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 



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Entered as second-class matter January 21, 1922, at the Post 

 Office at Utica, N. Y., under the Act of March 3, 1879. 



Vol. LV Febeuaby 17, 1922 No. 1416 



The Spectroscopy of the Extreme Ultra- 

 violet: PRorESSOR Theodore Lyman 161 



American Association for the Advancement 

 of Science: 

 Report of the Committee on an Interna- 

 tional Auxiliary Language: Dr. S. W. 

 Stratton 166 



The Psychological Corporation 169 



Scientific Events: 



List of Scientific periodicals ; The Gorgas 

 Memorial Institute; The Beorganization of 

 Mathematics in Secondary Education; The 

 British Columbia Expedition of the Uni- 

 versity of California; Bache Fund of the 

 National Academy of Sciences 171 



Scientific Notes and News 173 



University and Educational Notes 177 



Discussion and Correspondence: 



Kentucky and the Theory of Evolution: 

 Professor Arthur M. Miller. Selativity 

 and Star Diameters: Dr.' Reginald A. 

 Pessenden. The Etiology of Tipburn: 

 Dr. John E. Eter 178 



Quotations : 



Economy in Publication 181 



Scientific BooTcs: 



Fernald's Applied Entomology: Profes- 

 sor Glenn W. Herrick 182 



Special Articles: 



High Speed High Vacua Mercury Vapor 

 Pumps: Professor Chas. T. Knipp. ' The 

 Neuromotor Apparatus of Paramecium: 

 Dr. Charles "W. Rees 183 



The American Chemical Society: Dr. Charles 

 Xi. Parsons 185 



THE SPECTROSCOPY OF THE EX- 

 TREME ULTRA-VIOLETi 



In the year 1914 I published a monogi-aph 

 under the title of "The Spectroscopy of the 

 Extreme Ultra- Violet" ; to-day 1 wish to trace 

 the progress of the subject to the present time. 

 The part of the spectrum with which we are 

 concerned has for its less refrangible limit 

 wave-length 2,000 A.U. ; it now extends to a 

 region separated from X-rays by less than 

 200 units. 



It is more than thii-ty years ago since Victor 

 Schumann led the way into this undiscovered 

 country, and gave his name to the region he 

 explored. His methods and his results are 

 familiar to all spectroscopists, but it may be 

 well to remind you of the nature of the difB- 

 culties which he conquered. The extension of 

 the spectrmn in the ultra-violet is opposed by 

 three factors, the opacity of the materials 

 usually employed in the making of prisms and 

 lenses, the opacity of gelatine, and the opacity 

 of the air. By the use of fluorite, by the inven- 

 tion of a special photographic emulsion and by 

 placing his spectrograph in vacuum, Schumann 

 demonstrated that the spectrum could be 

 extended bj' nearh' eight hundred units. 



The result, though easily described, was only 

 reached after years of patient toil, for experi- 

 mentation in this region was, and still is, beset 

 with great difficulties. Every contribution 

 which Schumann made to the subject is marked 

 by the greatest exactness and finish; his field 

 was limited, but within that field not only his 

 technique but also his reasoning remain a 

 model to this day. 



The first and most characteristic jDroduct of 

 his labors was a series of exquisite spectro- 

 grams of hydrogen; but owing to the lack of 

 a dispersion curve for fluorite, it was out of 

 the question to attach wavelengths to the lines 



1 Address of the president of the American 

 Physical Society, Toronto, December, 1921. 



