5. So 



NA TURE 



[Atril 16, 1903 



that certain red rocks passed through in a boring at 

 Knock-e-Dooney " are identical physically with those 

 which are exposed on the shore to the north-east of 

 Peel," while Lamplugh remarks of the same strata 

 that " they bear no resemblance .... to the Peel 

 rocks." 



As would be expected from his previous glacial work 

 the author has devoted particular attention to the 

 glacial drifts and other superficial deposits of the isle, 

 and in this portion of the book the writer is seen at his 

 best. His principal conclusions are confirmatory of 

 those of Kendall, whose work is fully acknowledged, 

 as, indeed, is the work of all previous writers on Manx 

 geology. He rejects the " submergence " hypothesis, 

 and traces the sequence of events from the gradual 

 formation of the ice-sheet through its various phases 

 to its final disappearance. The thickness of the ice 

 on the bed of the Irish Sea is estimated at not less 

 than 3000 feet. The phenomena that occurred during 

 the melting of the ice have been ably worked out, es- 

 pecially in the north of the island, where the formation 

 of glacial lakes with their overflows is clearly and con- 

 vincingly described. 



The full details given of the metalliferous deposits 

 should be valuable in connection with mining enter- 

 prises. The account of the igneous rocks is fairly 

 exhaustive, the petrological descriptions being in the 

 form of notes mainly from the pen of Prof. Watts. 

 Considering the space devoted to the descriptions, it is 

 a pity that the microscopic characters, especially the 

 structures of the rocks, are not illustrated by a plate 

 or a few text-figures. 



The volume bears evidence throughout of the author's 

 stratigraphical skill. His facts are well arranged and 

 clearly stated, and his conclusions carry confidence to 

 the reader's mind because there is no appearance of 

 any attempt to make the evidence prove more than the 

 facts will reasonably explain. C. A. M. 



MEMOIRS OF PHYSICS. 



Rapports prisenMs au Congres international de 

 Physique reitni a Paris en 1900. Edited by Ch, Ed. 

 Guillaume and L. Poincare. 4 vols. (Paris : 

 Gauthier-Villars, 1900.) 



WHEN the Societe Frangaise de Physique organised 

 its international congress on physics, at the 

 Paris Exhibition in 1900, it was the wish of several 

 members of the commission appointed for that purpose, 

 notably of their distinguished president, M. A. Cornu, 

 whose death we have since had occasion to deplore, that 

 a volume should be prepared which might survive the 

 reunion which gave it origin, and form a suitable record 

 of the same. This happy thought led to the request 

 that a number of investigators should give accounts of 

 their life works, showing the connections with 

 the results obtained by previous investigations, 

 and indicating probable advances in the future. 

 These investigators were asked to forget, for 

 the moment, the multitude of interesting details 

 involved in their researches, and to treat their re- 

 NO. 1746, VOL. 67] 



spective subjects from a general point of view. As a 

 consequence, we have before us a series of memoirs on 

 important branches of physics, each written by a 

 recognised authority, dealing with important and far- 

 reaching advances in physical science. The value of 

 these memoirs is greatly enhanced by full references 

 to original publications. 



In the first volume, amongst other important papers, 

 we may notice a paper on the precision of length 

 determinations, by J. Ren£ Benoit. This paper con- 

 tains an account of Prof. Michelson's standardisation 

 of the metre, in terms of the wave-length of light. An 

 interesting paper by P. Chappuis deals with practical 

 and theoretical scales of temperature, while J. S. Ames 

 contributes an article on the mechanical equivalent of 

 heat, and E. H. Griffiths adds an appendix on the 

 specific heat of water. 



To the general reader, vol. ii. will perhaps be found of 

 greatest interest. This volume deals with recent ad- 

 vances in optics, electricity, and magnetism; W. Wien 

 contributes an article on the theoretical laws of radia- 

 tion, which is followed by a paper on the radiation of 

 a black body, by O. Lummer, and another on the emis- 

 sion of light by gases, by E. Pringsheim. These three 

 papers form an excellent introduction to the recent ex- 

 tensions of thermodynamical methods to the theory of 

 radiation. Prof. Lebedevv gives an account of his ex- 

 perimental proof of the mechanical pressure of light, 

 while H. Rubens describes his investigations of 

 infra-red waves of great length. A paper by J. R. 

 Rydberg gives a brief account of the distribution of 

 lines in the spectra of the elements. This is a subject 

 which will probably be greatly extended in the future ; 

 it may very probably lead to a complete mechanical 

 theory of atomic structure, a domain into which the 

 researches of Lorentz and Zeeman have already given 

 us a glimpse. M. Cornu 's paper on the velocity of 

 light will be read with great interest, although it would 

 hardly appear that the author made out a very strong 

 casi against the researches of Michelson and Newcomb. 

 A paper on the electromagnetic theory, by J. H. Poyn- 

 ting, should be in the hands of all advanced students 

 of physics. These, together with the remaining 

 articles in vol. ii., render this of unusual interest. 



Vol. iii. contains papers on recently discovered 

 magneto-optic phenomena, by H. A. Lorentz ; the 

 theory of dispersion and metallic reflection, by P. 

 Drude ; and on radio-active substances, by H. Becquerel 

 and bv M. and Madame Curie. Prof. J. J. Thomson 

 considers the results of recent researches on the passage 

 of electricity through gases ; V. von Lang examines the 

 evidence as to the back E.M.F. of the electric arc, while 

 A. Potier contributes a very readable article on poly- 

 phase currents. C. V. Boys gives an account of the 

 various methods of determining the Newtonian con- 

 stant of gravitation, with an able criticism of the 

 various values obtained. 



The fourth volume contains the minutes of the con- 

 gress, a number of replies to criticisms and short com- 

 munications, and, finally, a list of names of the 

 members. E. E. 



