A Weekly Journal devoted to the Advancement 

 of Science, publishing the official notices and 

 proceedings of the American Association for the 

 Advancement of Science, edited by J. McKeen 

 Cattell and published every Friday by 



THE SCIENCE PRESS 



! I Liberty St., Utica, N. Y. Garrison, N. Y, 



Nevr York City: Grand Central Terminal 



Single Copies, 15 Cts. Annual Subscription, S6.00 



Entered as seeond-cla, 

 )ffico at Utica. N. Y.. i 



matter January 21. 1922, at the Post 

 der the Act o£ Marcli 3, 1879. 



March 3, 1922 



Ihe American Association for the Advance- 

 ment of Science: 

 Atomic Nuclei: PRorESSOR J. C. McLen- 

 nan 219 



Pt'ogress in Metric Standardization: Dk. 

 Eugene C. Bingh.oi 232 



The Banding of Birds: Charles L. Whittle 233 



Scientific Events: 



Conference on Business Training of the 

 Engineer and Engineering Training for 

 Students of Business; Gift of the BocTce- 

 feller Foundation for a School of Hygiene 

 in London; Lectures on Chemical Engi- 

 neering; The Sheldon Memorial; The 

 Bamsay Memorial Fellowship 234 



Scientific Notes and News 237 



TJniversity and Educational Notes 240 



Discussion and Correspondence: 



Duty on English Books: Professor G. D. 

 Habris. Alternate Bearing of Fruit Trees: 

 Dr. Harold B. Tuket. The Writing of 

 Popular Science: Dr. Edwin E. Slosson.... 240 



Quotations : 



William Jennings Bryan on Evolution 242 



Scientific Books: 



Clarke on James Hall of Albany: Pro- 

 fessor Charles Schuchert 243 



Special Articles: 



The Synthesis of Full Coloration in Phlox: 

 Dr. J. P. Kellt 245 



The Proposed Federation of Biological Socie- 

 ties: Professor A. Franklin Skull 24.) 



ATOMIC NUCLEU 



I. INTRODUCTION 



The conception that atoms consisted of cen- 

 tral positively charged nuclei of small dimen- 

 sions surrounded by one or more systems of 

 electrons whose aggregate charge of negative 

 electricity exactly neutralized the nuclear posi- 

 tive charge, arose in an attempt by Rutherford^ 

 to explain the large angle scattering of a rays 

 obtained when these traversed thin foils or 

 sheets of various metals. 



To account for the results obtained it was 

 found necessary to assume that the positively 

 charged nucleus contained nearly all the mass 

 of an atom and that the dimensions of the 

 nucleus were very small compared with the 

 ordinarily accepted magnitude of the diameter 

 of the atom. 



On this view the electric field close to the 

 nucleus was very intense and therefore sufii- 

 eient to deflect a particles which in traversing 

 sheets of metal happened to pass close to 

 nuclei. 



Assuming the electric field of nuclei to be 

 central and to follow the inverse square law, 

 Rutherford showed that an a particle pro- 

 jected so as to pass close to the nucleus of aii 

 atom would describe a hyperbolic orbit about 

 the nucleus and that the magnitude of the 

 deflection impressed upon it was determined 

 by the closeness of its approach to the nucleus. 



(a) The electric charge on nuclei. 



On this theory Rutherford showed by deduc- 

 tions made from observations on the single 

 encounter large angle scattering of a rays that 

 the resultant charge on the nucleus was about 

 V2 A e where A is the atomic weight of the 



1 Address of the vice-president and chairman of 

 Section B — Physics, the American Association 

 for the Advancement of Science, Toronto, De- 

 cember 29, 1921. 



2 Eutlierf ord, Phil. Mag., Vol. 21, p. 669, 1911; 

 Phil. Mag., Vol. 27, p. 448, 1914. 



