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Papers of Sir Arthur Eddington
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Summary of Chapters XII (second part), XIII, and XIV, with an editorial note

Chapter XII [continued].
§ 125. Symbolic occupation.
§ 126. Einstein-Bose particles.
§ 127. Photons.
§ 128. Life-time of the mesotron.

Chapter XIII: Epistemological Theory.
[§§ 129–136.] As in Proceedings of the Cambridge Philosophical Society, vol. xl (1944), p. 37, expanded.

Chapter XIV. Summary.
§ 137. The principles of fundamental theory.

Papers of Sir Arthur Eddington

  • EDDN
  • Fonds
  • 1897–1982

Eddington, Sir Arthur Stanley (1882–1944), theoretical physicist and astrophysicist

Letters from A. S. Eddington to Sarah Ann Eddington: Brazil Eclipse Expedition

In 1912 Eddington led an expedition from the Royal Observatory to Brazil to observe and photograph a total eclipse of the sun. These letters contain an account of the expedition. Eddington specifically asked his mother to preserve the letters because he was keeping no other record of events (see A2/5), and she seems to have been careful in carrying out his request, as the sequence is probably complete. The letters are numbered from 1 to 9 in a contemporary hand, and the ninth letter, finished when the writer was about three days’ sail from home, was almost certainly the last. These letters formed the basis of the account in Eddington’s Notebook (ff. 96–102), and they were consulted by Douglas, who quoted from A2/8 (pp. 18–19).

Eddington and his assistants C. R. Davidson and J. J. Atkinson left Southampton aboard the steamship Arlanza on 30 August and arrived at Rio de Janeiro on 16 September, where they were joined by T. N. Lee, an Englishman deputed by the Brazilian Government to assist them, and J. H. Worthington, an amateur astronomer. Six days later the party arrived at Passa Quatro, their chosen observation point—preferred to other possible sites at Cruxeiro, Christina, and Alfenas—and on 3 October they were joined by two volunteers, Leslie Andrews and O. Couto de Aguirre. A local man, Pierre Seux, also volunteered to help by counting seconds during totality. The eclipse took place on the 10th, but unfortunately observations of the phenomenon were prevented by rain and the expedition was largely unsuccessful. Eddington and his companions left Passa Quatro on 20 October and sailed for home on the Danube on the 23rd. The date of their arrival in England is not recorded, but towards the end of the voyage they were expecting to be at Southampton on 10 November. A report of the expedition, by Eddington and Davidson, was printed in MNRAS (lxxiii, 386–90) the following year. Notes also appeared in The Observatory, xxxv (1912), 328–30, 410, and xxxvi (1913), 62–5.

Letters from A. S. Eddington to Sarah Ann Eddington and Winifred Eddington: Madeira and the Eclipse at Principe

In 1919 two expeditions were dispatched from Britain to observe a total eclipse of the sun, the object being to test Einstein’s general law of relativity by determining what effect, if any, is produced when the path of a ray of light crosses a gravitational field. One party, comprising A. C. D. Crommelin and C. Davidson, went to Sobral, a town in the north of Brazil; the other, comprising Eddington and E. T. Cottingham, went to Principe, a small island off the west coast of Africa. The present group of letters, written by Eddington to his mother and sister, contains an account of his part in the latter expedition.

The four observers left Liverpool together aboard the steamship Anselm on 8 March and arrived at Madeira on the 12th, where they parted. Crommelin and Davidson went on to Brazil aboard the Anselm, while Eddington and Davidson were obliged to stay at Madeira till 9 April, when they recommenced their journey aboard the Portugal. They arrived at S. Antonio in Principe on the 23rd. After inspecting various possible sites on the island, they settled on Roça Sundy, the headquarters of a plantation owned by Senhor Carneiro, and their baggage was transported there on the 28th. They spent a week preparing the equipment, before returning to S. Antonio for the week 6–13 May; they then went back to Sundy to continue their preparations. The eclipse took place on 29 May. On 12 June the observers left Principe on the steamship Zaire. After changing ships at Lisbon, they arrived at Liverpool on 14 July. A report of the expeditions was communicated to the Royal Society on 30 October and printed the following year (Phil. Trans. A, ccxx (1920), 291–333). A draft by Eddington of the part of the report relating to the Principe expedition will be found at C1/3.

Letter from John W. Graham to Sarah Ann Eddington


Dalton Hall, Victoria Park, Manchester

2. VII. ’99

Dear Mrs. Eddington,

You will be interested in hearing some details of Stanley’s Preliminary. They are astonishing enough.—I have heard them today from the Chairman of the Board of Studies. In

Mechanics. Full marks
Latin. Top of all
Eng History [ditto]
Mathematics [ditto] & 60 marks above everybody else

leaving Chemistry & Eng. Language as the only subjects in which any one excelled him.

This is a marvellous record; whether he ought to know it I leave to you.

The great thing now is not to overload him; and to keep up his exercise: but I see no danger of going wrong in either respect.

In Physics ii at Easter I find he got 99 per cent. in the College Examination, making 199 out of 200. He has half the prize in Latin, the Prize in Practical Physics as well as theoretical; and the 2nd place in Math iii. A.

