Editorial use only Edward Morely (1838-1923), American physicist and chemist. Morely is best known for his work on precise and accurate measurements. His early research was on the oxygen content of the air; his purpose was to test a meteorologist's theory of the atmosphere. From this he moved to a study of the relative atomic mass of oxygen, which he measured to within 1 in 10,000. (Only after his retirement was it known that such measurements represent the weighted average of the stable isotopes of the element concerned.) Lastly, he worked with American physicist Albert A. Michelson (1852-1931) in their famous experiments to detect the 'ether drift'. Photographed c. 1885.