The role of three William Herschel telescopes in colonial India

Abstract

In this paper we provide information on some of the telescopes to which one of the most prominent names in the history of astronomy is attached: Frederick William Herschel. He built telescopes of different apertures and focal lengths, the majority being 7-ft or 10-ft focus, and gifted or sold to those interested. We find that at least three 10-ft Herschel telescopes were brought to Calcutta, India, and were used for astronomical observations by British residents and the Christian missionaries in the city. One of these belonged to David Hare, a Scottish watchmaker and philanthrope and the other to James Calder, a prominent merchant of Calcutta. The third one had been gifted by Sir John Herschel to his brother-in-law, Dr. Duncan Stewart, Surgeon in the service of East India Company, in 1834 while Herschel was living at the Cape of Good Hope. In 1844, Dr Stewart presented the telescope to the General Assembly's Institution established by the Bengal Mission of the Free Church of Scotland. We also include in this paper the hitherto unpublished "Herschel Manuscript Catalogue of Stars" visible on the horizon of Calcutta that Sir John had drawn up to accompany the 10-ft telescope, reproduced with the kind permission of the Syndics of Cambridge University Library. The three Indian-based Herschel telescopes are no longer extant. Since 1924 there has been a search for all surviving Herschel telescopes, whether complete, incomplete or missing, but those that were brought to India have yet to be included in these studies-which we hope will now be rectified through this paper.