Description:
This instrument is made of a Nicol prism mounted within a brass structure to which is attached a blackened brass diaphragm. On top is screw to which the handle is missing. It serves as a press to pressure on a piece of glass. The chamber sits atop a telescoping brass stand. An eyepiece was most likely attached to the structure (missing here).
The base has the letter "o" in white paint, meaning it was originally used at Radcliffe College. It also bears an old Harvard inventory number: "9 119".