|R. Fuess, Berlin
Fuess Model I reflecting goniometer and multipurpose optical instrument. Developed for high precision research to measure variations of crystal angles in a heating unit (missing).
Diameter of graduated circle 25 cm, graduation on solid silver. Four verniers with corresponding read out lenses. Both collimator and observation telescope fitted with Nicol prisms rotatable around its axis and small graduated circles similar to a Jamin/Sénarmont circle.
Signed R.Fuess, Berlin, circa 1870-1875. In 1879 the four read out lenses of the Model I goniometers were replaced by two micrometer microscopes.
A full instrument description may be found in Groth P. (1876), Physikalische Krystallographie Und Einleitung In Die Krystallographische Kenntniss Der Wigstigsten Substanzen, Leipzig, p. 464-466 and plate II (partially reproduced below also showing the heating unit)
Collection: private collection