Optical parts of Lassell's telescope
1840-1850
Optical parts of Lassell's telescope:- prism for 9-in reflector in green cardboard box; 3 multiple eyepieces; 5 small eyepieces; plane speculum on arm for 9-in; speculum for Newtonian finder in tin case 4 eyepices; 4 diaphragms (3 in two tin cases and one in wood case with metal lid)