( 457 ) 



Table, showing the Mean Monthly Westerly Declination of the Magnet, and 

 the Mean Dip, at the Greetvwich Boyal Observatory , from 1844 to 1891. 



Mouth. 



1844 



1850 



1860 



1870 



1880 



1885 



January . 

 February . 

 March .... 



April 



May 



June 



July 



August .... 

 September 

 October.... 

 November 

 December . 



Means .... 

 Mean Dip , 



23 19 22 

 28 18 48 

 28 18 42 

 28 18 42 

 28 19 23 

 19 8 

 18 40 

 23 13 25 

 23 13 6 

 22 12 52 

 22 11 50 

 22 49 41 



23 

 23 



22 28 5 

 22 27 28 

 22 26 54 

 22 25 44 

 22 25 1 

 22 24 47 

 22 28 41 

 22 22 4 

 22 25 43 

 22 19 1 

 22 18 27 

 22 18 27 



53 

 4 



23 4 28 



22 23 47 



68 46-9 



21 14 38 

 21 13 2 

 21 14 

 21 15 

 21 17 10 

 21 16 1 

 21 15 44 

 21 15 27 

 21 12 44 

 21 13 28 

 21 li! 49 

 21 11 30 



19 57 28 

 19 56 44 

 19 56 21 

 19 55 6 

 19 54 50 

 19 52 52 

 19 52 57 

 19 52 16 

 19 51 55 

 19 51 

 19 51 



40 

 18 



19 50 26 



21 14 22J 



19 53 39 



68 30-1 



67 52-6 



18 

 18 

 18 

 18 

 18 

 18 

 18 

 18 

 18 

 18 

 18 

 18 



34-7 

 34-8 

 341 

 33-5 

 32-2 

 31-8 

 320 

 32-6 

 32-3 

 321 

 30-9 

 30-7 



18 32-6 



67 35-6 



18 

 18 

 18 

 18 

 18 

 18 

 18 

 18 

 18 

 17 

 17 

 17 



4-8 



4-3 



3-7 



31 



2.6 



1-9 



1-5 



1-5 



0-5 



59-4 



59-7 



57-4 



18 1-7 



67 27-8 



Month. 



January . 

 February . 

 March .... 



April 



May 



June 



July 



August .... 

 September 

 October.... 

 November 

 December . 



Means .... 

 Mean Dip . 



1886 



17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 



56-3 

 55-4 

 65-6 

 55-2 

 54-9 

 55-2 

 55-4 

 54-2 

 540 

 53.0 

 52-8 

 62-5 



17 54-5 



67 270 



1887 



17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 



520 

 51-6 

 51-7 

 50-7 

 50-5 

 50-6 

 49-5 

 48-9 

 47-4 

 47-1 

 44-6 

 44-1 



17 491 



67 26-4 



1888 



1889 



17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 



42-7 



42-4'' 



41-9 



40-9 



40-9 



40-8 



40-5 



39-4 



39-3 



39-5 



38-3 



37-8 



17 40-4 



67 25-4 



17 



17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 



380 

 36-9 

 36-4 

 35-3 

 34-7 

 35-3 

 340 

 33-9 

 34-3 

 33-4 

 32-7 

 33-4 



17 34-9 



67 24-1 



1890 



17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 



31-7 

 31-1 

 30-5 

 29-6 

 28-9 

 28-6 

 27-4 

 27-9 

 27-7 

 27-2 

 26-3 

 26-2 



17 28-6 



1891 



17 

 17 



17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 

 17 



25-8 

 24-7 

 24-5 

 24-8 

 24-4 

 24-2 

 23-3 

 231 

 22-2 

 21-8 

 21-2 

 205 



17 23-4 



67 22-9 67 21-4 



(470.) Upon examining these columns of figures, it will be seen that the 

 decreasing amount of Westerly Variation is far from being regular, and 

 that at some periods the Variation is absolutely increasing. The mean 

 Variation in 1891 was about 17° 23-4', so that it had decreased 5° 41' in 

 the forty-seven years elapsed since 1844, or at the rate of 7^' per annum ; 

 but its mean rate at Greenwich is about 5^' or 6' at present, according to 

 the most recent observations at the Greenwich Observatory, varying 

 irregularly from 5' to 8^' between successive years. 



N.A.O. 69 



