in the Magnetic Forces of the Earth. 



51 



val of time embraced in the above table, cannot be ascribed to a 

 greater average amount of nocturnal radiation resulting from a 

 greater clearness of sky. 



For the years 1841-2, the observations only furnish the aver- 

 ages for the entire day, of twenty-four hours. These, with the 

 averages for 1843 and 1844, and from January to June, 1845, are 

 as folio ws : 



1841. 



•63 

 •56 



•48 

 •59 



1842. 



55 



•49 

 •52 

 •44 



1843. 



59 



75 

 79 



1844. 



•80 

 •92 

 •70 

 •67 



1845. 



•65 

 •72 



Jan., Feb., March, . 

 April, May, June, 

 July, Aug., Sept., . 

 Oct., Nov., Dec, 



These numbers serve only to confirm and extend the conclusion 



drawn from the previous table. 



The following table, giving for each quarter of the year the 



mean number of days, during the years 1839, 1840-1, and parts 



of 1838 and 1842, on which the wind prevailed, at 9 p. m. and 



3 a. >i., from each direction, at Washington, will furnish the 



means of judging of the influence of particular directions of the 

 wind. 



January, <fcc. 



April, &c. 



• • • 



July, <fec, 



October, <fcc. 



Entir 



e year, 





1 N ' 



N.E. 



E. 



S.E. 

 5 



1 s - 



| s.w. 



w. 



| N.W. 

 15 5 



Calm. 



9 P. M. 



61 



100 



75 



12 3 111 



8-5 



155 



3 A. M. 



61 



10-7 



60 



30 



11-8 



115 



60 



16-8 



178 



9 P. M. 



46 



97 



33 



80 



110 



8-7 



9 3 



116 



22*8 



3 A. M. 



4-8 



13-7 



46 



8-3 



60 



120 



96 



110 



192 



9 p. x. 



56 



50 



40 



7-3 



97 



90 



105 



111 



21-6 



3 a.m. 



62 



109 



57 



36 



54 



143 



93 



110 | 200 



9 p. m. 



6-8 



123 



7-8 



2-7 



&8 



110 I 



1 8-8 



190 



! 168 



O A. M. 



95 



120 



1 69 



42 



3-8 



97 



77 



22-4 



174 



9 P.M. 



231 



370 



226 



230 



398 



398 



37*1 



572 76-2 J 



3 A. M.I 



266 



473 



232 



191 



26-5 



475 



326 



61-2 J 



744 1 



Prom this table we derive the following, showing the relative 

 frequency of the cold and warm winds. 



January, &c. 

 October, &c. 



9 P. M. 

 3 A. M. 

 9 P. M. 

 O A, M. 



April, &c. 

 J «ly, &c. 



9 P. M. 



3 A. M. 

 9 P. M. 



O A. M# 



Entire year. 



9 P. M. 

 3 A. M. 



N., N.E., W.. N.W 



401 . 

 . 396 



469 . 

 . 516 



N.,N.W.,N.E., E. 



292 . 



. 341 



25-7 . 

 . 33 8 



K. N.W., N.E. 



117-3 . 

 . 1351 



. 35-9 

 31-8 



. 28-3 

 24-6 



8., If., S E., E. 



. 370 

 35-9 



. 36-5 

 32-6 



. 102 6 

 931 



On examining these tables, it will be seen that calms are about 

 equally frequent before and after midnight, and that cold winds 



are rather more frequent and warm ones less so, throughout the 



