so 



DISCOVERY 



€xtra outpouring of energy from sunspots so affects the 

 earth's atmosphere as to make it stormier than usual, with 

 the consequence that the earth's surface is actually 

 cooled. In the past some of these disturbances in the 

 sun have been large, and the earth consequently so 

 affected by them that a glacial epoch has resulted ; at 

 other times and more frequently the disturbances have 

 been smaller, and parts of the earth, although profoundly 

 affected, have suffered less. These have been the 

 historical pulsations. More frequsnt still and of still less 

 force have been the disturbances said to occur every 

 thirty-three years and those more perfectly recognised as 

 occurring every eleven or twelve. 



It is the sunspots, the authors believe, which are the 

 fundamental cause of the variations in the earth's climate. 

 They bring about glacial periods, create oceans and 

 mountain ranges, and indeed affect our whole physical 

 environment. The arguments for this cannot be given 

 here. Readers interested in them will find them in the 

 book. 



The next question to be asked is : " What causes the 

 sunspots ? " That, indeed, is a difficult question. 

 Astronomers declare they do not know But Dr. Hunting- 

 ton and his colleague put forward a verj fertile hypothesis. 

 They believe that sunspots — disturbances in the sun's 

 atmosphere — are caused by the conjunction of the planets 

 as well as by the less regular but vastly more disturbing 

 influence of other stars wliich pass our solar system in 

 their journey through space. It is obvious that changes 

 in the energy emitted by the sun must be due either to 

 a source in the sun or to a source external to it. If it 

 be in the sun we are, so to speak, " done," because no 

 one at the present time can formulate in precise terms a 

 reason therefor ; but if the source be outside, we have 

 the whole universe in which to seek a likely cause. Now 

 Jupiter is the largest of the planets, and its changing 

 position with respect to the sun might affect the latter's 

 atmosphere in some way. This way is still open to 

 question, but ignorance of it need not affect the matter. 

 What is of significance is that Jupiter's period of revolution 

 round the sun, ii-86 years, is very nearly that of the 

 sunspot cycle. When, indeed, the effects of Jupiter, 

 Saturn, and the other planets are combined they produce 

 a highly variable curve which has an extraordinary 

 resemblance to the sunspot curve. Because of this the 

 authors accept this planetary hypothesis of sunspots and 

 proceed to develop it. It is known that the climatic 

 difference between sunspot maxima and minima, as 

 measured by temperature, amounts to at least a twentieth 

 and perhaps a tenth of the difference between the climate 

 of the last glacial epoch and the present. From this the 

 authors deduce that a body exerting only four times 

 Jupiter's present tidal effect and placed at the average 

 distance of Jupiter from the sun would so disturb the sun's 

 atmosphere as to make possible a glacial period over 

 the earth. 



It is clear that what Jupiter and the other planets may 

 do regularly in, so to speak, a humble way, may be done 

 on a larger scale at irregular intervals by the stars most 

 nearly encountered by the sun in its journey through 



space. The authors' theory is that a star may influence 

 the sun so ns to bring about climatic change on earth 

 in proportion to its size, temperature, and nearness to 

 the sun. The first two of these are fairly constant, but 

 since stars and the sun are moving relatively to each 

 other through space, the third varies. At most times 

 the distances of stars, although variable, are so immense 

 that it may be said the stars have no influence on the 

 sun at all, but there have been times (they can be worked 

 out from astronomical data) when the nearest have been 

 sufficiently near to have, on certain assumptions, a much 

 larger effect than the planets. These times the authors 

 connect with the times of great climatic changes. They 

 show that an average single star would influence the sun 

 enough to cause glaciation on the earth if it came within 

 two hundred thousand million miles of it. They show 

 too that if a Centauri, the nearest fixed star to the sun 

 and at present 4-4 light-years distant, came within 1-4 

 light-years it would produce a glacial epoch. From 

 existing astronomical data the influence of the proximity 

 of the stars to the sun on the climate of the earth can 

 be worked out, and in Chapter XV a cvirve is given 

 showing the climatic change of 140,000 years (from 

 68,000 B.C. to A.D. 72,000) so inferred. The curve shows 

 that 70,000 years ago the climate was extremely mild. 

 It gradually became severer, being 45,000 years ago 

 approximately what it is to-day, and became severest 

 about 28,000 years ago. (This agrees very well with the 

 time of the last glacial epoch, which the best authorities 

 put between 25,000 and 30,000 years ago.) The curve 

 shows an amelioration of climate since that time, although 

 it suggests that there is still considerable severity. If 

 we look forward to the 70,000 years ahead we see from the 

 curve that the climate will be, on the whole, very like 

 that of to-day. In that time there will be no return to 

 the very mild climate ; likewise there will be no glacial 

 epoch. 



These interesting speculations are being developed in 

 a book shortly to be published entitled Earth and Sun. 



A. S. Russell. 



Reviews of Books 



PROFESSOR BERCxSON'S ATTACK ON 

 INTELLECTUALISM 



The Misuse of Mind. By K.\rin Stephen. With a 

 prefatory letter by Henri Bergson. (Kegan Paul, 

 65. 6d.) 



The exposition of Professor Bergson's stimulating and 

 disconcerting pliilosophy is a matter of peculiar difficulty, 

 for he demands that we should put aside our old logical 

 modes of thought and take up a new attitude towards 

 reality, and since language itself was created by the old 

 modes of thought that we are asked to abandon, it follows 



