Reflection Goniometer / Polarizing Spectrometer model 0450

Physical Description

The Reflection Goniometer sits on a fix iron tripod with brass adjustable feet. Everything from the tripod up, would be made of brass.

A disc (A) sits atop the center of the tripod is a circular scale with graduations from 0 to 360 degree, it rotates and is divided into third of degrees. Two verniers reading to 20 seconds orbit the scale horizontally. A horizontal disc (B) is raised from the center of the circular scale with textured edge for ease of handling/ rotating. A rotation locking screw protrudes out inbetween he circular scale and disc B.

A pair of smaller disc(C) sits atop of dics B, it consists of two circular plate sandwiching a concave piece of spring kept in position by one fastening nut and one pairs of leveling nuts attaching to three screws afixed to the top plate . The leveling nuts are used to adjust horizontal level of disc C. A locking screw protrudes out inbetween disc B an disc C that can lock the rotation between the discs.

The Top plate (stage) of Disc C also has a hole for positioning a missing a heavy prism as well as a secondary off-center hole for a missing prism-holding arm. Both disc C and disc A can be locked to disc B through locking screws and rotate with disc B.

Under dics A are two arms extended out supporting a collimator and a telescope. The fixed arm extend out horizontally and is attached to a small cylindar supporting the collimator. Two adjustment screws are attached at the foot of the support that can lock the rotation of disc B as well as slightly adjust its horizontal angle. The rotating arm is attached to a replacement stainless steel cylindrical support and is missing the telescope pointing to the center of the rotating discs. Two adjustment screws are also attached at the foot of the support that locks the rotation of the arm as well as provides precise angle adjustment. The Collimator has on the outer end a square with a spring loaded adjustable gate allowing desired amount of light to go in. The spring for the mechanism is no longer functional, a screw knob for adjusting the light gate is also missing. The other end for of the Collimator has a convex lens that would make incoming light parallel toward the missing prism

Functional Description

To use the reflection goniometer, the user would a fix the small crystal to the center of the top disc that is held by the missing holding arm. Open and adjust the width of the slit on the far end of the collimator with the missing thumb screw, adjust the distance of the opening to the lens till the light hitting the prism is parallel. Rotate the arm holding the telescope to 180 degree to the collimator. Look through the telescope and set the stage level with the two leveling nuts. Use the adjustment screws under arms of telescope and collimator to center the crystal in the scope. After

• “Spectrometer.” Smithsonian Institution National Museum of American History. Accessed March 30, 2024. https://americanhistory.si.edu/collections/nmah_1463298.
• “Reflecting Goniometer.” Virtual Museum of the History of Mineralogy. Smithsonian Institution. Accessed March 30, 2024. https://www.mineralogy.eu/gonio/horizontal/SIP.html.
• “Goniometer.” Smithsonian Institution. Accessed March 30, 2024. https://www.si.edu/es/object/nmah_1184284.
• “Antique Swiss Scientific Instrument Societe Genevoise d’instruments de Physique.” Worthpoint. Accessed March 30, 2024. https://www.worthpoint.com/worthopedia/antique-swiss-scientific-instrument-1883706169.
• Société Genevoise pour la Construction d’Instruments de Physique et de Méeanique. “Illustrated Price List of Physical and Mechanical Instruments... 1900.” HathiTrust. Accessed March 30, 2024. https://babel.hathitrust.org/cgi/pt?id=mdp.39015010967688&seq=50.