This artifact consists of a small cardboard box with a large paper label that originally contained “Astra II” spectrophotographic plates (48.1). The box contains three small brass-like metal components of unknown purpose.
48.2 One of these pieces is a flat piece of metal with a curved shape.
48.3 Another piece is a screw with a nut screwed onto it.
48.4 The third piece is a blocky irregularly-shaped piece of metal with an extended metal post. Wrapped around this post is a metal coil.
Accession Number: 2018.ast.48.1-4
Primary Materials: Cardboard, Paper, Copper Alloy
On the front of the cardboard box on a paper label:
FOR ASTRONOMICAL USE
ILFORD LIMITED, ILFORD, LONDON”
“MADE IN ENGLAND”
“STORE IN A COOL DRY PLACE AND OPEN ONLY IN A DARKROOM”
On the reverse of the cardboard box:
Dimensions (cm): Box: 9.2cm x 6.0 x 2.5
The box originally contained specialised astronomical spectrophotographic plates sold by Illford Limited. The metal pieces’ use and provenance is unknown.
“Astra II” plates were fast developing spectrophotographic plates with high sensitivity in the blue end of the spectrum.
Good. The box is in very good condition, although it no longer contains photographic plates. The paper label is peeling away from the cardboard a little along the bottom. The box is slightly scuffed along the corners and base.
The metal pieces, particularly 48.4, are slightly corroded with green-blue corrosion.
Box: Ilford Limited, Ilford, London; Contents: Unknown
Date of Manufacture: Box: 1925-1945
These objects were likely moved from the David Dunlap Observatory in Richmond Hill, Ontario in 2008, upon the sale of the observatory. It was stored at the Department of Astronomy and Astrophysics until 2017, when it was moved to a new storage location in McLennan Physical Laboratories.
It is unknown when the brass pieces were put inside the box or what they are associated with.
Regarding the plates:
Peter M. Millman, an astronomer at the Dunlap Observatory between 1933 and 1940, wrote about Astra II plates in a paper making recommendations for the photography of meteors: <a href=”http://adsbit.harvard.edu//full/1937JRASC..31..295M/0000304.000.html”>”Meteor Photography”</a> Journal of the Royal Astronomical Society of Canada Vol. 31 (1937) pg 304:
“In spectrophotography we have a large number of images corresponding to a single meteor, each image representing a different colour or wavelength; it is the maximum sensitivity of the plate in each of several colours that we are interested in, and no one type of plate is fastest in all regions of the spectrum… The Ilford Astra II plate is another very good ortho plate with high blue sensitivity.”
Information about Ilford, Limited: <a href=
“https://www.photomemorabilia.co.uk/Ilford/Chronology.html”>Ilford History and Chronology – Ilford Chronology”</a> [13/01/18]. This site contains a chronology of the Ilford Ltd. logo that used to date the box..