A catalogue of stellar spectra, compiled at Harvard College Observatory. The work was made possible through funds donated by the widow of the pioneering astrophysicist Henry Draper 1837-82, and the catalogue was named as a memorial to him. Under the direction of Edward C. Pickering 1846-1919, Annie Jump Cannon 1863-1941 classified most of the 225,300 stars in the nine-volume catalogue between 1911 and 1915, though the first volume was not ready for publication until 1918 and the ninth did not appear until 1924. The Harvard spectral classification system adopted the sequence of classes still in use today - O, B, A, F, G, K and M. This apparently random order resulted from earlier work in which classes were originally named in alphabetical order. See also: spectral type.