Sot ices respecting Sew Books. 387 



himself unable personally to undertake the task of revision, and 

 this was entrusted to Dr. Eppenstein, with the co-operation of 

 M. von Kohr. The new edition fully maintains the reputation of 

 its predecessor, and is sure to find an honoured place on the 

 shelves of every physical library. 



One of the most important features of the work is the extreme 

 generality of the theory of image formation as developed by Abbe. 

 It is interesting to point out the fact, mentioned in the present 

 edition, that the germs of this theory are contained in a neglected 

 paper of Clerk Maxwell's. " On the General Laws of Optical 

 Instruments," contributed to the Philosophical Magazine in 1856. 



It will be convenient to present in brief outline the contents of 

 the present volume. The introductory section deals with the laws 

 of geometrical optics. This is followed by Abbe's geometrical 

 theory of image formation. Then comes a section dealing with the 

 formation of optical images by means of thin axial and oblique 

 pencils. Spherical and chromatic aberrations are next considered. 

 The formation of images by means of prisms and prism systems, 

 and the conditions of achromatism, are then dealt with. The 

 next few sections are devoted to the important subjects of apertures 

 and the effects depending on them, the optical system of the eye 

 and vision. This latter subject is dealt with by M. von Rohr, who 

 also contributes the two succeeding sections on the photographic 

 objective and spectacles. The sections on the magnifying- glass 

 and the compound microscope are due to Czapski, and are followed 

 by two sections on projection systems and methods of illumination, 

 contributed by Eppenstein. The telescope receives very careful 

 treatment at the hands of Czapski, to whom is also due the 

 excellent concluding section on the methods of determining 

 experimentally the constants of optical instruments. 



The book forms a veritable mine of information on many 

 important points either not dealt with at all or else very perfunc- 

 torily in the ordinary type of text-book, and it contains numerous 

 references to the literature of the subject. The publishers are to 

 be congratulated on the clearness of the type and excellence of 

 the illustrations. 



La Staiiquc Chimir^ue. Baste sur les deux Principles Fondamentaux 



de la Thermodynamique. Par le Lieutenant-Colonel E. Aries. 

 Paris: A.Hermann. 1904. Pp. viii + 251. 



Tins work is intended as an introduction to the methods of modern 

 theoretical chemistry, in which thermodynamical principles play so 

 important a part. The author deals only with reversible operations, 

 and confines his attention to those cases in which temperature and 

 pressure are the two independent variables. The wisdom of the 

 restrictions which the author thus voluntarily imposes on himself 

 is fully apparent in the extreme lucidity of treatment which 

 characterises the book. And by the thorough discussion of a 

 number of comparatively simple concrete cases, the. reader is enabled 

 to gain an in&ight into the princples of the science which a more 



