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Optical parts of Lassell's telescope

1840-1850

Speculum Mirror, 1861

1861

Oval shaped secondary speculum mirror with cover, from the 6-foot Rosse telescope

Oval shaped secondary speculum mirror with cover

1845-1850

Two plane speculums and two polishers by Lassell, with Lassell's M.S. directions

Two plane speculums and two polishers by Lassell

1840-1850

Two plane speculums by Lassell, with Lassell's M.S. directions

Two plane speculums by Lassell

1840-1850

Elliptical plane mirror (diagonal flat for Newtonian telescope) minor axis 1 1/2", major axis 2" in (full) soldered in usual way to circular brass disc, cylindrical cover of brass 1 3/4" deep, cover of brass 1 3/4" deep, cover and brass disc inscribed 1 "A4"

Elliptical plane mirror (diagonal flat for Newtonian telescope) minor axis 1 1/2"

1780-1820

Optical parts of Lassell's telescope:- prism for 9-in reflector in green cardboard box; 3 multiple eyepieces; 5 small eyepieces; speculum for Newtonian finder in tin case 4 eyepices; 4 diaphragms (3 in two tin cases and one in wood case with metal lid)

Optical parts of Lassell's telescope

1840-1850