Chemistry and Physics. 233 



Whethara deal with the building of the laboratory ; Professor 

 Schuster, with the Clerk Maxwell period ; Mr. Glazebrook, with 

 the years during which Lord Rayleigh was professor ; and Sir 

 J. J. Thomson, himself, gives a general survey of the past twenty- 

 five years. In chapters V to VIII the activities of the labora- 

 tory during these twenty-five years, are discussed in greater 

 detail. Professor Newall gives an account of the researches 

 conducted between 1885 and 1894 : Professor Rutherford recounts 

 the memorable achievements which marked the years 1895-1898 : 

 C. T. R. Wilson deals with the period from 1899 to 1902, and 

 N. R. Campbell completes the record to 1 909. Chapter IX by 

 Professor Wilberforce of the University of Liverpool deals with 

 the development of the teaching of physics in Cambridge, a 

 development which has had great influence upon physics teach- 

 ing throughout the world. The volume closes with a list of 

 memoirs containing accounts of research performed in the Caven- 

 dish Laboratory, and a list of those who have worked there. 



The volume cannot fail to be of great interest to all students 

 of physics ; it is a valuable contribution to the recent history of 

 the science, and a more appropriate way of celebrating Sir J. J. 

 Thomson's twenty-fifth anniversary could scarcely have been 

 found. H. A. B. 



7. The Principles and Methods of Geometrical Optics, espe- 

 cially as applied to the theory of Optical Instruments ,\ by 

 Jamks P. C. Southall. Pp. xxiii, 626, with 169 figures. New 

 York, 1910 (The Macmillan Company). — This is a notable book 

 which surpasses all others in the English language treating of the 

 same subjects. The very great number of propositions in geo- 

 metrical optics are presented clearly, in a carefully studied 

 notation, which is, except in a few cases where other consider- 

 ations are of greater weight, consistent and lucid. The diagrams 

 are sufficient in number and very clear, with the too rare quality 

 of good taste in respect to all the details which determine the 

 character of such illustrations. Most excellent features of the 

 book are its bibliography and historical notes, which are very 

 complete. The only striking omission observed is that of the 

 admirably convenient — perhaps the most convenient of all— col- 

 lection of formulas for rigid computation of the constants of a 

 system of centered lenses by P. A. Hansen. These features 

 make the volume invaluable to one who seeks a knowledge of 

 what has been accomplished in this field during the three cen- 

 turies in which the problems of geometrical optics have been 

 continuously increasing in importance. 



When we come, however, to consider the utility of the methods 

 and equations deduced in the text to the designer of optical 

 apparatus, we must give more restricted praise, since they empha- 

 size what is relatively unimportant in practice and thrust more or 

 less into the background those features which are essential. 

 Excellent examples in support of this assertion are afforded by 

 the only numerical calculations in the book, namely, the calcula- 



