foot candle meter
Date1935 - 1945
Inventory Number2003-1-0117
ClassificationOptics Apparatus
Subject
Maker
Weston Electrical Instrument Corporation
founded 1888
Cultural Region
Place of Origin
Dimensionscase: 21 × 19 × 11.5 cm (8 1/4 × 7 1/2 × 4 1/2 in.)
Material
Accessorieslead wires; photoelectric probe; case
DescriptionA Weston Illumination Meter, model 756, with a leather case with handle. The measurements are made in foot candles, a non-SI unit of measurement for illumination, defined as the amount of light that the inside surface of a sphere with a radius of 1 foot would receive if there were a point source of one candela in the center of the sphere. In other terms, it is equal to one lumen per square foot.
From the included information card on this instrument: "The instrument indicates the illumination in Foot Candles, based on the New Candle, on the surface of the light target, or lumens per square foot evenly distributed. It is provided with a filter which changes the color sensitivity of the photoelectric cells to match that of the human eye, and can therefore be used to measure tungsten light, flourescent lights of various colors, etc., without correction."
The "New Candle" refered to here is what would later come to be the SI united of the candela. In 1946, what constituted a "candle" was standardized by the Commission Internationale de l'Éclairage (International Commission on Illumination). It was based on the illumination of a black body set at the freezing point of platinum
To use the instrument, the subject range is set by means of a selection switch, and the target is placed on or near the surface to be measured, with the photosensitive side parallel to the light rays. To measure maximum illumination, the photosensitive side should be placed perpendicular to the light rays.
From the included information card on this instrument: "The instrument indicates the illumination in Foot Candles, based on the New Candle, on the surface of the light target, or lumens per square foot evenly distributed. It is provided with a filter which changes the color sensitivity of the photoelectric cells to match that of the human eye, and can therefore be used to measure tungsten light, flourescent lights of various colors, etc., without correction."
The "New Candle" refered to here is what would later come to be the SI united of the candela. In 1946, what constituted a "candle" was standardized by the Commission Internationale de l'Éclairage (International Commission on Illumination). It was based on the illumination of a black body set at the freezing point of platinum
To use the instrument, the subject range is set by means of a selection switch, and the target is placed on or near the surface to be measured, with the photosensitive side parallel to the light rays. To measure maximum illumination, the photosensitive side should be placed perpendicular to the light rays.
Signedon plaque: WESTON ELECTRICAL INST. CO. / NEWARK, N.J., U.S.A. / ORDER NO. 21730-PH [rest of number is cut off in photo]/ U.S.
Inscribedon upper plaque: WESTON ELECTRICAL INST. CO. / NEWARK, N.J., U.S.A. / ZERO CORRECTOR
on lower plaque: METER, FOOT CANDLE / PHOTO ELECTRIC ME-86/V / SERIAL NO. / WESTON ELECTRICAL INST. CO. / NEWARK, N.J., U.S.A. / ORDER NO. 21730-PH [rest of number is cut off in photo]/ U.S.
on scale: FOOT CANDLES / USE ONLY WITH TARGET BEARING SAME NUMBER AS METER
Weston Electrical Instrument Corporation
Date: 1935-1945
Accessories: original case; photoelectric probe; lead wires
Object number: 2004-1-0394
Eastman Kodak Company
Date: circa 1910
Accessories: orignall paper box with instructions printed on it
Object number: 1995-1-0032
Théodore and Albert Duboscq
Date: 1880-1890
Accessories: small metal piece
Object number: 1998-1-1635
W & A. K. Johnston, Ltd.
Date: c. 1872
Accessories: rectangular and round wood stretchers
Object number: 2008-1-0308a
Date: 1960-1970
Accessories: instruction manual; business reply card; guarantee; cord; key to lock
Object number: 1997-1-0108
Joseph Wright of Derby
Date: 1768
Accessories: in frame
Object number: 2003-1-0052
See also/See also
