Robert-Aglaé Cauchoix
Robert-Aglaé Cauchoix (24 April 1776 – 5 February 1845) was a French optician and instrument maker, whose lenses played a part in the race of the great refractor telescopes in the first half of the 19th century.
Instruments
[edit]At first Cauchoix produced a wide range of scientific instruments including barometers and micrometers, but he soon specialized in optics, making spherometers and objectives.[1][2] He made a telescope for the Paris Observatory in 1820 and in 1825 he made a 6.5 inch (16.5 cm) refractor for the observatory of the Collegio Romano, a Jesuit academy in Rome. In the Royal Observatory, Greenwich an 1838 instrument named the Sheepshanks telescope includes an objective by Cauchoix.[3] The Sheepshanks had a 6.7 inch (17 cm) wide lens, and was the biggest telescope at Greenwich for about twenty years.[4]
An 1840 report from the Observatory noted of the then-new Sheepshanks telescope with the Cauchoix doublet:[5]
The power and general goodness of this telescope make it a most welcome addition to the instruments of the observatory
Great refractors
[edit]Although the reflector telescope was invented in the second half of the 18th century, technological difficulties made the refractor the telescope of choice until the mid-1850s.[citation needed] Improvements in lens production, like the introduction of the achromatic lens by John Dollond, spawned an aperture size race that started in the early 1820s with a telescope made by the German optician Joseph von Fraunhofer. Cauchoix must be credited holding the lens size record three times this period. In 1831, Cauchoix made a 13.3 inch (almost 33.8 cm) refractor for the Irishman Edward Joshua Cooper, who used it to observe Halley's Comet in 1835 and a solar eclipse in 1836.[6][2]
In 1829, Cauchoix made an 11.75 inch lens for a French customer, but sold it to the British astronomer James South.[6] South used it for his new telescope, which he found defective due to problems with the equatorial mount.[2] In 1838, this telescope was dismantled, but the lens by Cauchoix served in other instruments until 1989.
See also
[edit]References
[edit]- ^ "Robert-Aglae Cauchoix". M. S. Rau Antiques. Archived from the original on 22 February 2014. Retrieved 27 February 2014.
- ^ a b c Launay, Françoise (2018). "Robert Aglaé Cauchoix (1776–1845) and his Large Achromatic Object-glasses". The Antiquarian Astronomer. 12. Society for the History of Astronomy: 2–16. Bibcode:2018AntAs..12....2L.
- ^ "Sheepshanks telescope". UK: Royal Museums Greenwich. Retrieved 27 February 2014.
- ^ Tombaugh, Clyde W.; Moore, Patrick (2017-09-15). Out of the Darkness: The Planet Pluto. Stackpole Books. ISBN 9780811766647.
- ^ Astronomical Observations, Made at the Royal Observatory at Greenwich, ... Clarendon Press. 1840.
- ^ a b Abrahams, Peter. "Cauchoix biography". Antique Telescope Society. Retrieved 27 February 2014.
External links
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