EEPOET OP THE SECRETARY. 



79 



Table 2a. — Solar constant values from ■pi/rJielioinetry — Continued. 



Range of i 



air i Log. a 

 masses. 



a- 



Radia- 

 tion com- 

 puted 

 from 

 pyrheli- 

 ometry. 



813 



2.02 



771 



2.27 



7.57 



2.24 



69.5 



2.05 



7.59 



2.25 



796 



2.22 



748 



3.17 



716 



2.30 



865 



2.06 



803 



1.95 



855 



2.24 



857 



2.07 



800 



2.12 



816 



2.23 



703 



2.17 



773 



2.21 



706 



2.18 



774 



2.09 



785 



2.14 



745 



2.22 



802 



3.17 



724 



2.28 



Grade of 

 pyrheliom- 

 etry obser- 

 vations. 



Radia- I 

 tion com-i 

 puted by Grade of spec- 



spectro- tro-bolometric 



bolo- 

 metric 

 m^ethod. 



observations. 



1904. 



January 27 



February 11 . . 



May 28.. 



July 8--- 



September 15 . 

 September 32 . 



October 4 



October 5 



October 21--. 

 November 16 . 

 December 29 _ 



1905. 



January 26 



February 7 



March 2- 



Aprilig 



April 22 



May 2 



May 8 



May 20 



June 3- 



June 22 



June 37 



1.9-4.0 

 1.7-2.9 

 1. 1-1. 9 

 1.2-1.7 

 1.4-2.0 

 1.4-3.0 

 1.7-3.2 

 1.5-2.7 

 1.6-3.0 

 2.0-3.8 

 .2.4-3.6 



1.9-3.4 

 1.8-3.4 

 1. 6-2. 6 

 1.2-2.0 

 1.3-2.1 

 1.3-2.0 

 1.3-2.0 

 1.2-1.6 

 1.1-3.2 

 1.1-2.0 

 1.1-1.5 



.090 

 .113 

 .131 

 .158 

 .130 

 .099 

 .136 

 .145 

 .063 

 .095 



.067 

 .097 

 .088 

 .184 

 .112 

 .1.51 

 .111 

 .105 

 .128 

 .096 

 .140 



Excellent _ _ 

 Very good . 



do. 



do 



Good-. 



Poor 



do 



Very good . 



Fair 



Very good . 

 do 



Excellent . 

 Very good 



Poor 



Passable .- 



Fair 



Excellent . 



Fair 



Poor 



do 



Very good 

 Poor 



2.02 

 3.36 

 3.09 



3.33 

 3.04 

 1.98 



3.04 



Fair. 



Do. 

 Poor. 



Excellent. 



Good. 



Passable. 



Good. 



2.18 



Indifferent. 



(b) Transmission of the solar envelope.—A^ stated above the apparatus for 

 examining the solar image has been provided with appropriate shelters, and 

 IS novi^ much improved over its condition last year. The great coelostat was 

 exhibited at St. Louis in 1904, and as a substitute a smaller coelostat was 

 arranged at the Observatory shop. The larger coelostat was not returned from 

 St. Louis until January, 1905, and, in the press of preparation for the Mount 

 Wilson expedition, time could not well be spared to set it up, so that the smaller 

 instrument has served throughout the year. Many measurements, both of the 

 distribution of radiation along the diameter of the solar disk and of its distri- 

 bution ia sun spots, have been made after the manner explained last year.« A 

 revision has been made of all the data obtained relating to the distribution along 

 ti diameter, on the assumptions (1) that we study a phenomenon of absorption 

 only; (2) occurring in a homogeneous medium situated outside the photosphere, 

 find (3) extending to 21 per cent of the solar radius. 



With these assumptions it appears that the form of the distribution curves as 

 shown in Plate VIII of last year's report agree within the experimental error 

 with that deduced from the ordinary simple exponential absorption formula. 

 As this formula In a logarithmic form is peculiarly adapted to graphical illus- 

 trations and comparison of results, all the measurements have been reduced ou 

 the above basis and the results to be given below in Table 3 depend on it. It 

 goes without saying that the assumptions made are not harmonious with our 

 conceptions of the sun's absorbing envelope, and they are only made for want 

 of better and for the sole purpose of more readily comparing the results of dif- 



« Smithsonian Report for 1904, p. 85. 



