Painted black rectangular box with open sides. The top of the box is pyramid-shaped, and detachable. The top of the pyramid narrows to a cylindrical tube that ends in an eye piece. A metal rod, so the instrument can be attached to a stand, protrudes perpendicularly from one of the closed sides of the box.
Visible in the open sides of of the box are mirrors arranged at angles to direct light into the closed portion.
Accession Number: 2009.ph.149
Alternative Name: Grease Spot Photometer
Primary Materials: Metal: Iron Alloy, Glass
Dimensions (cm): Height = 13, Width = 21.5, Length = 27
This instrument is used to visually compare the luminosity of two light sources. By looking through the eyepiece the user can see, by means of the mirrors, the paper containing a grease spot from opposite sides. Placing a light source on one side of the instrument illuminates the paper and its grease spot. By placing the photometer between two light sources and comparing the relative brightness of the grease spots, the viewer can judge the relative luminosity of the two sources.
Good: The exterior of the instrument is painted; the paint is mostly intact, with a small number of marks and scratches. This Instrument is missing its grease-spot paper, and so is non-functional.
Date of Manufacture: 20th Century
Acquired from Physics Department, University of Toronto.
<a href=”http://de.wikipedia.org/wiki/Fettfleck-Photometer”> Fettfleck-Photometer (Wikipedia entry, German only)</a>