CONTENTS 



y 



Original Papers 



Page 



Mathematics and Bacteriology. — On the dilution method of counting bacteria. P. V. 



Wells and W. F. Wells 265 



Physics. — Soft characteristic X-rays from arcs in gases and vapors. F. L. MohlER and 



Paul D. Foote 273 



Terrestrial Magnetism. — The bearing of the Earth's size upon changes in its magneti- 

 zation. W. F. G. SwANN 275 



Petrology. — Preliminary note on monticellite alnoite from Isle Cadieux, Quebec. 

 N. L. BowEN 278 



Abstracts .; 



Physics ' 281 ; 



Geology 282 



Zoology 283 



Proceedings 



Philosophical Society 283 



ScxENTiFxc Notes and News 287 ; 



OFFICERS OF THE ACADEMY 



President: Alfred H. Brooks, Geological Survey. 

 Corresponding Secretary: Robert B. Sosman, Geophysical Laboratory. 

 Recording Secretary: Wii^uam R. Maxon, National Museum. 

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



NOTE 



The May, June and July numbers of the Journal have been delayed on account of 

 strikes in the printing trades. 



ANNOUNCEMENTS OF MEETINGS OF THE ACADEMY AND 



AFFILIATED SOCIETIES 



PROGRAMS ANNOUNCED SINCE THE PRECEDING ISSUE 



OF THE JOURNAL^ 



Monday, June 27. The Botanical Society, at the Cosmos Club, at 8 p.m. Program: J. 

 F. Rock: A trip through North Siam, Burma, and Assam for the Office of Foreign 

 Seed and Plant Introduction. 



Received too late for publication before the date of the meeting. 



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