Arthur Eddington

Arthur Eddington, Plumian Professor of Astronomy and Experimental Philosophy at Cambridge, Director of the Cambridge Observatory

and member of the Board of Visitors and former Chief Assistant at the Royal Observatory, Greenwich. Photo c.1914 by Elliott & Fry. From Hutchinson's Splendour of the Heavens (1923). Also published on 28 March 1914 by The Illustrated London News.

Eddington and Cottingham arrived on Principe on 23 April and at Sundy, their observing site, on 28 April. In a letter dated 9 May, (Observatory Magazine, 1919, 42, 294) Cottingham describes the luxurious fast growing vegetation and oppressive humidity, before relating how a bottle of developer broke, ruining his new pyjamas. He rectified the problem by rinsing them in fixer before washing them. Eddington commented; ‘They were exposed, developed and fixed but after final washing there was no image’.

At Principe on 29 May, the day of the eclipse started with a very heavy thunderstorm which finished at 11:30. The sky began to clear just before totality at 14:13 and was briefly completely clear. Stars appeared on 7 of the plates and the remainder showed good images of the prominence. Only two plates were off sufficient quality and gave results consistent with Einstein’s prediction. 

Because of an impending strike by the steamship company, Eddington and Cottingham left Principe on 12 June and got back to Liverpool via Lisbon on 14 July.

They would have had to wait almost 6 months in Principe for the Hyades to appear in the night sky at the same position as they had during the eclipse, so the calibration plates of the eclipse field were taken with the astrographic, earlier in January and February that year, at Oxford, where the telescope was normally sited.

After the eclipse, Eddington was also able to enjoy some of the pleasures of Principe. He wrote to his mother (Eddington papers A4/9); ‘lunch on the beach off fish which we watched being caught’. ‘All the beaches are very pretty - a strip of golden sand between the cocoanut palms and the blue sea. I had a good bathe at Lapa – the only time in Principe & a black man went with me to see that I did not go too near the sharks.’ Other outings included, a Monkey Hunt at which no monkeys were seen and a trip to the ruined palace and church of a famous female slave dealer (Maria Correia) on the beach near Bom Bom.

Returning home on the SS Zaire, Eddington wrote to his mother; ‘ But the one good plate that I measured gave a result agreeing with Einstein and I think I have got a little confirmation from a second plate’ (Eddington papers).