Notices respecting New Books. 



379 



current), by which it was possible to complete the circuit of 

 the galvanometer for the parts of the current AB or BC,"and 

 BC or CD, and thus to compare immediately p x with p 2 , and 

 p 2 with p z . 



In the first part of my investigation I measured without 

 field the resistance of a bismuth spiral with a telephone, and 



Fig. a 



Fig. 2. 



Is 



an alternating 



current obtained from a Kohlrausch induc- 

 torium. As interrupter I took a toothed wheel turned by an 

 electromotor; the frequency of interruption varied between 92 

 and 2088, the difference of resistance varied with the frequency 

 between 0*12 and 0*27 per cent. 



March 18, 1805. 



XXXVIII. Notices respecting New Books. 



The Great Ice Age and its Relation to the Antiquity of Man. By 

 James Geikie, D.C.L., LL.D., F.R.S., $c. Third Edition. 

 Pages i-xxviii ; and 1-450 ; with 18 maps and 78 illustrations. 

 8vo. Stanford: London, 1894. 



THIS new edition of an important geological work has been 

 " largely rewritten " by the Author, and contains two new 

 chapters on' the " Glacial Phenomena of North America/'* by 

 Professor T. C. Chamberlin. 



As a systematic account of the visible results of ice-action on a 

 large scale in this part of the World, and of the probable history 

 of the origin, progress, aud end of this period of glaciation, we 

 have here a valuable repertory of facts and opinions recorded by 

 many geological enquirers and grouped by one who has studied 

 the subject for almost a life-time. Formerly one of the members 

 of the Geological Survey engaged in mapping the geology of 

 Scotland, and now holding the Chair of Geology at Edinburgh, 

 Professor James Geikie has naturally taken up one of the most 

 interesting groups of geological features in that country as a 



