Accession No
6675
Brief Description
Joly photometer, c. 1900
Origin
Maker
Class
optical
Earliest Date
1880
Latest Date
1950
Inscription Date
Material
wax; wood; metal (brass, aluminum)
Dimensions
30mm (width) x 40mm (height) x 45mm depth)
Special Collection
Michael J. Clark Bequest
Provenance
Inscription
Description Notes
Joly photometer, c. 1900.
A small device for measuring light intensity using two paraffin wax blocks separated by a layer of aluminum foil. The blocks are housed in a wooden case, with openings at either end for light to enter and a third opening at the front with a brass eyepiece for observation. The object has a modern typed label, "WAX-BLOCK PHOTOMETER."
Condition: good
References
Events
Description
Wax absorbs and refracts light such that it glows according to the intensity of the light; using two light sources directed at the two wax blocks, one can adjust the photometer's distance from each source in order to measure the relationship between light intensity and distance, thus demonstrating the inverse square law.
25/09/2018
Created by: Matthew Green on 25/09/2018
FM:47372
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