He will now, I trust, go in for a good physical athletic holiday. With my hearty congratulations

I remain
Yours sincerely
J. W. Graham

Letter from John W. Graham to Sarah Ann Eddington


Grand Hôtel des Bergues, Genève
3. Jan 1898.

Dear Mrs. Eddington,

I sent you just one bit of my ideas abt. Stanley as soon as he left us. The rest must follow now.

His presence has been a great pleasure to us. You have got a boy mixed of most kindly elements, as perhaps Shakspeare might say {1}. His rapidly and clearly working mind has not in the least spoiled his character. I don’t know when I have had to do with so modest and gentlemanly a boy. It is a testimony to day schools and home training, (not, I am afraid, my favourite theory.)

His youth has, of course, been just a little against his making friends, but has not been fatal to it. In Clayton, & in Wood & Brown he has nice associates; but he seems more contented alone than most boys are.

His work is all that I expected, & more: & I feel altogether that he is “a precious youth” committed to my charge. I can realise to some extent what Margaret would feel like if she were left alone to bring up our own little Richard.

I remain
Your friend sincerely
John W. Graham


The writing-paper is engraved with illustrations of the hotel, etc. The year is wrong, as Eddington did not enter Owen’s College till October 1898 (see his Notebook).

{1} {1} Graham evidently had in mind Antony’s encomium on Brutus at the end of Julius Caesar: ‘His life was gentle, and the elements | So mix’d in him that Nature might stand up | And say to all the world “This was a man!”’

Letter from John W. Graham to Sarah Ann Eddington


Meadow Brow, Grasmere.
VIII. ’02

Dear Mrs. Eddington,

My last duty is now one of simple good wishes.

The men up for Physics Hons. were a set much better than in any previous year. Any of the first three would have been top in any other year; & Stanley was well ahead of the others, & obtained over 80 per cent on the whole examination.

He will find a larger sphere and more competition at Cambridge; and I trust we shall hear he is bearing himself well under it.

With best wishes
I remain
Your friend sincerely
John W Graham

Letter from Arthur Schuster to A. S. Eddington


Victoria Park, Manchester
Novr 9. 1909

Dear Mr Eddington,

May I ask you—in confidence—whether you consider yourself definitely fixed to “Astronomy” or whether you would at all consider a return to Physics as possible.—I am not at liberty to go into details but the question arises whether in case a chair of Theoretical Physics were founded here or elsewhere and suitable conditions were offered you would be prepared to accept the chair.—Also in that case it might help matters if you wd let me know what conditions you would consider acceptable.

You may take it for granted that the duties wd leave you plenty of time for private work and that nothing wd prevent you continuing to prosecute the line of research on which you have entered with such success

I remain
Yours sincerely
Arthur Schuster.

Letter from A. S. Eddington to Winifred Eddington


Roça Sundy | Principe
May 5.

My dear Winifred

We are pretty well advanced in our work of erection and are taking a holiday today so I may as well start a letter to you. It seems ages since I started off in a rush in the taxi from the Observatory, and as I have only got Mother’s letter of March 14 as yet I do not know what has been happening to you for a long while—indeed I do not know what has been happening in the world in general—whether peace has been signed or any important events have occurred. I hope Punch is well and getting some walks, wish him many happy returns of his birthday from me; I expect you will not get this much before that event.

It was awfully nice having nearly four weeks in Madeira. I do not think the delay made much difference to us; if we could have gone on at once and reached here a month earlier we could have got some check photographs, though it would have been a rush getting the instruments ready in time. Failing that, there was not much object in arriving here earlier; and as things here have been managed very expeditiously, we are now making time for a week.

Cottingham & I get along very well, and I find him a very useful companion and good company. He is just 50, so, of course, is not fond of very much exercise, and generally preferred pottering round in Madeira and talking to the people; so I sometimes went off alone. For our last ten days I was very glad to find a more active companion in Geoffrey Turner, a very jolly boy keen on butterflies, on swimming and on chess, so we had several common interests.

I expect Mother sends on my letters to some of our relatives, so I did not mention in them, that I played roulette, of course not seriously, but enough to get a good idea of it and experience the ups and downs of fortune. I lost, like almost everyone else does, chiefly at the beginning, and then had pretty even fortune. I was about a £1 down, when I stopped; but I could not grudge it them, as it lasted for a number of afternoons’ play, to say nothing of the fact that I used the grounds of the Casino and had a very good & cheap tea there most afternoons during my stay.

It was a good thing to have some time at Madeira, because one got accustomed to hot weather. Out here the thermometer keeps steady at about 80° day and night; but one scarcely realises it is so hot. The evenings feel quite cool and refreshing. We have to wear sun-helmets out of doors almost always.

The ‘Portugal’ was a fairly good boat; but there were no games or facilities for exercise like on most boats, and (what surprised me very much) no deck-chairs for hire. Apparently they expected people to bring their own chairs. The time seemed to pass rather slowly, and even I was glad when we came to the end of the voyage. Of course the English and Portuguese did not mix very much; but we played games with them sometimes, and I think were quite popular on that account because the English usually keep aloof. We had “rings on the string” and “musical chairs” one afternoon.

