SCIENCE- ADVERTISEMENTS 



The Fahy Experimental Permeameter 



JAMES G. 



To meet the need of a conveniently 

 arranged permeameter for making 

 magnetic measurements in laiorci- 

 tory practice, Mr. Frank P. Fahy 

 (Consulting Magnetic Engineer) has 

 designed an outfit that we recom- 

 mend to Professors of Physics and 

 Engineering. It comprises a Mag- 

 netizing Solenoid and Control Box; 

 and in addition there should be 

 available a galvanometer, adjustable 

 resistances and storage battery — all 

 of which we are ready to supply. 



Write for Bulletin 990 

 1211-13 Arch St., Philadelphia 



Third Edition 



AMERICAN MEN OF SCIENCE 



A BIOGRAPHICAL DIRECTORY 



EDITED BY J. McKEEN CATTELL AND DEAN R. BRIMHALL 



The third edition of the Directory contains about 9,600 sketches as compared with 

 4,000 in the first edition and 5,500 in the second edition. The work should be in the 

 hands of all those who are directly or indirectly interested in scientific work. 



( 1 ) Men of science will find it indispensable. It gives not only the names, ad- 

 dresses, scientific records and the like of their fellow workers, but also an invaluable 

 summary of the research work of the country, completed and in progress. 



(2) Those interested in science, even though they may not be professionally en- 

 gaged in research work, will find much of interest and value to them in the book. 



(3) Executives in institutions of learning and others brought into relations with 

 scientific men will use the book constantly. 



(4) Editors of newspapers and periodicals will find it to be one of the works of 

 reference that they will need most frequently. 



(5) Ijbiaries will find the book to be a necessary addition to their reference 

 shelves. 



Price, Ten Dollars, Net, Postage Paid 



THE SCIENCE PRESS 



Grand Central Terminal, New York, N. Y. 



