172 SCIENCE PROGRESS 



The Year-Book of the Scientific and Learned Societies of Great Britain and 

 Ireland. A record of the work done in Science, Literature, and Art during the 

 Session 1916-17, by numerous Societies and Government Institutions. 

 Compiled from Official Sources. Thirty-fourth Annual Issue. London : 

 Charles Griffin & Co., Exeter Street, Strand, W.C.2. (Pp. viii + 334.) 

 Price gs. net. 



The Athenaeum Subject-Index to Periodicals, 1916. Science and Technology, 

 including Hygiene and Sport. Issued at the Request of the Council of the 

 Library Association. London : The Athenaeum, Bream's Buildings, Chancery 

 Lane, E.C.4 ; New York : Messrs. B. F. Stevens & Brown, 16, Beaver Street. 

 (Pp. 162.) Price 10s. net. 



ERRATUM 



In the January number of Science Progress the denominator 

 of the formula on p. 507 should read : 



instead of 



Printed by Hazell, Watson & Viney, Ld., London and Aylssbury, England. 



