22 



SCIENCE 



[N. S. Vol. LIII. No. 1358 



came to try to determine the angular diameter 

 of stars they were up against a very much 

 more difficult problem. I knew that they were 

 working on these lines, but this is the first 

 word I have heard of the results. 



" At a meeting of the British Association I 

 delivered a presidential address to the mathe- 

 matical and physical sections, and made refer- 

 ence to the fact that this experiment which was 

 being carried out would be of the very greatest 

 importance. We have of course had theories, 

 and, working on those theories, I gave a table 

 of what I thought would be the angular diam- 

 eter of certain stars, and I am delighted to find 

 that the figures so nearly correspond. This 

 would seem to show the theories have been on 

 the right side. 



" In particular, I noticed that Betelguese's 

 diameter is 260,000,000 miles, which is enor- 

 mously larger than the sun. That is a very in- 

 teresting confirmation of the theory of Russell 

 and Hertzsprung of giant and dwarf stars, giv- 

 ing direct evidence that Betelguese is one of 

 the inflated stars and very different from the 

 sun." 



Dr. A. C. Crommelin, chief of staff of the 

 Greenwich Observatory, was interviewed to- 

 day on Professor Michelson's discovery by The 

 Evening Standard and expressed the interest 

 the experts in England's principal observatory 

 took in it. 



" Star diameters have been calculated 

 hitherto," he said, " but have never before been 

 actually measured. Michelson's announcement 

 that he has measured Alpha Orionis and found 

 it to have a diameter of 260,000,000 miles, 300 

 times bigger than the sun, is hopeful. 



"That the distance from the earth of such a 

 star as Alpha Orionis, which is 900,000,000,- 

 000,000 miles away, should have been measured 

 so long ago and the size of the star should re- 

 main unmeasured seems strange, but it was 

 explained at the offices of the Royal Astronom- 

 ical Society that the two measurements have 

 to proceed on entirely diiierent lines. 



" The Astronomical Society confirms Dr. 

 Crommelin in the expectation of good results 

 from Professor Michelson's work. For some 

 time past he and his work have loomed increas- 



ingly large in the astronomical world. — Cable- 

 gram to the New York Times. 



CAUSES OF CLIMATIC OSCILLATIONS 



IN PREHISTORIC TIME, PARTICU- 

 LARLY IN THE ICE AGEi 



In 1918 Professor Arldt, of Radeberg, 

 grouped the theories and weighed the evi- 

 dence which had been proposed by 117 scien- 

 tists in the past si;xty years on the causes 

 of the glacial and interglacial epochs. As 

 none of these hypotheses are in all respects 

 satisfactory, in his opinion, or can claim to 

 explain thoroughly all paleo-climatic phe- 

 nomena, he does not recognize any one theory 

 or group of them. This is not surprising 

 since the fundamental conclusions underlying 

 these hypothesis have not been reached. 



In this paper of twenty-seven pages, Arldt 

 does not give an exhaustive explanation of the 

 numerous hypotheses which have been pro- 

 posed but a brief statement concerning the 

 most important groups among them. He dis- 

 tinguishes two classes. Cosmic and Telluric, 

 with three subdivisions for the first: Univer- 

 sal, Solar and Telluro-Cosmic ; and five for 

 the second: Dislocation of the Poles, Atmos- 

 pheric, Intra-Telluric, Aetologic and Oro- 

 graphic. Although discussions and opinions 

 are to be found under each of these headings, 

 his main contribution appears in crystallized 

 but abbreviated form in his conclusion, thus: 



Among numerous theories explaining the 

 changes in climate of the earth, those should be 

 given preference which are based upon the hy- 

 pothesis that the factors which are of importance 

 to-day in determining climate have always been 

 effective. . . . Most importance is attached to 

 Ramsay's theory which emphasizes most strongly 

 the direct and indirect action of the mountains. 

 Besides these orogenetic forces other elements, as 

 enumerated below, probably aided in the genera- 

 tion of the ice ages. 



1. The rise of extensive mountains (Eamsay). 



2. The formation of ocean basins (Arldt). 



3. The sinking of the entire ocean floor and the 



1 Theodore Arldt, ' ' Die Ursaehen der Klimasch- 

 wankungen der Vorzeit, besonders der Eiszeiten, " 

 Zeitschrift fur Gletscherkunde, Band XI., s. 1-27, 

 1918. 



