Refractometers and related instruments click images for more information Abbe total refractometer Abbe refractometer (black lacquered and nickel plated brass) on blackened cast iron base. Rotatable glass hemisphere with graduated circle and mirror. Movable telescope connected to a graduated circle with vernier read-out. Height 33 cm, base diameter 15 cm. Signed on the graduated circle "R. | FUESS | BERLIN-STEGLITZ" and serial number "5929", ca. 1954. With a 7 page instruction booklet, dated 1954 (15 x 21.1 cm). Pulfrich type refractometer Nickel plated brass and black painted cast iron Pulfrich type refractometer (height 30 cm, circle diameter 12 cm). Unsigned, but made by Max Wolz, Bonn, first half 20th century. Circle of Jamin and Sénarmont Lacquered brass circle of Jamin and Sénarmont for the determination of angles and refractive indexes and for the study of the polarization of reflected light on metallic and crystalline substances and on liquids. The circle (diameter 26 cm) may be oriented either horizontally or vertically. The small circles (diameter 11 cm) with alidades and vernier read-out accommodate the analyzer and polarizer. The instrument (total height 45 cm) was designed to accommodate a number of accessories described in the catalogue of Ph. Pellin (Fascicule IV) and in a paper of Jamin (Annales de Chimie et de Physique, 3e série, tome XXIX, juillet 1850) This instrument misses most of the original optical parts and the accessories. Signed "J. Duboscq à Paris", 2nd half 19th century Babinet goniometer / refractometer Brass circle (21 cm) with fixed collimator and rotatable telescope and central platform with vernier read-outs. Total height : 39 cm. This type of instrument, often called "Babinet’s goniometer", was originally designed for the measurement of interplanar angles and refractive indexes; it was used also for spectroscopic investigations. Signed "Ph & F Pellin Paris", early 20th century (1912 or later). Gemologists compendium Set of different instruments in glass fronted wooden cabinet (lacquered black, 30.2 x 22.6 x 13.2 cm). The items include: microscope (lacquered and black lacquered brass, height 27 cm) signed on the base "J.H. STEWARD. LONDON." with two specimen holders; bull's eye condenser lens (lacquered brass); tweezers; refractometer (lacquered and black lacquered brass, 7.8 x 4.2 cm), signed "J.H. STEWARD | LONDON" and numbered "267"; dichroscope (lacquered and black lacquered brass, tube length 6.4 cm, diameter 1.1 cm), signed "J.H. STEWARD | LONDON"; separate compartment with mahogany box with glass bottles containing heavy liquids (methylene iodide etc.); stone tester (three hardness points and gauge) nickel plated brass, with instruction leaflet (12.8 x 7.3 cm). First half 20th century.