  Christian Ludwig Gerling's 1817 appointment as Professor for Mathematics,
Physics and Astronomy resulted in the foundation of the Mathematical and
Physical Institute of the Philipps University. In 1838, Gerling moved onto new
premises in the main building of the former D\"ornberger Hof in Renthof Street
where the Philipps University's astronomical observatory was installed in the
upper part of the old tower in 1841. The most important device at that time was
a transit instrument which served to measure the transit times of stars in the
meridian. Precise alignment required the use of a meridian stone, an artificial
point of reference exactly north of and at about four kilometers' distance from
the observatory. The scientists observed planets and their moons, the asteroids
that were only discovered at the beginning of the 19th century, and some
fainter stars in order to improve stellar charts. The Gerling Observatory is
the first place in Hesse, where positions of asteroids were read.
