Edward Williams Morley (1838-1923), the American chemist and physicist. Morley's work in science is marked by a passion for 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 Michelson in their famous experiments to detect the 'ether drift'.