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LXIII. Notices respecting New Books. 

 Die Optilc cler elelctrischen Schwingungen. By A. Rig hi, Professor 

 of Physics in the University of Bologna. Translated into German 

 by B. Dessau, Privatdocent in the University of Bologna. 

 Leipsic, 0. E. Eeisland, 1898. 

 rpilE object of Professor Eighi in writing this treatise on electric 

 -■- waves was principally to set forth the experimental evidence 

 of their identity with light waves. After a preliminary section, 

 devoted to a description of the apparatus used in producing and 

 detecting electric oscillations, he gives an account of the phenomena 

 of interference, diffraction, reflexion, refraction, and polarization 

 exhibited by the waves, in each case pointing out the analogy 

 between the visible and the electric waves. The author has done 

 excellent work in this field of research, and many of the experi- 

 mental arrangements described are those which he has found 

 most satisfactory, while the experiments on elliptic polarization 

 and double refraction of electric waves, and the comparison of 

 their results with optical theory, are almost entirely his own work. 

 The present translation contains an account of two papers pub- 

 lished since the issue of the Italian original, the subjects being 

 the principal refractive indices of gypsum for electromagnetic 

 waves, and the orientation of a selenite disk in a uniform elecl/ric 

 field. The translator has had the advantage of access to the 

 author's apparatus, and of conference with him ; he has thus been 

 able to avoid many of the ambiguities frequently occurring in 

 descriptions of experimental work when the translator has not 

 witnessed the experiments which he describes. To those who find 

 difficulties with the Italian language the present volume may 

 prove a useful introduction to Professor Eighi's work. J.L.H. 



Skertchhfs Geology, revised by James Monckman, D.Sc. Ninth 



Edition. Pages viii and 256, with numerous Illustrations. 



Small 8vo. Murby : London, 1898. Price Is. 6d. 



Mr. Sydney B. J. Skertchly originated this little book on Geology 

 more than twenty years ago, when he was one of H.M. Geological 

 Surveyors. He was impressed w^ith the necessity of teaching that 

 the earth is an integral part of the universe, and that its past and 

 present condilions have resulted from the action of heat upon 

 matter in its different states. Hence the leading idea of this work 

 is that all geological agencies can be resolved into heat ; and that 

 the origin of the Earth itself, of the rocks which constitute it, and 

 of the forms which the surface presents, are all either due to, or 

 have been influenced by hear, either internal or external. 



With these principles in view, there is a continuous line of 

 thought, and a well-linked chain of facts and notions, connecting 

 the scientific details in the history of the Earth and the description 

 of its structure and conditions. Its inhabitants, too, of all kinds, 

 both in past and present ages, have been vitally affected by the 

 Earth's caloric, how T ever distributed in time and place. " This 

 work therefore traces the history of the evolution of the Earth 

 inductively, and assigns to Geology its true place as a branch of 

 celestial kinetics, .... and places the subject in the light of a 

 living science, instead of a collection of dry details concerning 

 rocks and their contents." 



With the foregoing reasons for the classification of its subject- 



