Johann Jakob Thewalt
Kirchbergstraße 12, (now Töpferstraße) Höhr. Hesse-Nassau, Prussia. (now Höhr-Grenzhausen, Rhineland Palatinate).
Steinzeugfabrik / Stoneware manufacturer
Johann Jakob Thewalt was born on 10th June 1823 and died on the 13th March 1904. Jakob took over his father's tube factory, J. Thewalt, (founded 1802), in the 1840's. This company was independent of both A.J.Thewalt & J.P.Thewalt. He was probably the brother of Johann Peter Thewalt (b.1822 - d.1887), who in turn was the grandfather of Albert, who founded the company of Albert Jacob Thewalt. A gold medal was won in 1846. The factory closed down sometime after 1922.
Reference: Westerwald Adressbuch
Photo courtesy of Fox auctions 
Basemark on J.J. Thewalt stein 
An advertisement from Führer durch Höhr, dated 1907
Basemark on featured J.J. Thewalt stein (right) 