Friedrich Bessel
For ten years he actively participated in the work of the Astronomical Society, contributing papers on the theory of astronomical instruments, the aberration of light, the differential sextant, and the convertible pendulum. With Francis Baily he began in 1822 the construction of tables for the mean places of the fixed stars; the work was left uncompleted, because of the publication of the "Fundamenta Astronomiæ" of Friedrich Bessel. Their efforts, however, led to the complete catalogue of stars of the Royal Astronomical Society.