Pbbeuary 25, 1921] 



SCIENCE 



193 



W. A. Hurwitz: "Some properties of methods 

 of evaluation of divergemt sequences." 



W. C. Graustein : ' ' Parallel maps of surfaces. ' ' 



J. H. M. Wedderburn : "On the maximum value 

 of a determinant. ' ' 



J. H. M. Wedderburn: "On the automorphie 

 transformation of a bilinear form." 



J. "W. Lasley, Jr.: "Some special cases of the 

 flecnode transformation of ruled surfaces." 



B. G. D. Richardson: "The theory of relative 

 maxima and minima of quadratic and hermitian 

 forms and its application to a new foundation for 

 the theory of bilinear forms. Krst paper: Equiv- 

 alence of pairs of bilinear forme." 



J. S. Taylor: "The analytic geometry of com- 

 plex variables with some applications to function 

 theory. ' ' 



C. H. Forsyth: "The value of a bond to be re- 

 deemed ultimately, both principal and interest, in 

 equal installments." 



0. H. Forsyth: "Valuation of bonds bought to 

 realize a specified rate of interest assuming the 

 am'ortizabions to accumulate at a savings bank 

 rate. ' ' 



Einar Hille: "Zeros of Legendre functions." 

 W. B. Carver : ' ' Systems of linear inequalities. ' ' 

 J. L. Coolidge: "Differential geometry of the 



complex plane." 



C. L. E. Moore: "Note on minimal varieties in 



hyperspace. ' ' 



1. J. Sehwatt: "Independent expressions for the 

 Bernoulli numbers." 



I. J. Sehwatt: "Relations involving the num- 

 bers of Bernoulli and Euler. " 



I. J. Sehwatt: "Independent expressions for 

 Euler numlbers. ' ' 



I. J. Sehwatt: "Independent expressions for the 

 Euler numbers of higher order." 



I. J. Sehwatt: "Summation of a type of 

 Fourier 's series. ' ' 



F. W. Owens: "On the projectivity assumption 

 in projective geometry." 



R. W. Burgess: "On certain simple skew fre- 

 quency curves." 



G. M. Robison: "Divergent double series and 

 sequences. ' ' 



G. D. Birkhoff: "An extension of Poincarfi's 

 geometric theorem." 



J. L. "Walsh: "On the location of the roots of 

 polynomials. ' ' 



Abstracts of the papers will appear in the 

 March issue of the society's Bulletin. 



The fifteenth western meeting of the society was 



held at Chicago on December 29-30, in connection 

 with the meeting of the American Association for 

 the Advancement of Science. The next regular 

 meeting of the society will be held at New York 

 on February 26. 



B. G. D. Richardson, 



Secretary 



THE AMERICAN ASTRONOMICAL 

 SOCIETY 



The twenty-fifth meeting of the society was held 

 in af&liation with the American Association for 

 the Advancement of Science at the University of 

 Chicago on December 28-30, 1920. In common 

 with other societies there was a full attendance of 

 members, about sixty astronomers being present, 

 and there were many interesting and valuable 

 papers. Sessions were held on three days in the 

 Ryerson Physical Laboratory, but without doubt 

 the most important astronomical communication 

 was presented at the joint session with the Ameri- 

 can Physical Society and the Optical Society of 

 .America, when Professor A. A. Michelson an- 

 nounced the striking success of his interferometer 

 as applied at Mt. Wilson in the direct measure of 

 the diameter of the star a Orionis. 



The members attended a joint dinner at the 

 Quadrangle Club with the members of the mathe- 

 matical societies, and there was the usual profitable 

 intercourse with other men of science made pos- 

 sible at these large gatherings. 



As this was not the annual meeting of the so- 

 ciety, there were no particular matters of business 

 to be considered. A dozen new members were 

 elected, bringing the total membership to some- 

 thing more than three hundred and fifty. 



Following are the titles of the papers, abstracts 

 of which will be regularly published in Popular 

 Astronomy. 



Note on the comparison of spectral types deter- 

 mined at Harva/rd and Mount Wilson: W. S. 

 Adams and A. H. Joy. »■ 



Eviderice regarding the giant and dwarf division 

 of stars afforded by recent Mount Wilson paral- 

 . laxes: W. S. Adams and A. H. Jot. 

 Additional evidence on changes of wave-length 

 which are progressive with stellar type: Sebas- 

 tian Albkecht. 

 Sun-spot intensities as components of a Fourier 



series : Dinsmoke Alter. 

 Tfie association of hydrogen lines with the "in- 

 variable" K line in th^ spectrum of k Vraconis: 

 R. H. Baker. 



