The Popular Science Monthly 



Entered in the Post Office in Lancaster, Pa., as second-class matter 



CONTENTS OF MAY NUMBER 



The Electronic Theory of Electricity. Profkssor 

 J. A. Fleming. 



Sulfuric Acid and its Manufacture by the Contact 

 process. Dr. R. Kxeitsch. 



The Physical Basis of Heredity. Professor Carl 



H. ElGENMANN. 



Children's Vocabularies. M. C. and H. Gale. 



Mescal : A Study of a Divine Plant. Havelock 

 Ellts. 



Infectious Diseases. Dr. Alfred Springer. 



The Relation ot Electrically charged Molecules 

 to Physiological Processes. Professor Jacques 

 Loeb. 



An Afternoon at Chelles and the Earliest Evi- 

 dence of Human Industry in France. Pro- 

 fessor A. S. Packard. 



The Progress of Science : 



The Will of Cecil Rhodes; The American 

 University ; The American Philosophical 

 Society and the American Philosophical Asso- 

 ciation ; Societies for the Scientific Study of 

 Education; Biographies of Eminent Chemists; 

 The Conditions of Chemical Action; The 

 Periodicity of Solar Phenomena; The Com- 

 parative Growth of Bacteria in Milk ; Scien- 

 tific Items. 



CONTENTS OF JUNE NUMBER 



Lord Kelvin. Frontispiece. 



On the Definition of Some Modern Sciences: 

 Introduction. Professor W. H. Dall. 

 Statistics. Hon. Carroll D. "Wright. 

 Political Economy. Professor Roland P. 



Falkneu. 

 Psychology. Professor E. A. Pace. 

 Sociology. Lester F. Ward. 



The CommercialValue of Human Life. Marshall 

 0. Leighton. 



Instinct. Douglas A. Spalding. 



Educational Value of Photomicrography. Arthur 

 Curtis Scott. 



Sugar and the Sugar Beet. Dr. John Waddell. 



Peter Guthrie Tait. C. K. Edmunds. 



Concerning the American University. Professor 

 J. McKeen Cattell. 



Scientific Literature: 

 Botany. 



The Progress of Science : 



Lord Kelvin in America; The National Acad- 

 emy of Sciences ; The Metric System in the 

 United States; The Causes of Volcanic 

 Eruptions ; Some Facts and Figures concern- 

 ing the Earth ; Biographies of Eminent 

 Chemists ; The Origin of the Human Species ; 

 Scientific Items. 



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