SCIENCE 



Friday, Decembbe 4, 1914 



CONTENTS 



X-rays and Crystalline Structure: Pbofessok 

 William H. Bragg 795 



Walter SolbrooTc GasTcell: De. F. H. Garkison. 802 



Gashell's WorTc on Organic Evolution: Pko- 

 FESSOK F. H. Pike 805 



The Philadelphia Meeting of the American 

 Association for the Advancement of Sci- 

 ence : Dr. L. 0. Howard 807 



The Convocation WeeTc Meeting of Scientific 

 Societies 808 



Soientifio Notes and News 810 



University and Educational News 813 



Discussion and Correspondence : — 



Minute Animal Parasites: H. B. Fantham, 

 A. Porter, Professor Gaby N. Calkins. 

 A Filefish new to the Atlantic Coast of the 

 United States : Dr. Hugh M. Smith 814 



Scientific BooTcs:-— 



Chamberlin and Salisbury's Introductory 

 Geology: Professor H. L. Fairchild. 

 Maurer's Technical Mechanics: Professor 

 L. M. HosKiNs. Smith 's Principles of Elec- 

 trical Measurements: Professor Frederick 

 Bedell. Bead's Bacteriology: Professor 

 H. W. Conn. Major's Elements of Psy- 

 chology : Professor. E. S. Woodworth .... 816 



Scientific Journals and Articles 821 



Notes on Meteorology: Charles F. Brooks. 822 

 Special Articles: — 



Some Physical Properties of the Cell Nu- 

 cleus: Professor Eobert Chambers, Jr. 

 The Geologic Bistory of EaTce Lahontan: 

 Dr. J. Claude Jones 824 



Societies and Academies: — • 



The American Mathematical Society: Pro- 

 fessor F. N. Cole. The American Philo- 

 sophical Society. The New Orleans Acad- 

 emy of Sciences: Professor R. S. Cocks. 

 The Anthropological Society of Washing- 

 ton : Dr. Daniel Folkmar 831 



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

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

 on-Hudson, N. Y. 



X-SA¥8 AND CBTSTALLINE STBUCTUBE^ 

 Two years have gone by since Dr. Laue 

 made his surprising discovery of the inter- 

 ference effects accompanying the passage of 

 X-rays through crystals. The pioneer experi- 

 ment has opened the way for many others, and 

 a very large amount of work, theoretical and 

 practical, has now been done. As the prelim- 

 inary exploration of the new country has pro- 

 ceeded, our first estimate of its resources has 

 grown continuously; we have learned many 

 things which help us to a better understand- 

 ing of phenomena already familiar, and we 

 have seen avenues of enquiry open out before 

 us which as yet there has been little time to 

 follow. The work is full of opportunities for 

 exact quantitative measurements, where pre- 

 cision is sure to bring its due reward. There 

 is enough work in sight to absorb the energies 

 of many experimenters, and there is sure to be 

 far more than we can see. When we consider 

 the wideness of the new field, the quality and 

 quantity of the work to be done in it, and the 

 importance of the issues, we are scarcely guilty 

 of over-statement if we say that Laue's experi- 

 ment has led to the development of a new 

 science. 



The experiment itself — to put it very briefly 

 — constitutes a proof that X-rays consist of 

 extremely short ether waves. In order to ap- 

 preciate the value of this demonstration, we 

 must bear in mind the present conditions of 

 our knowledge of the laws of radiation in 

 general. Let us consider very shortly how the 

 whole matter stood when the new work was 

 begun. 



When X-rays were first discovered eighteen 

 years ago it was soon pointed out that they 

 might consist of electro-magnetic disturbance 

 of the ether analogous to those supposed to 



1 Read before the weekly evening meeting of 

 the Royal Institution of Great Britain, June 5, 

 1914. ' 



AV. 



