10 PRESIDENT'S ADDRESS. 



remain in equilibrium. If I clip my finger into a pond, it moves 

 every drop of water in that pond or only produces pressure 

 perhaps on some of them without actual motion ; but the whole 

 thing takes up a new position of equilibrium which might be 

 calculated for any one particle of water from Einstein's 

 equations. From this equation three special results were 

 calculated and prophesied. The first was a perturbation of 

 Mercury, a very slow rotation round the sun of the perihelion 

 of its orbit, which had long been known to Astronomers and 

 which gravitation did not appear to account for. Einstein's 

 theory shews such a movement. By the second calculation, 

 the ray of light coming from a star and passing close to the 

 sun should be bent by a minute angle, by the influence of the 

 sun. The total eclipse of May 29th last afforded the 

 opportunity of observing such a star, which would otherwise 

 be invisible owing to the sun's brightness, and an amount of 

 bending of its rays approximately equal to the calculated angle 

 was seen to exist. It is right to state that various other 

 explanations have been offered of this phenomenon, but 

 nothing very conclusive. The third calculation is, that for 

 light coming from the sun the positions of the minute lines in 

 the spectrum would be different from those produced by the 

 same sort of light generated on the earth. This has not been 

 borne out by experiments; but these are of a very delicate 

 nature (as indeed are all the tests), and I believe that the 

 question is not as yet considered to be settled. In regard to 

 other results of this eclipse, it was observed that wireless 

 signals, received in districts under the penumbra or partial 

 eclipse were strengthened, the short duration of totality at any 

 point not producing any further perceptible effect. A very 

 fine prominence was observed during the eclipse, which rose 

 to a height of more than half the sun's diameter at a rate of 

 something like 50,000 miles an hour. In the middle of 

 December last, six of the planets were within 26 of longitude, 

 this near grouping causing much excitement amongst astro- 

 logers and those who followed them. Some slight perturbations 

 of Neptune have brought up again the question of a planet 



