June 2, 1911] 



SCIENCE 



857 



Professor Southall, in his book on geo- 

 metrical optics, undertook to put in one vol- 

 ume most of that which is valuable on the 

 subject, especially as applied to optical in- 

 struments. He was filled with enthusiasm, 

 inspired by a sincere belief in the value of the 

 subject and an ambition to supply the ad- 

 mitted deficiency in the English language. 



Partly with the object of supplying this defi- 

 ciency, and partly also in the hope (if I may 

 venture to express it) of rekindling among Eng- 

 lish-speaking nations interest in a study not only 

 abundantly worthy for its own sake and unde- 

 servedly neglected, but still capable, under good 

 cultivation, of yielding results of far-reaching 

 importance in nearly every field of scientific re- 

 search, I have prepared the following work. . . . 



It is such enthusiasm as this that holds one 

 to the severe labor of preparing a large book 

 and of making it a good book. While it is 

 doubtful whether any large number of scien- 

 tific men will follow Professor Southall in his 

 very high estimate regarding the relative 

 value of geometrical optics and in his optim- 

 ism respecting its future, the careful and ex- 

 haustive book which he has prepared will un- 

 doubtedly do much to bring the geometrical 

 theory of optical instruments into greater 

 favor in this country. 



Professor Southall treats in successive 

 chapters the fundamental properties of geo- 

 metrical optics, the properties of rays of light, 

 reflection and refraction at a plane surface, 

 refraction through prisms, reflection and re- 

 fraction of paraxial rays at a spherical sur- 

 face, refraction of paraxial rays through thin 

 lenses, the theory of optical imagery, lenses 

 and lens systems, exact trigonometrical 

 formuke for tracing rays through spherical 

 surfaces and centered systems of spherical 

 surfaces, theory of an infinitely narrow 

 bundle through an optical system, theory of 

 spherical aberrations including Seidel's theory 

 developed to aberrations of the third order, 

 color-phenomena and chromatic aberrations, 

 aperture, and field of view and brightness of 

 images. It is seen from this how extensive is 

 the subject-matter treated. In general, all 

 the chief discussions of the more important 



topics have been given. This has led to a 

 duplication in very many instances; particu- 

 larly, many subjects are treated both geo- 

 metrically and analytically. This, of course, 

 is not to be regarded as a positive fault in an 

 exhaustive treatise, for the one method will 

 appeal to some and the other method to others. 

 But probably many will wish, on reading the 

 book, that especially the first part had been 

 written more concisely and with fewer repeti- 

 tions of subject-matter under different forms. 

 This would not be, however, in harmony with 

 the obvious plan of reproducing essentially all 

 that is of value in the subject. The alternate 

 plan is to adopt a definite point of view and to 

 develop the subject systematically from that 

 point of view. 



Probably the greatest service rendered by 

 Professor Southall has been in setting forth 

 clearly and consecutively the splendid optical 

 theories of the German writers of the last 

 half century, particularly those of Seidel 

 and Abbe. His book may inspire us to divide 

 with the Germans the future developments in 

 these lines. At any rate all who have an in- 

 terest in the subject will thank him that he 

 has so well done his part, for it will not be 

 questioned that he has prepared the best and 

 most exhaustive work on geometrical optics in 

 the English language. So far as the question 

 of completeness is concerned there seems room 

 for regret, and that mostly on the part of prac- 

 tical opticians, only in that the theories are 

 not illustrated more by numerical examples 

 based on the glasses of commerce. 



F. E. MOULTON 



A Laboratory Manual of Inorganic Chemistry. 

 By Eugene C. Bingham, Ph.D. (Johns Hop- 

 kins), Professor of Chemistry, Richmond 

 College, Richmond, Va., and George F. 

 White, Ph.D. (Johns Hopkins), Associate 

 Professor of Chemistry, Richmond College, 

 Richmond, Va. New York, John Wiley & 

 Sons ; London, Chapman and Hall, Limited. 

 1911. 12mo, pp. viiirfl47. Cloth, $1.00 

 net (4s. 6d. net). 

 In the preface the authors state that, in 



their opinion, " a course in inorganic prepara- 



