1910 The original telescope mounting was removed and replaced. 1915 Phillip Fox published The Annals of the Dearborn Observatory. 1920 Fox resigned and was replaced by Oliver Justin Lee. Lee continued the previous work of Fox which dealt with the proper motion and parallaxes of stars used in the study of galactic structure and rotation. Lee initiated a study of faint red stars. 1930 A wide-field camera with an objective prism was added to reveal the spectrum of each star in the field at the same time. This instrument was used for stellar spectral classification. 1931 Dearborn photographed the asteroid Eros, which contributed to improved accuracy of distances in the solar system. 1933 Dearborn participated in a combined effort to measure the continental drift.