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consequences, to modify it if necessary, and to abandon it should observation 

 disprove it. He recalled the hostility aroused at first by Maxwell's electro- 

 magnetic theory of light, and mentioned how loth Lord Kelvin had been to accept 

 it : he still continued to attempt to explain the aether by attributing to it properties 

 similar to those of ordinary matter. As in that case, so now it must be left to the 

 younger generation to discuss and analyse the new theory. 



Einstein en his Theory (H. S. J.) 



The Times of November 28 contains an article by Einstein on his theory. 

 The following extracts contain the more salient points : 



" The laws according to which material bodies are arranged in space do not 

 exactly agree with the laws of space prescribed by the Euclidean geometry of 

 solids. This is what is meant by the phrase ' a warp in space.' The fundamental 

 concepts 'straight,' ' plane,' etc., accordingly lose their exact meaning in physics. 



" In the generalised theory of relativity, the doctrine of space and time, 

 kinematics, is no longer one of the absolute foundations of general physics. The 

 geometrical states of bodies and the rates of clocks depend in the first place on 

 their gravitational fields, which again are produced by the material systems 

 concerned. 



" Thus the new theory of gravitation diverges widely from that of Newton with 

 respect to its basic principle. But in practical application the two agree so closely 

 that it has been difficult to find cases in which the actual difference could be 

 subjected to observation. . . . 



" The great attraction of the theory is its logical consistency. If any deduc- 

 tion from it should prove untenable, it must be given up. A modification of it 

 seems impossible without destruction of the whole." 



The last paragraph is of particular importance as giving Einstein's own view 

 as to the inter-relationship of the various predictions of the theory. In particular 

 it indicates that, should the negative spectroscopic result be definitely established, 

 the theory — in spite of its other successes — could not be maintained. 



In conflict with this view, Sir Joseph Larmor, in a paper presented to the 

 Royal Society on November 20, states that no spectral displacements should be 

 expected. This paper is not yet published, and the writer has only seen the 

 meeting abstract, so that the ground on which this conclusion is based cannot be 

 examined. 



The Solar Eclipse Expeditions and their Results (G. B. J.) 



A joint meeting of the Royal Society and the Royal Astronomical Society 

 was held on November 6 to discuss the results of the observations obtained at 

 the total eclipse of the sun on May 6, 1919. 



It will be remembered that, according to Einstein's generalised theory of 

 relativity, the light coming from a distant star is deflected inwards by the 

 gravitational field of the sun by an amount which increases with the proximity 

 of the light ray to the sun's centre. Another theory, which in effect regards 

 light as corpuscles subject to the ordinary Newtonian laws, gives a similar 

 result, but the deflection of the ray is only one-half that predicted by Einstein's 

 theory. In order to decide between these rival theories two expeditions were 

 sent out to observe the total eclipse of the sun on May 29, 1919 ; one to Sobral 

 in North Brazil, in charge of Dr. Crommelin and Mr. Davidson, and the other 