The Portuguese here are a very superior type to those we have met before—in particular, they do not spit about all the time, and suck toothpicks at meals. Mr Carneiro is I believe very wealthy; he was going to Lisbon early this month, but postponed going especially in order to entertain us. No one speaks more than a few words of English except the two negroes Lewis & Wright, and in S. Antonio conversation is fragmentary because our friends there do not know French either. But here Mr Atalia and I plunge recklessly into very bad French, and can talk freely. Cottingham does not speak any French.

I wonder if you are still rationed. It seemed funny on the boat at starting to see full sugar-basins, unlimited butter, and to eat in a day about as much meat as would have been a week’s ration. We have had no scarcity of anything since we started. I have, however, scarcely tasted ham or bacon (eggs have been plentiful). The milk was not good on the Portugal, and I have got into the habit of taking tea without milk, which is the usual Portuguese custom & is probably better in hot climates. I cannot get any swimming here, because of the sharks.

There are several dogs about here, one of them rather a nice terrier; but for the most part they are not up to much. Nipper the dog at the hotel attached himself to me very much and followed me almost everywhere, although I did not encourage him at all, as he was neither beautiful nor free from fleas. He used to like to come and spend hours hunting lizards whilst we bathed.

It gets dark here about 6 o’clock, and as one does not sit much inside the house, one does not want to stay up long. I am usually quite ready for bed by half-past eight!

Please give my kind regards to Mr Green. I hope he is getting on alright. I think I shall be back home not much later than the middle of July.

With much love from
your affectionate brother

[Added at the head:] [I send {1} a letter to mother a few days ago which will probably arrive by same mail. This letter assumes you have read hers.] {2}


Three passages have been marked off in pencil by a later hand.

{1} A slip for ‘sent’.

{2} The square brackets are in the MS.

Letter from A. S. Eddington to Sarah Ann Eddington


1912 Sept 6
R.M.S.P. Arlanza {1}

My very dear Mother

There is an unexpected opportunity of sending a letter today, as we are calling at St Vincent to obtain a supply of fresh water; we could not get it at Madeira. After that it is no good writing until we reach Rio.

Last time I wrote was just after leaving Lisbon, since then we have had very pleasant weather, little wind, calm sea, sky rather overcast but with sunshine filtering through, and not unpleasantly warm, although we entered the tropics last night. We had a day at sea on Tuesday and reached Madeira about 11 the next morning. As we approached we passed a great many islands. Madeira is rather mountainous but a layer of clouds about some 3000 feet above the sea just cut their tops off, and remained all day. We were soon surrounded by lots of small boats selling basket chairs & embroidery—the two main products of Madeira—; also small boys wanting to dive for sixpences, some of them climbed to our highest decks and dived from there.

We had about 4 hours at Madeira and most of us did the regular excursion. Atkinson & Davidson did not come; but I went with the Unwins and Lady Grant. First we rode in chariots (there is no other word for them) drawn by a pair of bullocks[.] The streets are all cobbles and the vehicles are on wooden runners like sleighs; the bullocks gallop along finely. Then we went up the mountain Terreira da Lucca in a funicular railway, not quite to the top but 3300 feet up. The town (Funchal) is built in terraces on a steep slope. The abundance of vines laden with grapes was very remarkable, they grow on low pergolas. There were sugar canes[,] bamboos, palms, and beautiful blue hydrangias growing luxuriantly. Towards the top it was all pine forest. Just below the terminus we ran into cloud so lost the view; but as we had a fine view of the bay nearly all the way up, it did not so much matter. We had lunch at the top, and then came the exciting part—we tobogganed down the whole 3300 feet. There is a steep zigzag cobbled path down from the summit passing through the town; we go in a sort of basket toboggan holding 3 passengers, with with† two men running on each side with ropes to guide the toboggan and hold it back where necessary. They go at a great pace, {2} sometimes getting on and riding behind. It was much more exciting and alarming than I expected. We took about half-an-hour to get down. The sharp corners are particular[ly] exciting at first, because they always get up as much speed as possible to go round them (I suppose because swinging round checks the toboggan). After that came another bullock drive through the town to the launch, and so back to the steamer.

Now we have got to the main part of the journey, and shall be a week or more without any chance of landing. They are arranging some sports and I have entered for some of them. Atkinson is in for the tug of war and should be a tower of strength (and weight) for the “married” v “single”.

Captain Pope has been down to dinner twice, and is very pleasant and chatty. We are generally in the dining room half an hour longer than any-one else.

Tomorrow there is to be a celebration of the Anniversary of the Independence of Brazil. A Brazilian committee are arranging it.

I have not got much work done yet.

With very dear love,
ever your affectionate son


Letter-head of the Royal Mail Steam Packet Company. Numbered ‘2’ at the head in pencil.

{1} ‘R.M.S.P.’ is printed.

{2} Comma added in pencil.

† Sic.

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