31:0 



SCIENCE. 



[N.S. Vol. XXI. No. 531. 



of 1 -f- )\ : 1 -f J'o, where )\ and are the 

 reflection coefficients of the two surfaces. 



The Distribution of Energy in the Visible 

 Spectrum. Edward L. Nichols, Cor- 

 nell University. (To be published in the 

 I'hysical Review.) 



'This paper gives definite numerical and 

 graphical data for the variation of in- 

 tensity with wave-length in the visible 

 spectrum of various sources of light such 

 ;as the Hefner lamp, the ordinary gas flame, 

 the petroleum flame, the acetylene flame, 

 the Nernst filament, the lime light, the 

 magnesium light and the carbon arc light; 

 also in the spectrum of incandescent bodies 

 such as carbon, platinum and zinc oxide at 

 known temperatures. 



Hitherto our knowledge of these spectra 

 has been relative, each being compared with 

 some other taken as a reference standard. 

 It is now possible, however, to reduce all 

 •spectrophotometric comparisons to absolute 

 ^measure. 



A Note on Interference ivith the Bi-Prism. 

 Wm. McClei.lan, University of Penn- 

 sylvania. 



The condition that diffraction and inter- 

 ference lines obtained by means of the bi- 

 prism shall be seen separately, depends on 

 the relative positions of the screen prism 

 and slit, and the angle of the prism. The 

 writer has taken several photographs to 

 illustrate the various fields which may be 

 obtained from the same prism. 



The Evolution of Hydrogen from the 

 fCathode in Gases and its Association ivith 

 'Cathode Kays. Clarence A. Skinner, 

 University of Nebraska. 



JExhibil of Liquid Air Machine in Opera- 

 tion. Arthur W. Goodspeed, Univer- 

 sity of Pennsylvania. 



Dayton C. Miller, 

 Secretary of Section B. 



THE CONVENTION OF THE ASSOCIATION OF 

 AMERICAN AGIilCVLTURAL COLLEGES 

 AND EXPERIMENT STATIONS. 



TlJE eighteenth annual convention of 

 this association was held in the Chamberlain 

 Hotel, at Des Moines, Iowa, November 1-3. 

 It was the first meeting under the new con- 

 stitution, which reduces the number of sec- 

 tions from five to two : and the advantage 

 of the new plan was very marked in en- 

 abling delegates to follow the discussions 

 more closely, and in concentrating the delib- 

 erations upon questions of administration 

 and methods of work. The two sections 

 under the present constitution are (1) on 

 college work and administration, and (2) 

 experiment station work. 



The general sessions were presided over 

 by Dr. W. 0. Thompson, of the University 

 of Ohio, who delivered the customary presi- 

 dential address. This dealt with 'Some 

 Problems in the Colleges of Agriculture 

 and Mechanic Arts,' and gave special 

 attention to the agricultural phase of their 

 work. Among the problems noted were the 

 conditions in the agricultural communities, 

 the much-discussed tendency away from the 

 farm, and the frequent lack of opportunity 

 on the part of the farmer's boy for indi- 

 vidual initiative. It was urged that farm 

 life must not be the refuge of necessity, 

 that not all farmers' sons are suited to be 

 farmers any more than all lawyers' sons 

 are suited to that profession, and that 

 marked changes in farming have taken 

 place in recent years which call for special 

 aptitude and training quite as much as any 

 other work in life. It was pointed out that 

 intelligent operation of the farm is now 

 necessary for any margin of profit, and the 

 fallacy that unintelligent men can make 

 successful farmers or satisfactory farm 

 laborers was denounced. 'We need to 

 know that intelligence on the farm will 

 produce results just as surelj" as elsewhere,' 



