
4 0 c m
33cm
actual image size: 25cm x 32cm
Description
Photograph of an equatorially mounted heliometer, of 7 inch aperture, at the Cape Observatory, in South Africa. Made by Repsold and Sons, Hamburg in Germany, the instrument has a split main lens that is used to measure very precisely the angular separation of objects in the heavens. Sir David Gill (1843-1914), Scottish astronomer, used this heliometer to determine stellar and solar parallax to measure the distance to nearby stars and that of the Sun.
Image Details
Image Ref.
10418871
© Science Museum / Science & Society Picture Library