THE PRINCIPLES OF SCIENCE : 



TREATISE ON LOGIC 



AND 



SCIENTIFIC METHOD. 



W. STANLEY JEVONS, 



LL.D. (EDINB.), M.A. flXD.), F.K.S., 



PROFESSOR OF POLITICAL ECONOMY IN UNIVERSITY COLLEGE, LONDON, 

 EXAMINER IN LOGIC AND MORAL PHILOSOPHY IN THE UNIVERSITY OF LONDON. 



THIRD EDITION. 



JTmtbmt : 



MACMILLAN AND CO. 

 1879. 



Tlie Right of Translation and Reproduction is Reserved. 



