318 



Rev. S. J. Perry on Magnetic 

 Table I. (continued). 



[Nov. 16, 



Winter 

 months. 



1870-71. 



1871-72. 



1872-73. 



1873-74. 



1874-75. 



1875-76. 



Mean 

 of six 

 years. 





69 38 25 



69 27 52 



69 31 50 



69 29 37 



69 26 36 



69 18 48 



69 28 51 



November , . . 



38 22 



29 53 



31 22 



30 15 



27 17 



19 58 



29 31 



December 



38 17 



30 59 



32 27 



33 6 



[ 26 55] 



21 48 



30 35 





40 8 



32 13 



30 28 



29 11 



26 32 



25 45 



30 43 



February 



35 26 



32 45 



31 36 



25 36 



21 35 



24 25 



28 34 





31 53 



34 53 



30 20 



29 19 



24 39 



24 25 



29 15 







69 37 5 



69 31 26 



69 31 21 



69 29 31 



69 25 36 



69 22 32 



69 29 35 





Yearly means 



69 37 32 



69 32 13 



69 31 9 



69 30 5 



69 26 7 



69 22 5 



69 29 52 



The numbers for September and December 1874 are interpolated. 

 We have therefore for April 1st, 1873, 



The mean dip = 69° 29' 52", 



With a secular variation = — 3' 5" "4. 



The amount of annual diminution from the preceding seven years' 

 observations was only 1' 49"'2 ; the dip would therefore appear to be de- 

 creasing more rapidly at present ; but the value —2'* 15, given last year 

 by the Kew results, shows that the Stonyhurst number is probably too 

 large. 



Table II. — Semiannual inequality of the Dip. 



Date. 



July 1, 1870 



Jan. 1, 1871... 

 Julyl, 1871 



Jan. 1, 1872... 

 July 1, 1872 



Jan. 1, 1873... 

 July 1, 1873 



Jan.l, 1874... 

 July 1, 1874 



Jan.l, 1875... 

 July 1, 1875 



Jan. 1, 1876... 



Correction 

 for secular 

 variation. 



+8 30 

 +6 57 

 +5 24 

 +3 52 

 +2 19 

 -f 46 

 -0 46 

 -2 19 

 -3 52 

 -5 24 

 -6 57 

 -8 30 



Mean 

 Valae 

 + secular 

 variation. 



69 38 22 

 36 49 

 35 16 

 33 44 

 32 11 

 30 38 

 29 6 

 27 33 

 26 

 24 28 

 22 55 

 21 22 



Observed 

 Values. 



69 37 58 

 37 5 

 32 59 

 31 26 



30 56 



31 21 

 30 39 

 29 31 

 26 38 

 25 36 



21 38 



22 32 



Observed — Computed. 



Summer. Winter. 



-0 24 

 -2 17 

 -1 15 

 + 1 33 

 +0 38 

 -1 17 



+0 16 

 -2 8 

 +0 43 

 -fl 58 

 +1 8 

 4-1 10 



Mean differences in the semiannual periods —0 30 



H-O 31 



