Eby light-sensitive resistor cell and related items

Astronomy

Accession Number: 2019.ast.112 (DAA-0128)

Description:

This object is a small cardboard box containing a number of small electronic components, such as resistors and tubes. On the top, the box has a paper label on which someone has handwritten, “Eby cell and Purchases for same 1941”. The box can be held shut by folding down metal strips that hold the lid in place.

Inside the box, there are eight items:

1) A cylindrical black plastic piece with a reflective surface set deep into the cylinder. On the other side there are two electric contacts. This is the Eby cell.
2) A second roughly cylindrical piece, manufactured by the American Phenolic Corporation, has four contacts, and a metal rim.
3) A General Electric Radiotron vacuum tube.
4) Five resistors and variable resistors of different capacities and made by different companies, including Hart & Hedgeman and International Resistance Company Ltd.

Alternative Name:

Eby cell, light sensitive variable resistor

Primary Materials:

Cardboard, Glass, Plastic, Metal: Various

Markings:

On the original label of the box in which these items are contained: “To: David Dunlap Observatory,
RICHMOND HILL, Ontario.
FRAGILE
From BAUSCH & LOMB OPTICAL CO. LIMITED
388 YONGE STREET TORONTO ONTARIO”

Handwritten on this label: “Eby cell & Purchases for same 1941”

Embossed on the Eby cell: “H.H. EBY, INC.
PAT’D
2114591
A1”

Embossed on the 4-pinned object: “AMERICAN PHENOLIC CORPORATION CHICAGO MADE IN U.S.A. PAT 2087784”

Printed on the base and bulb of the vacuum tube: “GENERAL ELECTRIC
RADIOTRON
LICENSED BY THERMIONICS LTD.
PATENTED 1922-1969

MADE IN
CANADA

30”

Dimensions (cm):

Box: Length = 15.7, Width = 8.4, Height = 4.5

Function:

An eby cell is a variabe resister whose resistance varies in accordance with the quantity of light it received. It is useful in astronomy for recording changes in received light.

Condition:

Very Good: The box is in good condition, although the folding metal strips that hold the lid in place are rusting. The contents are also in very good condition, although all appear used. The paper labels of the resistors are discoloured.

Manufacturer:

Various: H. H. Eby, American Phenolics Company, General Electric, International Resistance Company Ltd, Hart & Hegeman

Date of Manufacture: 1930s-1941

Provenance:

These objects were apparently assembled in this box in or just after 1941, and likely stored since then at the Observatory. This box was moved from the David Dunlap Observatory in Richmond Hill in 2009, upon the sale of the observatory. They were stored at the Department of Astronomy and Astrophysics until 2017, when it was moved to a new storage location in McLennan Physical Laboratories.