REPORT OB^ THE SECRETARY. 



83 



KESULTS IN DETAIL. 



Referrinfr to my report of la^;t year and to your recent {)nl)lication " on "A possible 

 variation of solar radiation" for further inforniation, tlie following three tables suni- 

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

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

 only to remark concerning them that the firstsix 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' 

 work 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. — Coejficients of afinosplteric transmismm for radiation from zenith suit. 



Wave length . 



Date. 



1.60 



Transmi.ssion coefficients for unit air mass. 



July 7 



August 24 



September 14. 

 October 14 . . . 

 October 29 . . . 

 December 7 . . 

 December 23 . 



11 

 .lanuary '2~ ... 

 February 11 .. 



April 4 



April 21 



May 12 



May 28 



General mean 



Mean, July 1, 1903, to Jan- 

 uary 1, 1904 



Mean, January 1, 1904, to 

 July 1, 1904 



0.69 

 .69 

 .i2 

 .80 

 .75 

 .82 

 .79 



.73 

 .59 

 .72 

 .67 

 .79 

 .77 



0.85 

 .86 

 .91 

 .89 

 .83 

 .89 

 .90 



90 



84 

 88 

 85 

 89 

 90 



876 

 .876 

 .876 



0.89 

 .90 

 .93 

 .92 

 .01 

 .95 

 .94 



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



