Sir John Herschel: „Decaying framework of William Herschel’s forty-foot telescope at Slough,
Sir John Herschel: „Decaying framework of William Herschel’s forty-foot telescope at Slough, 1839, experimental negatives: left, silver on paper, summer 1839; right, silver on glass, 9. September 1839“, jeweils ca. 10 cm Durchmesser (aus: Ann Thomas, Beauty of Another Order. Photography in Science, Ausstellungskatalog National Gallery of Canada, Ottawa/Ontario, New Haven, London: Yale University Press, 1997, S. 46) Fenster schliessen