he discovered a new star in m31 (the "andromeda nebula") on 20 august 1885. this object was designated as supernova "s andromedae". he observed the 1882 transit of venus in argentina. during the 1883 observation campaign of comet 6p/d'arrest he found five ngc objects working at the strasbourg observatory. in 1874 he became assistant at strassburg observatory, 1884 astronomer at dorpat observatory and 1887 director of bamberg observatory.