Maech 26, 1920] 



SCIENCE 



305 



Abbot, of The Smithsonian Institution, at La 

 Paz, Bolivia; H. Morize, in charge of the 

 Eio de Janeiro Observatory party at Sobral, 

 Brazil; the British Astronomical Party (0. 

 Davidson and A. 0. D. Crommelin) at Sobral; 

 L. A. Bauer at Cape Palmas, Liberia; and the 

 British Astronomical Party (A. S. Edding- 

 ton and Mr. Cottingham) at the lie of Prin- 

 cipe in the Bight of Africa. Also slides of 

 the great solar prominence of May 29, 1919, 

 as photographed at the Yerkes Observatory, 

 were exhibited. Grateful acknowledgement is 

 here made to the Astronomer Eoyal of Eng- 

 land, Sir Frank W. Dyson, and to those just 

 mentioned, for copies of the photographs 

 taken by their expeditions, as also to Dr. 

 W. W. Campbell, who supplied slides showing 

 how the corona changes its shape during the 

 sun-si)ot cycle. 



11. The chief features of the solar corona 

 and prominence, as shown by the series of 

 slides exhibited, have already been stated in 

 paragraphs six and seven, where the observa- 

 tions at Cape Palmas were described. Care- 

 ful measurements have been made between the 

 various prominent features, as shown on the 

 photographs taken along the belt of totality 

 from Bolivia to the French Congo. From all 

 the data supplied it is found that the mean 

 heliographic latitude of the prominence dur- 

 ing the time of the eclipse was about 18° 

 south, and on the east limb, whereas the pro- 

 nounced V-rift was about 45° south, and on 

 the west limb. Practically diametrically op- 

 posite the V-rift was a less-pronounced rift, 

 which I have called the U-rift. The solar 

 prominence during the average time (11H8" 

 G.M.T., civil) of totality at the two South 

 American stations and the average time els'* 

 55™ G.M.T., civil) of the two African stations 

 changed comparatively little, though later in 

 the day, according to the Yerkes Observatory 

 photographs, kindly supplied by Professor 

 Frost and Mr. E. Pettit, very great changes 

 took place; thus, for example, at 20'>23'" 

 G.MT., civil, the prominence had shot up to 

 the height of 472,000 miles from the sun's 

 limb.® 



8 See Mr. Edison Pettit 's aeooiant in the Astro- 

 ■physicaX Journal, for Ootober, 1919, pp. 206-219. 



12. A distinct purpose was had in mind in 

 exhibiting first the various features of the 

 solar corona and prominence, which persisted 

 for four rotations of the snn and filled por- 

 tions of the solar atmosphere with the prod- 

 ucts of eruptions, in order that one might be 

 the better prepared to pass judgment upon 

 the results concerning the deflection of light 

 rays. For the same reason was given an ac- 

 count, though incomplete, of the results of 

 our geophysical observations. "We shall find 

 that all the various phenomena though appar- 

 ently unrelated have, indeed, an important 

 bearing upon our next topic. 



13. Altogether the solar eclipse of May 29, 

 1919, as observed at Cape Palmas, Liberia, 

 was the most magnificent one of the four^ it 

 has been my good fortune to observe. Sim- 

 ilarly Dr. Abbot with reference to what he 

 saw at La Paz, Bolivia, saysi^" 



Taking into aeemint tihe great length and beauty 

 of the ooronal streamers, the splendid crimson 

 prominence throwing its glory over all, and the 

 fact that the eclipse was observed so near sunrise 

 from so great an eleva<tion as 14,000 feet, with a 

 snow-covered range of mountains upwards of 20,- 

 000 feet high as a background for the phenomenon. 

 it seemed to the observers to be the grandest eclipse 

 phenomenon whieh they had ever seen. 



RESULTS OF OBSERVATIONS FOR DEFLECTION OF 

 LIGHT 



14. The most important result, undoubtedly, 

 of the observations made by the astronomical 

 parties during the solar eclipse of May 29, 

 1919, is the disclosing of the fact that the 

 rays of light coming from stars, which ap- 

 peared on photographs taken of the eclipsed 

 Sim. and surrounding region, were bent by a 

 measurable amount. ISTo matter what the 

 cause of the bending actually was, the fact is 

 of profound interest and is bound to advance 

 our knowledge. The chief possible causes 

 which have been advanced thus far are : 



(a) Newton-Maxwell Effect. — Deflection of 

 the rays of light hy the sun's gravitational 



9 See footnote 2. 



10 Abbot, C. G., and A. F. Moore: "Observa- 

 tions of the Total Solar Eclipse for May 29, 1919, ' ' 

 Smithsonian CoUeotions, Vol. 71, No. 5, p. 3, 

 "Washington, January 31, 1920. 



