(1797-1850), German banker and amateur astronomer

Wilhelm Beer was born in Berlin, Germany on 4 January 1797. Beer was a banker by profession; by avocation, however, he was an amateur astronomer and the owner of a private observatory made famous by the work of Johann Mädler.

Beer’s place in the history of astronomy is inseparably connected with the contributions that he and Mädler made between 1830 and 1840 to selenography and solar-system studies in general. Their first joint work was Physikalische Beobachtungen des Mars in der Erdnähe (1830), and their chef d’oeuvre was Mappa selenographica totam lunae hemisphaeram visibilem complectens (1836). This map, based on its author’s observations made at Beer’s private observatory with a Fraunhofer refractor of only 9.4-centimeter free aperture, constitutes a milestone in the development of selenographical literature. It was the first map to be divided into four quadrants (corresponding to a diameter of 97.5 centimeters for the apparent lunar disk) and contained a remarkably faithful representation of the moon’s face as it is visible through a 4-inch refractor. Its topographic structure was based on the positions of 105 fundamental points measured micrometrically by Beer and Mädler (and related to the previous measurements by Wilhelm Lohrmann).

Moreover, an accompanying volume, Der Mond nach seinen kosmischen und individuellen Verhältnissen, oder allgemeine vergleichende Selenographie (1837), contains the results of micrometric measurements of the diameters of 148 lunar craters and of the relative altitudes of 830 lunar mountains, determined by the shadow method. This book also contains a reduced version (to 32 centimeters) of the original map of 1836.

One more book appeared under the joint authorship of Beer and Mädler—Beiträge zur physischen Kenntniss der himmlichen Körper im Sonnensystem (1839)—before Mädler left Berlin to accept the professorship of astronomy and directorship of the astronomical observatory in Dorpat (now Tartu), Estonia. His departure ended the ten-year partnership with Beer.

For the remainder of his life Beer was unimportant in the history of astronomy. His name remains inseparably connected, however, with the best map of the moon produced in the first half of the nineteenth century. He died in Berlin on 27 March 1850.