Julius Christian Johannes Zeller (24 June 1822, Mühlhausen am Neckar – 31 May 1899, Cannstatt) was a German mathematician.
[1] Originally trained in mathematics, geography and theology, in 1874 Zeller became Director of the Seminary in Markgröningen and a girls' orphanage.
He was later awarded the Order of Friedrich, First Class, and the Ritterkreuz of Württemberg.
Each of these four similar papers deals firstly with the day of the week and secondly with the date of Easter Sunday, for the Julian and Gregorian Calendars.
He also produced a reference card, Das Ganze der Kalender-Rechnung.