5 68 



NA TURE 



[October 28, 1922 



it was found that the swallows, as a group, possess the 

 lowest average body temperature. In seven species 

 examined in this family one alone, the rough-winged 

 swallow (Stelgidopteryx serripennis), showed an average 

 greater than 107-5 F. Humming birds also, "with 

 their tiny bodies seem to have a considerable range in 

 temperature, but as a whole fall low in body warmth." 

 The volume is an important monograph, containing 

 much valuable data, and it is a noteworthy contribu- 

 tion to this field of avian physiology. 



Sutherland Simpson. 



Prof. Eddington's Romanes Lecture. 



Pour comprendre Einstein. Par l'Abbe Th. Moreux. 



Pp. 245. (Paris : G. Doin, 1922.) 7 francs. 

 Die Grundlagen der einstein' schen Relativitatstheorie : 



Eine kritische Untersuchung. Von Prof. Dr. II. 



Strasser. Pp.no. (Bern: Paul Haupt, 1922.) n.p. 

 Philosophy and the Neie Physics : An Essay on the 



Relativity Theory and the Theory oj Quanta. By Prof. 



Louis Rougier. Authorised translation from the 



author's corrected text ol " La Materialisation de 



l'energie." by Prof. Morton Masius. Pp. xv+159. 



(London : G. Routledge and Sons. Ltd., n.d.) 6s. 



net. 

 Le Principt de la relativiti el les theories d'Einstein. 



Par Prof. L.-G. du Pasquier. Pp. xvi + 511. (Paris : 



G. Doin. 1022.) r8 francs net. 

 Le Principe de la relativiti et la thtorie d'Einstein. Par 



Dr. Leon Bloch. (Bibliotheque des Annales des 



Posies. Telegraphes et Telephones.) Pp. iii + 42. 



(Paris : Gauthier-Villars et Cie, 1022.1 3.50 francs. 

 The Romanes Lecture, 1922. The Theory oj Relativity 



and its Influence on Scientific Thought. Delivered in 



the Sheldonian Theatre. May 24. 1922. Py Prof. 



A. S. Eddington. Pp. 32. (Oxford : Clarendon 



Press. 1922.) 25. net. 



ANOTHER collection of books and pamphlets 

 reminds us of the hold which the theory of 

 relativity has on the public imagination. 



The Abbe Moreux gives his book the title " Pour 

 comprendre Einstein," though he seems to consider 

 that the effort to understand him is so much waste of 

 time, for in his view the theory is both superfluous 

 and misleading. Dr. Strasser. an anatomist with an 

 amateur's interest in physics, gives us a critical dis- 

 cussion of the theory, but it is manifest that he has not 

 come near to understanding it. Prof. Rougier, a philo- 

 sopher who has read all about the new physics, sets 

 out to tell us something of the influence of the theory 

 upon philosophy, but leaves us with the impression of 

 a shallow and ill-digested understanding of the ile\ elop 



NO. 2765, VOL. I IO] 



ment of physical science and tells us little about 

 philosophy. Prof, du Pasquier and Dr. L. Bloch are 

 less ambitious in their aims ; they are content to be 

 expositors and not critics. The results are correspond- 

 ingly more successful and will probably lie very useful 

 to the French reader. 



But among the books before us, the English reader 

 naturally turns to Prof. Eddington's Romanes Lecture 

 to hear the latest thoughts of one who has done more 

 than any man living to establish and to popularise the 

 general theory of relativity. 



The lecturer impresses it upon his audience that it 

 is stale news that the events around us form a world 

 of four dimensions. There is, however, something that 

 is new. It used to be customary for us to think of 

 this four-dimensional world as having a definite set of 

 sections, any one of which represented the state of the 

 universe at a particular moment of absolute time, the 

 whole being thus stratified in recognisable Ia\ers. But 

 now this stratification has disappeared, there are no 

 absolute time sections ; it is only the individual 

 observer who, to meet his own convenience, dissects 

 the whole into " rashers," labelling each with the mark 

 of an instant ol his own consciousness. With a wealth 

 of illustration and with language both grave and _a\ 

 Prof. Eddington seeks to cure us of our egoistic out- 

 look, and to persuade us to the wider view which finds 

 truth, not in a particular picture of reality seen from 

 one angle, but in a vision which includes and com- 

 prehends every possible picture. "It is only in this 

 undissected combination of four dimensions that the 

 experiences of all observers meet." On this we need 

 scarcely dwell here, save to remind ourselves that the 

 fault from which he would save us is one to which men 

 in all ages have been prone, and not the least sinners 

 have been those whose profession was the pursuit of 

 exact truth. Yet we cannot help feeling that at times 

 tlie preai her goes too far and so damages his case. To 

 quote an illustration from the lecture. We allow an 

 apple to fall. The moment the apple is released the 

 earth begins to rush up to meet it. This is " the 

 apple's view of things." " It is simpler than Newton's. 

 We should regard it as on an equal footing with that 

 of a terrestrial observer." This is very like asking an 

 engine-driver to admit that it is quite natural to con- 

 sider that when he admits the steam to the cylinder he 

 sets not the engine but the whole universe in motion. 



This is trifling however. Let us return to our 

 destratified world of four dimensions. If we have been 

 able to achieve this vision or to conceive oi its possi- 

 bility, we have grasped the essence of the doctrine of 

 relativity, and we have come near to a superhuman 

 view of history. The world is laid out before us as 

 a changeless whole. Time and space are no more. 



