454 SCIENCE PROGRESS 



in the ecliptic to enable the same star-field to be photographed with the same 

 instruments and mountings as were used during the eclipse. In spite of the 

 unfavourable weather conditions at Principe, and some difficulties arising from 

 the heating of the coelostat mirror of the larger of the two instruments used at 

 Sobral, satisfactory photographs were obtained at both stations. On measure- 

 ment the plates provided conclusive evidence of a deflection of the star-images 

 away from the centre of the sun's disc. When reduced to its value at the sun's 

 limb the Sobral observations gave a mean deflection of \'gZ'\ while those at 

 Principe, which, owing to the adverse weather conditions, were regarded as less 

 conclusive, gave 1*64". The value predicted by Einstein's theory is 175", while 

 the Newtonian theory gives "875". It was therefore concluded that the observa- 

 tions confirmed the prediction of the former theory. 



After Sir F. W. Dyson, Prof. Eddington, and Dr. Crommelin had described 

 the work of the expedition and the methods adopted for the reduction of the 

 data, a discussion followed. Sir J. J. Thompson emphasised the importance 

 of the results obtained, which should be considered in connection with the 

 growing body of evidence in support of Einstein's theory. The deflection of 

 the ray of light implied a change in the direction of the electric and magnetic 

 vectors which, it seems, must be due to a new type of electric force. 



Prof. Newall urged the necessity for caution in the interpretation of the 

 established results of the observations, which might conceivably be due to other 

 causes, as, for instance, refraction in a solar atmosphere. 



Prof. Lindemann stated that the observed deflection, if due to refraction, 

 required a density of the solar atmosphere which was inadmissible on other 

 grounds. 



Dr. Silberstein contended that, regarded as a consequence of Einstein's 

 theory, the present problem was inseparable from another prediction of the same 

 theory — that the Fraunhofer lines of the solar spectrum will be displaced 

 towards the red. Hitherto observation has failed to establish any such dis- 

 placement, and so long as this is the case we cannot regard the present results 

 as establishing the basis of Einstein's theory. 



Report on the Proceedings of Section A, British Association, Bourne- 

 mouth, 1919. (Prof. A. 0. Rankine, D.Sc.) 



In spite of the absence of several eminent physicists who usually attend the 

 meetings, there was much of interest and importance in the proceedings of this 

 Section. A full programme occupied the four mornings from September 9-12, 

 commencing with the Presidential Address. Prof. A. Gray, after paying graceful 

 tributes to the memory of Carey Foster and Lord Rayleigh, criticised severely 

 the conduct of the war in its scientific aspect by the Government. That they 

 failed to utilise the special abilities of scientifically trained men from the Uni- 

 versities and Colleges, particularly in the early stages of hostilities, is notorious, 

 and to this failure Prof. Gray attributed largely the protraction of the war. The 

 remedy he suggests is the formation of a record of scientific graduates for special 

 service, and he believes that this should still be done, notwithstanding the cessa- 

 tion of the recent war, in order that we may be prepared against eventualities. 



Prof. Gray's next criticism was directed against the procedure with reference 

 to inventions during the war. Inventions which seemed likely to be of practical 

 importance often failed to be adopted by G.H.Q. because they were tested, and 



