REPORT OF THE SECRETARY, 



83 



RESULTS IN DETAIL. 



Referring to my report of Jast^ear and to your recent publication « on "A possible 

 variation of solar radiation" for furtlier information, the following three tables sum- 

 marize the detailed results of the work already broadly discussed. Tables 1 and 2 

 are given in continuation of similar tables in last year's report, and perhaps it needs 

 only to remark concerning them that the first six months of 1904 have proved uncom- 

 monly unfavorable to such studies as are here set forth, by reason of unusual cloudi- 

 ness. Owing to the bad atmospheric conditions there have been no days when 

 results as satisfactory as many of those of 1903 have been secured, and only two days' 

 woi-k of 1904, February 11 and May 28, are regarded here as worthy of much confi- 

 dence. Taking the whole series together and comparing with the results of 1902-3, 

 it appears probable, however, that excepting during the month of February, the solar 

 radiation thus far in 1904 has been below the normal, although not so low as during 

 the latter half of 1903. The atmospheric transmission of 1903-4 seems to be generally 

 below that of 1902. 



Table 1. — Coefficieniti of utmoRpheric transmission/or radinf inn from zenith sun. 



Wave length . 



Transmission coefficients for unit air mass. 



.Inly 7 



.■\ugust 24 



.September 14. 

 October 14 . . . 

 October 29 ... 

 December 7 . . 

 December 23 . 



11 

 .la!iuary 27 . .. 

 February 11 . . 



April 4 



April 21 



May 12 



Mav28 



0.42 

 .40 

 .52 

 .04 

 .53 

 .59 

 .64 



.60 

 .42 

 .42 



General mean 



Mean, July 1, 1903, to Jan- 

 uary 1, 1904 



Mean, January 1, 1904, to 

 July 1, 1904 



0.60 

 ..51 

 .71 

 .70 

 .59 

 .65 

 .70 



.67 

 .56 

 .63 

 .45 

 .55 

 .57 



.637 



0.89 

 .90 

 .93 

 .92 

 .91 

 .95 

 .94 



.920 

 .930 



«Astrophysical Journal, June, 1904. Phil. :Mag., July, 1904. 



