Mannheim Observatory
The French thinker Voltaire was a frequent visitor to his Court, the Elector made numerous reforms during his reign and founded scientific institutions.
Mayer observed the Transit of Venus across the Sun on 6 June 1761 from a temporary Observatory built of wood by Karl Theodor in the Orangery in the park of Schwetzingen Castle.
The observations convinced the elector as early as July to begin work on an observatory building on the palace roof, which was inaugurated in 1764.
Carl Theodor and a visitor, Prince Franz Xavier of Saxony, wished to observe the phenomenon, but were unsuccessful due to bad weather.
In the following years, Mayer acquired numerous instruments, and with the help of books delivered from the Electoral Library made the Mannheim Observatory into an internationally known research facility.
In the visitors' book of the Mannheim observatory not only are there entries by many well-known colleagues, but also illustrious guests such as Wolfgang Amadeus Mozart, Benjamin Franklin, Envoy of the young United States, and even Arabic and other writings.
Barry's initial successes were undone by the wars of the Napoleonic Era during which severe damage was inflicted on the Observatory.
Famous astronomers were not retained, such as Heinrich Christian Schumacher (Director 1813–1815), founder of the oldest existing journal of astronomy, Astronomische Nachrichten, and of the Altona Observatory.
Friedrich Wilhelm Struve, founder and first director of Pulkovo Observatory at St. Petersburg, despite being interested was deterred by clumsy personnel policy.
In his time, amongst other things, a three-stage refracting telescope was purchased from Fraunhofer, which was later used by the German expeditions of 1874 and 1882 to observe the Transit of Venus.
Already mature plans for construction of a new observatory drawn up in the revolutionary period were no longer to be, and on 10 June 1850 it was decided to end the Institute by appointing no new Court Astronomer.
Plans to build a permanent observatory in Karlsruhe did not become a reality, very much to Valentine's annoyance, even though the first telescopes and instruments were purchased.
In 1892 a deputation of Heidelberg professors, amongst them Max Wolf, petitioned the Grand Duke of Karlsruhe for a University research and teaching observatory.
On 20 June 1898, the "Großherzogliche Bergsternwarte" at Königstuhl (the present day Heidelberg Observatory) was ceremonially inaugurated by Frederick I, Grand Duke of Baden.
Wolf worked on many areas of astrophysics, he investigated the structure of the Milky Way, star spectroscopy and gas nebula, and searched intensively for Asteroids, of which he discovered more than 800.
