CONTENTvS 



Originai, Papers Page 



General Science. — A list of one hundred popular books in science. Compiled by a 



Committee of the Academy 353 



Physics. — The wave lengths of X-rays. Ralph W. G. Wyckoff 366 



Abstracts 



Optics 374 



Geodesy 374 



Inorganic Chemistry 374 



Geology •. 375 



Ceramics 377 



Proceedings 



Anthropological Society 377 



Scientific Notes and News 370 



ANNOUNCEMENTS OF MEETINGS OE THE ACADEMY AND 



AFFILIATED SOCIETIES 



Tuesday, October 4. The Botanical Society, at the Cosmos Club at 8 p. m. 

 Program : 



W. A. Orton : The Dahlia: group classification, climatic requirements, and aims of breeders. 

 J. B. S. Norton: The Dahlia: varieties and history. 

 W. E. Safford: The Dahlia: botany and chemistry. 



Thursday, October fi. The Entomological Society. 



OFFICERS OF THE ACADEMY 



President: Alfred H. Brooks, Geological Survey. 

 Corresponding Secretary: Robert B. Sosman, Geophysical Laboratory. 

 Recording Secretary: William R. Maxon, National Museum. 

 Treasurer: R. L. Faris, Coast and Geodetic Survey. 



