mirror on stand
Date1937-1941
Inventory Number1996-1-0677
ClassificationMirror
Subject
Maker
Wilmer C. Anderson
User
Department of Physics, Harvard University
founded 1884
Cultural Region
Place of Origin
Dimensions44 × 40.6 × 38 cm (17 5/16 × 16 × 14 15/16 in.)
Material
Accessoriescover is stored separately
DescriptionSilvered mirror on a heavy tripod stand. Each leg has a leveling screw. The position of the mirror can be adjusted and rotated in all three axes by using micrometric screws. An inscription taped on one leg mentions: "Danger / do not touch surface / of MIRROR / silvered on frame."
Signedunsigned
Curatorial RemarksThis mirror, though it could have been used in earlier experiments, is very similar to one found in the next experimental set-up Anderson devised to measure the speed of light. This new set-up, described in the 1941 article of the <i>Journal of the Optical Society of America</i> involved new types of Kerr cells, a new light source (a 1000-watt water-cooled mercury arc lamp) and changes in mirror supports.
FunctionThis mirror was part of a larger experimental set-up devised by Wilmer C.
Anderson to measure the speed of light. According to the description in the Review of Scientific Instruments, the set-up consisted of a light source (a 500-Watt Point-O-Lite bulb), Nicol prisms, a Kerr cell (a photoelectric cell that replaced the human eye; it is really the innovation here), and mirrors.
In the same article, Anderson said that after a series of 651 measurements, the mean result for the speed of light was 299,765 km/s ± 15 km/s. Two years later, he was able to get an even more precise number using 2895 observations: 299,776 km/s ± 14 km/s.
The origins of Anderson's work is found in his Ph.D. dissertation at Harvard University, completed in 1936 and entitled A High-Frequency Method for Measuring the Velocity of Light.
Anderson to measure the speed of light. According to the description in the Review of Scientific Instruments, the set-up consisted of a light source (a 500-Watt Point-O-Lite bulb), Nicol prisms, a Kerr cell (a photoelectric cell that replaced the human eye; it is really the innovation here), and mirrors.
In the same article, Anderson said that after a series of 651 measurements, the mean result for the speed of light was 299,765 km/s ± 15 km/s. Two years later, he was able to get an even more precise number using 2895 observations: 299,776 km/s ± 14 km/s.
The origins of Anderson's work is found in his Ph.D. dissertation at Harvard University, completed in 1936 and entitled A High-Frequency Method for Measuring the Velocity of Light.
ProvenanceFrom the Department of Physics, Harvard University.
Nachet et Fils (I)
Date: 1862-1872
Accessories: 3 Objectives; 2 oculars; substage mirror with mounting screw lost; 1 prepared slide
Object number: 1030
See also/See also
