Repsold (Johann Georg) Korrespondenz
Johann Georg Repsold (* 19. September 1770 Wremen † 14. January 1830 Hamburg) was a German fine mechanic and founder of a workshop for astronomical instruments. Since 1808 he worked together closely with Heinrich Schumacher to build more exact trigonometric instruments and telescopes. He corresponded with Gauß mainly on achromatic doublets and a new median circle he built for the Göttingen observatory.
Sources: Wikipedia, Wikisource