A rare mid 19th Century lacquered brass heliometer, (object glass micrometer) unsigned but stamped C.C.B. N°8 B. 1847 the 1¾in(4.5cm)diam., split lens adjusted by rack-and-pinion motion, with twin vernier scales divided 0-20/0-60, the telescope mounting -2¾in.(6.7cm)dia

細節

A rare mid 19th Century lacquered brass heliometer, (object glass micrometer) unsigned but stamped C.C.B. N°8 B. 1847 the 1¾in(4.5cm)diam., split lens adjusted by rack-and-pinion motion, with twin vernier scales divided 0-20/0-60, the telescope mounting -2¾in.(6.7cm)dia
see illustration

出版

Henry C.King The History of the Telescope pp150-154
G.L'E Turner and T.H.Levere Matinus van Marump.289

拍品專文

Cf.The heliometer or object glass micrometer was invented by the French mathematichen Pierre Bouguer(1698-1758 and developed by John Dollond (1706-1761) who presented a paper to the Royal Society on this instrument in 1754