the science of chemistry. He died in 1923 at the age of 85.