| Description | ' The Committee met at the rooms of the Royal Astronomical Society at 11.30 am.
Present: Sir Frank Dyson in the Chair; Sir William Christie; Dr Crommelin; Professor Eddington; Admiral Field; Mr Jones; Mr Knobel; Mr Clean; Mr Maunder; Professor Newall; Professor Turner; Professor Fowler, Secretary.
Mr Davidson attended the meeting on the invitation of the Chairman.
The minutes of the preceding meeting were read and confirmed.
The following report of the Sub-Committee was read by the Society;
The Sub-Committee met twice during the early part of the year to complete the arrangements for observations of the Total Eclipse of 1919 May 29 at Principe and Sobral. In view of the uncertainties as to the cost of travelling and maintenace, and in consideration of the actual expenditure in preparation for the Expeditions, application was made to the Government Grant committee for a further sum of £250. This application was acceded to, bringing the total Grant to £1350.
The accounts relating to the expeditions to Principe and Sobral were presented by the Secretary and copies of the following summary were laid on the table;
Observing Huts ... £114-12-11
Instruments ... £23-18-4
Photographic Apparatus and Materials ... £56-1-10
Sundry Apparatus ... £7-1-2
Carriage of Instruments ... £60-4-6
Insurance ... £75-14-8
Travelling Expenses, Brazil ... £248-4-4
Travelling Expenses Principe ... £272-1-2
Maintenance, Brazil ... £193-10-0
Maintenance, Principe ... £45-19-2
Local Labour, Brazil ... £0-10-0
Telegrams and postage ... £19-13-11
Total; £1117-12-00
Government Grant; £1350-0-0
Balance; £232-8-0
Details of the Expenditure were explained by the Chairman and by the Observers, and the claim of the Sobral observers for maintenance at the rate of 20 shillings per day whilst on land, and 5 shillings per day when at sea, was approved by the Committee. The Chairman and Secretary were authorised to deal with outstanding small bills, if any, and to forward the accounts to the Government Grant Committee.
In view of the importance of the results obtained during the recent Eclipse, the Chairman drew attention to the desirability of making adequate copies of one or more of the negatives generally available for study. It was resolved that strong representations should be made to the Royal Society as to the desirability of distributing photographic prints with the published accounts of the observations; or, alternatively, that a reproduction should be included in the published paper, and that the Committee should be permitted to use some of the unexpended balance in preparing photgraphic copies for distribution to certain Astronomers and Institutions.
The Eclipse of 1922 September 20 was taken into consideration. The Chairman pointed out that the Eclipse was one of long duration, and expressed the opinion that if equatorial mountings were available it would be possible to photograph stars in the neighbourhood of the Sun on that occasion. After some discussion it was resolved that an application be made forthwith to the Government Grant Committee for the sum of £200, in order that the construction, or adaption, of equatorial mountings suitable for eclipse expeditions might be commenced at once.
It was resolved that the President of the Royal Society be requested to send a letter of thanks to the Brazilian Government and to the Administrator of Principe, for thre generous assistance which had been rendered to the Sobral and Principe Expeditions.
The Chairman was requested to send letters of thanks to Dr Morize, Director of the National Observatory at Rio, Dr Jacome de Oliveira, Prefect of Sobral, and Sir Jeronyme Cuneiro of Principe.
The Annual Report of the Committee was read, and aapproved, and ordered to be sent to the Royal and Royal Astronmical Societies.
Annual Report for the year ending November 30th, 1919
The Committee met once and a Sub-Committee twice during the year.
In accordance with the arrangements previously reported, two expeditions were sent out to secure observations of the Total Eclipse of May 29th, 1919, for the special purpose of investigating the possible deflections of rays of light by the Sun's gravitational field.
Dr Crommelin and Mr Davidson observed the Eclipse under favourable conditions in Brazil, and obtained two series of photographs, one with the astrographic telescope, and another with a 4 inch lens on 19 feet focus. The astrographic plates were not satisfactory in definition, on account of the distortion of the Coelostat mirror, but the second series of 7 plates was very good. The observers remained in Brazil until the end of July, in order to obtain check plates of the field of stars which surrounded the Sun at the time of Eclipse.
At Principe, near the West Coast of Africa, where Professor Eddington and Mr Cottingham were stationed, the eclipse was partially obscured by clouds, but a few photographs of value were obtained.
The results of the observations were presented to a joint meeting of the Royal and Royal Astronomical Societies on November 6th. The measurements of the plates have led to the conclusion that the deflection of 1".75 at the Sun's limb predicted by Einstein's generalised theory of relativity is verified by the Eclipse observations.
The thanks of the Committee are due to the Brazilian Government and to the Administrator of Principe for much valuable assistance annd generous hospitalilt.
[Signed] F W Dyson
1920 March 12 ' |