The Science Series 



Edited by EDWARD LEE THORNDIKE, Ph.D., Columbia Uni 

 versity, with the cooperation of FRANK. EVERS BEDDARD, 

 F.R.S., in Great Britain. 



Each volume of the series treats of some department of 

 science with reference to the most recent advances, and 

 is contributed by an author of acknowledged authority. 

 Every effort is made to maintain the standard set by the 

 first volumes, until the series shall represent the more im- 

 portant aspects of contemporary science. The advance of 

 science has been so rapid, and its place in modern life has 

 become so dominant, that it is needful to revise continually 

 the statement of its results, and to put these in a form that is 

 intelligible and attractive. The man of science can himself 

 be a specialist in one department only, yet it is necessary for 

 him to keep abreast of scientific progress in many directions. 

 The results of modern science are of use in nearly every pro- 

 fession and calling, and are an essential part of modern 

 education and culture. A series of scientific books, such as 

 has been planned, should be assured of a wide circulation, 

 and should contribute greatly to the advance and diffusion ot 

 scientific knowledge. 



The volumes are issued in octavo form, and are fully illus- 

 trated in so far as the subject-matter calls for illustrations. 



G. P. PUTNAM'S SONS, NEW YORK & LONDON 



