Description:
This instrument consists of a mahogany tube that can pivot horizontally and vertically. At each end is found a circular black mirror mounted on two supporting rods. One of these is actually a semi-circular brass scale marked in single degrees, numbered by tens, and reading from 90°-0-90°. When the mirror pivots, a pointer on the semi-circular scale indicates the angle of rotation. At one end there is also a full circular scale in brass, marked in single degrees, numbered by tens and reading from 90°-0-90°-0-90°. This scale indicates the horizontal angle of rotation of the black mirror to which it is fixed. The polarimeter is supported by a turned round base and pillar, the former weighted to give the apparatus more stability.
This device has black mirrors as both the polarizer and analyzer, as is consistent with the earliest polarimeters designed in the 1810's (quartz and Nicol prisms became more widely used after 1830).
It is marked with an old Harvard number: 9 174.