Theodor Von Oppolzer

Born Oct. 26, 1841, in Prague; died Dec. 26, 1886, in Vienna. Austrian astronomer. Professor at the University of Vienna from 1875.

Oppolzer worked primarily on determining cometary and planetary orbits. He calculated the elements of 8,000 solar and 5,200 lunar eclipses from 1207 B.C. to A.D. 2163 and tabulated them in his Canon der Finsternisse. From 1873, Oppolzer directed work in Austria connected with the arc and angle measurements being made in Europe. He worked on the determination (with the help of telegraphy) of the longitudes of more than 40 locations. In 1884 he made the final determination of the acceleration of gravity, which served as the basis for the Vienna system of relative determinations of gravitational acceleration.