“Solar Spot Mania”: The Origins and Early Years of Solar Research at Kew Observatory,1852–1860

The building of the photographic solar telescope or “photoheliograph” at Kew Observatory near London in the 1850s and the successful programme of solar photography carried out with it have generally been taken as a direct response to Sir John Herschel’s well-publicised 1854 call for collaborative studies of sunspots. This paper uses archival evidence to show that the story of the photoheliograph’s origins and how it came to Kew in the first place is much more complex than has hitherto been acknowledged and that it was really the work of several individuals. I also argue that the photoheliograph and the work carried out with it were largely directed and financed by the wealthy Warren De La Rue and that so as far as the photoheliograph was concerned, Kew was not a public observatory, as has been asserted.