COMPARATIVE LITERATURE: A wall regulator of related design by Johann Friedrich Gutkaes (No.1194) and dating from c.1850 is illustrated in Antiquarian Horology, No.6, Vol.21, Winter 1994, pp.538-539, figs.2a & 2b. That example also has a four-jar mercury pendulum and an inverted escapement; a 'force constante a deux boules' gravity escapement. No.1191, illustrated in Derek Roberts Precision Pendulum Clocks, France, Germany, America, and Recent Developments, Schiffer, 2004, p.181, Figs.35-5A,B,C,D also has the 'deux boules' escapement.
Christian Friedrich Gutkaes (1784-1845) was appointed clockmaker to the Dresden Court in 1842. Adolf Ferdinand Lange was his pupil in Dresden before moving to Paris to work with Winnerl, a pupil of Breguet's. In 1842 he married Lange's daughter. See Jürgen Abeleer, Meister der Uhrmacherkunst, Dusseldorf, 1977.
The Gutkaes and Lange partnership commenced in 1844 and in the Exhibition of that year and the following year they showed two regulators with gravity escapements. Lange ran Gutkaes' shop in conjunction with his brother-in-law Bernard Gutkaes. See Derek Roberts, op.cit., p.117.