A refracting telescope with a split objective lens, used for finding the angular distance between two stars.
- ‘After the expedition the heliometer was donated to the Observatory who built a tower for it.’
- ‘The heliometer is shown on display at the Science Museum in London.’
- ‘A heliometer is a refractor, with the objective cut in two, which was used to measure small angular distances.’
- ‘And so, the phenomenon in 1882 was observed by cameras held by the French and the Americans, and timings were measured with the help of heliometers in most European organizations.’
- ‘He also determined the distances, using the heliometer, of twenty of the brighter and nearer Southern stars.’
Mid 18th century: from helio- ‘of the sun’+ -meter (because it was originally used for measuring the diameter of the sun).
We take a look at several popular, though confusing, punctuation marks.