SCIENCE 



New Series Friday, August 11, 1922 Annual SnBscniPTioN, $6.00 



Vol. LVI, ]\o. 1441 ' ' Single Copies, 15 Cts. 



DUFF'S 



Edited by A. WiLMER DUFF, Sc.D. 



A College Physics Having as Authors, Specialists 

 in Different Departments 



5th Revised Edition. 609 Illustrations. Cloth, $4.00 



Mechanics and Sound. — By A. Wilmer Duff, Sc.D., Pro- 

 fessor of Physics, Worcester Polytechnic Institute. 



Wave Motion and Light. — By E. Percival Leyyri&j^-Pfe:"^?*^ 

 Professor of Physics, University of Calif^^sH^al'^'' ""' '^^'"/^N 



Heat.— By Charles E. Mendenhall, Ph. |).j^vProfesS8£'<)f "^j 



Physics, University of Wisconsin. V" ' /' 



Electricity and Magnetism. — By Albert P. C^rnM«H''3t-t5., 

 Professor of Physics, University of Illinois. 



Conduction of Electricity through Gases and Radio- Activity. 

 — By R. K. McClung, Sc.D., Assistant Professor of 

 Physics, University of Manitoba. 



More than three-fourths of the schools of engineering in 

 the United States use Duff's Textbook of Physics. The 

 leading schools of Canada, Japan and China also use it. 



P. BLAKBSTON'S SON Sc CO. 



Publishers Philadelphia 



