The Boyden 60-inch mirror being placed into a vacuum chamber

Typed caption in Afrikaans: "Die spieël word in die groot vakuumkamer (vertikaal) geplaas. Nadat die vakuumkamer se 'deksel' opgeplaas is, word 'n pomptyd van ongeveer 32 ure benodig om die vereisde vakuum te bereik. Aluminimum [sic] word op verskeie plekke in die vakuumkamer verhit totdat Al-atome begin verdamp en dan op die spieël neerslaan.". Translation: "The mirror is placed vertically in the large vacuum chamber. After the lid of the chamber is in place, some 32 hours of pumping time are required to achieve the necessary vacuum. Aluminium is heated in several places within the chamber until aluminium atoms start to evaporate and are deposited on to the mirror.". PB14_0001 and PB14_0002 were part of a poster display titled: "Telescope Mirror of Boyden Observatory" with explanation (in Afrikaans): "The mirror of the 1.52-m telescope at Boyden Observatory near Maselspoort was realuminised at the South African National Observatory at Sutherland in the Small Karoo during February. The 1.52-m telescope is the second largest telescope in the country." At least one photograph and about one-quarter of the poster has been lost. n/a. Extent: 1 photograph, mounted on card. Size and dimensions of original material: Height 9cm, width 13cm. Condition of original material: Negligible damage. Author(s)/Creator(s): English|English|Afrikaans. Scribe(s): Latin. Publisher(s): Left-to-Right. Editor(s): Unrestricted. Volume number: N/a. Original institution reference: PB14_P0576.