Part of a series which began with Fake news and the ethics of belief.
On 22 December 1870 there was a total solar eclipse.
A solar eclipse is when the moon passes between the earth and the sun, wholly or partially blocking out the sun as viewed from earth.
A total solar eclipse is a rare event, and even then its totality is only visible across a narrow band on the earth’s surface.
On 22 December 1870 the narrow band included parts of Portugal, Spain, Algeria, Sicily, Greece, Bulgaria and Ukraine.
The British Royal Astronomical Society organised an expedition to observe and record the eclipse.
William Clifford was invited along to take measurements in relation to the plane of polarisation of the light from the sun’s corona.1
At the time he was a Mathematics Fellow at Trinity College Cambridge.
The English Eclipse Expedition set off on the steamship Psyche, bound for Sicily.
The Psyche arrived in Naples on 14 December 1870, and steamed out of the harbour later that same day.
On the 15th she struck a rock off Catania, a town on the east coast of Sicily.
The Psyche was lost, but every life and every instrument was saved. The team could therefore carry on with the purpose of the expedition although based in Catania rather than Syracuse as originally intended.
Perhaps not surprising then that seven years later Clifford began The Ethics of Belief with this parable:
A shipowner was about to send to sea an emigrant-ship. He knew that she was old, and not over-well built at the first; that she had seen many seas and climes, and often had needed repairs. Doubts had been suggested to him that possibly she was not seaworthy. These doubts preyed upon his mind, and made him unhappy; he thought that perhaps he ought to have her thoroughly overhauled and refitted, even though this should put him to great expense. Before the ship sailed, however, he succeeded in overcoming these melancholy reflections. He said to himself that she had gone safely through so many voyages and weathered so many storms that it was idle to suppose she would not come safely home from this trip also. He would put his trust in Providence, which could hardly fail to protect all these unhappy families that were leaving their fatherland to seek for better times elsewhere. He would dismiss from his mind all ungenerous suspicions about the honesty of builders and contractors. In such ways he acquired a sincere and comfortable conviction that his vessel was thoroughly safe and seaworthy; he watched her departure with a light heart, and benevolent wishes for the success of the exiles in their strange new home that was to be; and he got his insurance money when she went down in mid-ocean and told no tales.2
1 ‘William Kingdon Clifford and the eclipse of 1870’, MacTutor History of Mathematics Archive, University of St Andrews (2015).
2 William Kingdon Clifford (1877, 1879), ‘The Ethics of Belief’. In Lectures and Essays, Volume II, L Stephen & F Pollock (Eds) London: MacMillan and Co, p177.
© Chris Lawrence 2021