Photronic Cell
Datecirca 1930
Inventory NumberWJ0203
ClassificationPhotoelectric Cell
Subject
Maker
Weston Electrical Instrument Corporation
founded 1888
Cultural Region
Place of Origin
Dimensions7.3 × 5.9 × 3.2 cm (2 7/8 × 2 5/16 × 1 1/4 in.)
Material
DescriptionMetal disc coated with selenium, encased in a bakelite cylinder with round glass-covered window. Surrounding the disc is a ring of copper with evenly spaced tabs pointing in toward the center of the glass. Two metal rods, the left one thicker than the right one, jut out from the bottom, and two round glass inserts, one aquamarine, the other indigo, flank the words "PHOTRONIC CELL" at the bottom of the plastic cylinder.
On the back of the cylinder is a slotted-head screw. Around that screw is a rough texture whose individual bumps are larger further from the screw.
Some scuffmarks on the sides of the cylinder.
On the back of the cylinder is a slotted-head screw. Around that screw is a rough texture whose individual bumps are larger further from the screw.
Some scuffmarks on the sides of the cylinder.
Signedmolded on plastic around window: WESTON NEWARK N J U S A
Inscribedmolded on plastic around window: McDel 594 PAT PEND / PHOTRONIC CELL
Curatorial RemarksIt is also possible that this cell was used to determine the difference between actual and perceived light intensity.
FunctionCalibration of light sources to ensure that light is of same intensity from one experiment to the next. The metal disc is coated on the front with a light-sensitive material, in this case selenium, which emits electrons when exposed to light. The electrons move into the copper ring, which is connected, via a galvanometer, to the anode on the backside of the disc. The galvanometer measures the potential created by the incident light and thereby indicates the intensity of the light.
ProvenanceDepartment of Psychology, Harvard University.
Walter Balcke
Date: circa 1958
Accessories: wooden case; blue pencil; pink eraser
in library folder (Lib 4927):
-twenty-one letters from Joseph L. Walsh, mathematics professor at Harvard University, to Walter Balcke, dated between 27 May 1957 and 24 January 1964 (letters thank Balcke for the many mathematical models he gifted to the Mathematics Department, praise his skill and ingenuity, many invite him to faculty and personal luncheons, and one letter provides an analytic solution to the "13-point problem" behind one of Balcke's models)
-three letters from Garret Birkhoff (then Chairman of the Harvard Mathematics Department) dated 3 March 1954, 4 January 1955, and 10 January 1955, each expressing gratitude (and in one case, an official department thank you) for the many mathematical models he gifted to the mathematics department
-photocopy of original envelope in which correspondence between mathematics department and Walter Balcke was stored (original was destroyed on 13 July 1997)
-photocopy of instructional card for object 1997-1-1671
- seven instructional cards that accompany the following Balcke models: Pascal's Theorem, Brianchon's Concurrent Lines, Trisector, Twelve Point Ellipse, Rolling Parabola, unknown, Equation Solution with a 'Constant' Variable and Thread
- photograph of the display case containing Balcke's models in the Harvard Mathematics department
Object number: 1997-1-1671
American
Date: 1910-1930
Object number: 2007-1-0513
English
Date: circa 1820
Accessories: wooden case
brass frame with points
glass arm
handle
broken glass (in package)
Object number: DW0504
Weston Electrical Instrument Corporation
Date: circa 1930
Object number: 2007-1-0039a
Weston Electrical Instrument Corporation
Date: circa 1930
Object number: 2007-1-0039b
Carl Zeiss Jena
Date: circa 1926
Accessories: wooden box with two hook-and-eye latches to fasten front opening; in instrument file: instruction book (photocopy); Geissler tube labeled "H2"; carboard tube containing German thermometer C in stainless steel holder that screws into instrument; glass bottle with cork stopper labeled "Monobromnaphthalin, Germany nD=1 658"; small round cardboard box labeled "For Pulfrich Refractometer" containing one tubulure
Object number: 1996-1-0229
Mepro Electric, Inc.
Date: 1986-1990
Accessories: AC/DC adapter; carrying pouch; brochure
Object number: 1995-1-0015
