SCIENCE 



Friday, Apeil 6, 1917 



CONTENTS 

 Badiation and Atomic Structure: Professor 

 Egbert -§■; Millikan 421 



George Christian Hoffmann: Dr. H. M. Ami. 430 



Scientific Events: — 

 Lectures on Samitary Science at Rutgers 

 College; Scientific Besearch and the Elec- 

 trical World; A Census of Chemists 430 



Scientific Notes and News 332 



University and Educational News 334 



Discussion and Correspondence: — 



Epicene Profiles in Desert Lands: Dr. 

 Charles Ketes. The Food Supply of Some 

 Water Bugs: Dr. H. B. Htjngerford. The 

 Doctrine of Evolution and the Church: Dr. 

 Marcus Benjamin. The Manufacture of 

 Apparatus and Chemicals: Professor Louis 

 Baumann. Lord Lister on the Value of 

 Vivisection: Dr. W. W. Keen 335 



Quotations: — 



The American Association and WorTc in 

 Agriculture 338 



Scientific EooTcs: — 



Clements on Plant Succession: Professor 

 Raymond J. Pool 339 



Special Articles: — 



Tractive Besistances to Motor Trucks on 

 Boads and Pavements: Professor A. E. 

 Kbnnellt and O. R. Schurig 341 



Societies and Academies: — 



The Biological Society of Washington : Dr. 

 M. W. Lyon, Jr 343 



MSS. intended for publication and books, etc., intended for 

 review should be sent to Professor J. McKeen Cattell, Garrison- 

 on-Hudson, N. Y. 



RADIATION AND ATOMIC STRUCTUREi 



While the study of the physical and 

 chemical properties of matter has produced 

 our present atomic theory and furnished 

 most of the information which is available 

 about the way in which the myriad molec- 

 ular structures are built up out of their 

 atomic constituents, it has been chiefly the 

 facts of radiation which have provided 

 reliable information about the inner struc- 

 ture of the atom itself. Indeed, during all 

 the years in which the dogma of the inde- 

 structible and indivisible atom was upon 

 the stage, it was the complexity of the 

 spectra even of simple gases which kept 

 the physicist in the path of truth and 

 caused him continually to insist that the 

 atom could not be an ultimate thing, but 

 rather that it must have a structure, and a 

 very intricate one at that — as intricate, in 

 Rowland's phrase, as a grand piano. 



Yet the evidence of spectroscopy, though 

 tremendously suggestive in the series rela- 

 tionships brought to light between the fre- 

 quencies of the different lines of a given 

 substance, was, after all, most disappoint- 

 ing, in that it remained wholly uninter- 

 preted in terms of any mechanical model. 

 No vibrating system was known which 

 could produce frequencies related in the 

 manner corresponding to the frequencies 

 found even in the simplest of series, viz., 

 the Balmer series of hydrogen. The dis- 

 covery and study in the late nineties of 

 corpuscular radiations of the alpha and 

 beta type, with the changes in chemical 

 properties accompanying them, merely 



1 Address of the president of the American 

 Physical Society, New York, December, 1916. 



