flicker photometer
Date1915-1925
Inventory Number1996-1-0614
ClassificationPhotometer
Subject
Maker
John Frederick Simmance
Maker
Jacques Abady
1872 - 1964
Cultural Region
Place of Origin
Dimensionsphotometer: 19 × 12.5 × 17 cm (7 1/2 × 4 15/16 × 6 11/16 in.)
case: 22 × 20.5 × 17.5 cm (8 11/16 × 8 1/16 × 6 7/8 in.)
case: 22 × 20.5 × 17.5 cm (8 11/16 × 8 1/16 × 6 7/8 in.)
Material
DescriptionThis photometer is made of a wooden flicker disc box inside of which is a rotating white disc that produces the flicker. (On the side of the box there is a warning in English, French and German that says to not touch the disc.) The box is mounted on a stand, which can itself be mounted on an optical bench rail. There is a graduated quadrant (divided in single degrees) and a pointer that indicates the box's tilt. A knurled tightening screw holds the box in place. On the sides are sighting lenses. One side also has a turn key that rotates the white disc set inside the box. On top, a telescope is used to watch the flicker or, when the intensity of the two lights being observed is identical, the disc appears motionless.
Signedon quadrant: SIMMANCE-ABADY / PATENT
Curatorial RemarksThese two inventors were especially involved with gas lighting. See, for instance, their torch for lighting gas lamps 1901 patent, <a href="http://www.google.com/patents?id=LARpAAAAEBAJ&pg=PA1&dq=simmance+abady&source=gbs_selected_pages&cad=0_1#PPA2,M1" target="_blank">here</a>.
This exact type of photometer was sold by Baird and Tatlock (London) in the 1920s. See the 1924 trade catalogue in the CHSI library (Lib.3555).
FunctionA flicker photometer is used to compare and determine the difference of luminosity between two light sources. In this instrument, the two light sources are not seen together, as in the standard photometer, but one after the other alternately. The rate of variation is what cause the brightness flicker. When the latter has disappeared and only a uniform hue is seen, it means there is equality of luminance.
For more on this specific type of photometer, go to the following website.
For more on this specific type of photometer, go to the following website.
Arthur Howland
Date: circa 1920
Accessories: color discs
Object number: 1997-1-0986
Raytheon Manufacturing Company
Date: Copyright 1986
Accessories: one of two identical guides: 2004-1-0017a,b
Object number: 2004-1-0017a
Raytheon Manufacturing Company
Date: circa 1986
Accessories: one of two identical guides: 2004-1-0017a,b
Object number: 2004-1-0017b
Kollmorgen Corporation
Date: circa 1980
Accessories: Two instructions manuals: SPECTRA PRITCHARD PHOTOMETER, MODEL 1980A, CONDENSED OPERATING INSTRUCTIONS; INSTRUCTION AND MAINTENANCE MANUAL FOR SPECTRA PRITCHARD PHOTOMETER, Model 1980A. Both in gray archival box, C2-H1
Object number: 2004-1-0214a
Western Electric Company
Date: before 1933
Accessories: cords missing
Object number: RS0153
