Polarization projector c. late 19th century Duboscq & Pellin, Paris Brass, glass, cast iron, steel Used to study polarization phenomena by projection 19” high x 18” long This is a beautiful lacquered brass polariscope on a cast iron base. The height to the top of the instrument is 19” which can be extended to 26” by means of a slide-joint in the pillar. The length is approximately 18” depending on where the pieces are mounted on the slide rail. There is a Nicol prism in the small end eyepiece and then a series of three lens accessories that the distance between can be adjusted on the slide rail. The articulated and rotatable crystalline slice holder is attached to the back of the lens assembly at the front of the instrument. The projector appears to be complete and in working condition. The lacquered brass is in excellent condition with minor spotting, noting there is some loss of paint on the base. This type of optical bench was used to demonstrate and investigate polarization phenomena by means of projection, including the effect produced by a beam of polarized light that passes through a crystalline structure. An almost identical instrument is on the cover of the book, “The Physics Instruments of the Tuscan Technical Institute Optical”. See link: http://www.giunti.it/libri/scienza/gli-strumenti-di-fisica-dell-istituto-tecnico-toscano-ottica The brass rail is engraved “Mon Jules Duboscq, Ph. Pellin Paris”. Duboscq & Pellin were partners from 1883 to 1886. Late 19th Century. Antique Scientific Instrument