ASTRONOMY — llAht. '5 



within the near future. The work commenced on the radiation of the 

 7acul^, which are found to give large deflections when near the suns 

 limb, will also be continued and extended. 



STELLAR SpECTROSCOPV. 



The investigations undertaken last year, in collaboration with Mn 

 Adams wth ^he object of ascertaining whether very h,gh d.spers on 

 tuWbe^uccessfully used in photographing the spectra of br.ght stars, 

 have been ontnued with satisfactory results. It has been found as 

 win That there should be no serious difficulty in photographmg 

 S th t *ch efl t:' the spectra of several of the briglrtest stars on 

 Tscale qual to that employed by Rowland in his work on the solar spec- 

 rum Such spectra, if obtained of the desired sharpness. ^1'-" prov of 

 the^reatest service in our study of stellar evolution, smce all of the prm 

 laf stellar types, with a single exception, are represented among the 

 bright sta which are likely to fall within the range of this mvesuga- 

 tion The work with the Snow telescope has consisted mau.ly of a con - 

 parative study of the relative merits of gratings and pr.sn or t 

 Lrk with the advantages decidedly in favor of prisms. It ="'' ■•»;«•" 

 uncertain whether prisms of sufficiently large d.naensions, and o he 

 neces ary homogeneitv, can be obtained, but we have hopes that the 

 difficult es expeifenced in the case of our 30-foot spectroheUograph may 

 u" y be over ome.. The spectra of Arcturus. photographed with the 

 Xs Ld prisms have P-ed usefuUn a s^^<iy of t e su^^spot Jines 



irs;:nrs'::g: io:: LT.-SworktTheUu^m oi « oHoms 



which showed that the lines which are about equally prominent in the 

 Tprr;" Us and in that of A^rus are^ —^^^^^^ 



=tlV"vrcnbtl:d"r:rea2r ^ of - stars 



wTth theT-inch Yerkes telescope, is strongly confirmatory of the view 

 rhtth: absorbing atmospheres of these stars are lower - tem^er'u e 

 than that of the sun. leading to the inference that they ^« J" "" 



* See page 68. 



] Contributions from the Solar Observatory, No. 12. 



