492 Notices respecting New Boohs. 



The proofs and explanations given are not always remarkable 

 for elegance of treatment. Thus, in dealing with the formula for 

 the E.M.E. of a dynamo, p. 61, the author establishes it by sup- 

 posing that the E.M.E. in each conductor follows the sine law, and 

 then calculates the mean value of the E.M.E. ! This ponderous 

 and clumsy treatment is not only unnecessary, but is positively 

 misleading ; for there is no dynamo in existence in whose conduc- 

 tors the E.M.E.- wave so much as approaches the sine law. 



As a book of reference, the work should prove useful, for it 

 contains a large number of important data. In the section 

 dealing with inductance, in particular, we notice some very useful 

 approximate formulae for the self-inductances of coils. 



Cryoscopie. Par E. M. Eaoult. Paris: C. INaud. 1901. Pp. xiii 

 -f- 106. (Scientia Series, No. 13.) 



The work of the late E. M. Eaoult is of such far-reaching im- 

 portance that his name is one of the most familiar to students of 

 physical chemistry. Happily for such students, he was enabled, 

 almost immediately before his death, to give the clear and 

 fascinating account of his important researches in the monograph 

 before us. We could wish for no better exposition of the subject. 

 After an account of some general principles in Part I. we are in 

 Part II. introduced to the experimental methods of cryoscopy. 

 Part III. deals with the cryoscopy of organic compounds, and 

 Part IV. with that of electrolytes — a subject which, in the early 

 days of the science, was beset with so man y serious difficulties that 

 Eaoult's work was accepted with very considerable reserve, if not 

 diffidence, until the daring and brilliant speculations of Arrhenius 

 restored the confidence of the scientific public in the soundness of 

 Eaoult's generalizations. 



The volume is embellished with a portrait of the author, and an 

 appreciative sketch of his career and work by his friend and pupil, 

 M. E. Lespieau. 



Bericht ilber die Internationale Experten-Conferenz fur Weiter- 

 schiessen in Graz (XXXIX. Band cler Jahrbiicher der K. K. 

 Central- An stalt t'iir Meteorolocjie und Erdmagnetismus). Wien : 

 Wilhelm Braumiiller. 1902. " Pp. iv+154. 



Anyone interested in either meteorology or folklore will find the 

 present volume interesting reading. Edited by J. M. Pernter, it 

 contains a number of valuable contributions from experts on the 

 various aspects of the modern system of battling with hail-storms, 

 which originated in Graz, and is now extensively practised both 

 there and in Italy. As to whether a hail-storm can or cannot be 

 averted by the firing of specially-constructed cannon is a question 

 still sub judice. But it is interesting to learn, from the opening 

 paper of this Heport, that the belief in the efficacy of such a 

 method is of comparatively great antiquity. 



