JAIJTJART 1, 1915J 



. SCIENCE 



29 



the author, but at the same time it must be 

 said that more attention has been given to the 

 details of certain controversies and experi- 

 ments now largely of historical interest only 

 than might be regarded as required in a book 

 like this. This fondness for detail, how^ever, 

 does not detract seriously from the usefulness 

 of the book to student and practitioner. The 

 references to original sources are very abun- 

 dant and will prove of great help, but they are 

 not given according to any accepted bibliog- 

 raphic standard, the page being omitted in 

 most cases. There are altogether but very few 

 books that attempt to give a comprehensive 

 summary of immunological knowledge of the 

 same general scope as this one by Dr. Zinsser, 

 but their number is increasing; for the pres- 

 ent Dr. Zinsser's is the most serviceable. 



LuDViG Hektoen 



The Norwegian Aurora Polaris Expedition, 

 1902-08. Vol. I. : On the Cause of Magnetic 

 Storms and the Origin of Terrestrial Mag- 

 netism. By Kr. Birkeland. Second Sec- 

 tion. Christiania, H. Aschehoug & Co. 

 1913. 4°. Pp. x + 319-801, with many 

 maps and plates. 



Five years have elapsed since the publica- 

 tion of the first section of the present work, 

 yet, in spite of incessant labor, this second 

 section could not be sooner completed. 

 This was due to the great number and variety 

 of the computations and experiments neces- 

 sary. The author considers that the results 

 attained by the investigation of conditions 

 during positive and negative Polar storms, 

 and particularly the diurnal motion of the 

 respective magnetic storm centers, are so 

 valuable as to fully compensate for the exer- 

 tions and personal sacrifices that the work 

 has cost. 



In order to make it clear whether his con- 

 clusions from widely spread observations in 

 different parts of the world could be harmon- 

 ized with his previous theoretic assumptions, 

 he has carried out a long series of experi- 

 ments with a " terrella " or magnetic globe 

 suspended in a large vacuum-box intended for 

 electrical discharges. He has thus been able 



to obtain photographic representation of the 

 way in which cathode rays move singly, and 

 group themselves in crowds about such a mag- 

 netic globe. Special study has been made of 

 these groups of rays which produce magnetic 

 effects analogous to those observed upon the 

 earth during positive and negative magnetic 

 polar storms. The photographic plates of 

 these experiments are veritably fascinating. 



The author holds that he has demonstrated 

 that the magnetic storms on the earth, polar 

 and equatorial, may be assumed to have as 

 their primary cause the precipitation toward 

 the earth of heliocathode rays, of which the 

 magnetic rigidity is so great that the product 

 H.p for them is usually about 3 X 10" C.G.S. 

 units. He discusses the objections raised to 

 this theory by Schuster and Hale, and states 

 that the experiments which were originally 

 intended to procure analogies capable of ex- 

 plaining terrestrial phenomena, such as the 

 Aurora and "magnetic storms," were after- 

 ward continued to derive information in re- 

 gard to the conditions under which the emis- 

 sion of the assumed heliocathode rays from 

 the sun might be supposed to take place. The 

 terrella was made the cathode in the vacuum 

 chamber and experiments carried on for manj; 

 years. In this research there gradually ap- 

 peared experimental analogies to various 

 cosmic phenomena, such as zodiacal light, 

 Saturn's rings, sun spots and spiral nebulae. 

 Whatever be the fate of the author's hypoth- 

 eses the facts recorded in this work are well 

 worthy the careful study of those interested 

 in electromagnetism. 



W. H. Dall 



Physics of the Household. By Carlton John 

 Lynde, Macdonald College, Canada. 1914. 

 12mo. Cloth. Pp. 313. 

 Professor Lynde's book indicates that the 

 author believes in teaching physics by con- 

 sulting and describing, first, the student's own 

 environment in information, experiences and 

 appliances. These things are the fundamen- 

 tals of this book. The reasons assigned in 

 the preface for the teaching of physics to 

 young students are, " First, that they may ob- 



