The observatory at the Stintfang
The first direct ancestor of the modern Hamburg Observatory was established by entrepreneur Johann Georg Repsold. 1798, Repsold had founded a manufactory for precision mechanics that, over the course of several decades, evolved into the globally renowned company A. Repsold & Söhne that lasted until 1919. Through his work on geodesic instruments, Repsold had found an interest in astronomy. In 1802, he was granted permission to establish a private observatory atop of bastion Albertus, a part of the Hamburg's fortifications, which was located at the Stintfang. The hexagonal building was completed a year later and featured a canopy that already somewhat resembled a modern telescope dome with its meridian slit. It housed Repsold's smaller passage instrument, a 3.5 foot meridian circle and a precision pendulum clock. Within a few years, Repsold accumulated an assortment of telescopes and instruments that put even some prestigious, contemporary public observatories to shame.
Repsold's observatory remained untouched when, in 1804, Hamburg's main wall was razed as proof of neutrality in the Coalition Wars. It outlasted Gabory's observatory but not by much. By April 1811, the building and instruments had taken severe damage from cannon fire. The next year, the French administration forbade any civilian use of the rebuilt battlements. The instruments were stored away and the building was torn down, ending up as firewood. Repsold appealed to the senate to found a municipal observatory. In order to boost his chances, he had found a mutually beneficial agreement with the Hamburger Admiralität, roughly equivalent to the harbour administration, that intended the expansion of its nautical school. Given the war and and mounting destruction, the joint proposal was turned down, though.
For years, customers of Repsold's quality instruments were few and far in between and he was forces to make a living off low quality nautical tools imported from Britain. With no place to set it up, his unused and disassembled meridian circle was eventually sold to Carl Friedrich Gauß, director of the observatory in Göttingen.