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'Pathological set' of twelve objective lenses

circa 1920-1939
Objective lens of 5.9-inches aperture made by Charles Tulley of Islington for a refracting telescope on an English type equatorial mounting made by Dollond. Both elements of the achromatic lens are notched for alignment in the brass cell while the flint rear lens has numerous small air bubbles. The 5.9-inch objective lens for the Smyth Telescope was made by Charles Tulley (the elder) of Islington, London. It is probably his finest work and was judge first class when it was tested in 1929 by Dr W.H.Steavenson. The large flint blank for the Tulley lens was obtained by Sir James South from the Optician Cauchoix in Paris.

Objective lens of 5.9-inches aperture, for a refracting telescope on an English type equatorial mounting

1822-1824
'Pathological set' of twelve objective lenses and brass control knob, each lens with a known defect, in fitted box, with separate telescope, all by Cooke, Troughton & Simms Ltd, for demonstrating the effects of imperfect lenses, probably c. 1920-1939. Also three home-made 'artificial stars' consisting of ball bearings mounted on rods on a wooden base. (One lens cracked.)

objective lenses and control knob

circa 1920-1939