5 4 1 Royal Society : — 



porary suspension of investigations which are now admitted to have 

 been of very high interest ; but by the liberality and public spirit of 

 the British Association, and by the aid of occasional grants of money 

 from the Royal Society, apparatus for their resumption was com- 

 pleted at the Kew Observatory in 1857, and the investigations were 

 recommenced on the 1st of January, 1858. The results obtained 

 from the photographic records of the Kew declinometer in 1858 

 and 1859, with a full description of the methods and processes 

 employed in their elicitation, were communicated to the Royal 

 Society in 1860, and are printed in vol. xxii. of the Phil. Mag. 

 pp. 310-324. The two years which have since elapsed have fur- 

 nished similar results for the years 1860 and 1861, strictly compar- 

 able with those of 1858 and 1859, having been obtained with the 

 same instruments and by the same methods. We have now, there- 

 fore, the observations of four consecutive years from the Kew Ob- 

 servatory, and we are thereby enabled to infer, by the comparison of 

 the aggregate amount of disturbance in each of those years, the pro- 

 gression of the decennial variation up to the close of 1861. The 

 aggregate amounts of disturbance in the four years were severally as 

 follows : — 



1858, January 1 to December 31, 7263*7 mins. of arc. 



1859, „ „ 7637-3 



1860, „ „ 7540-2 



1861, „ „ 6461-6 



The observations of preceding years had led to the expectation that 

 1858, 1859, and 1860 would be the three years of maximum, in which 

 the aggregate amounts of disturbance would differ but little, and 

 that 1861 would be the first year of medium, showing an aggregate 

 amount of disturbance considerably below 1858, 1859, and 1860. 

 This expectation has been realized ; and we have now before us the 

 prospect that the present year, 1862, will prove to be the second 

 year of medium, with an aggregate amount of disturbance nearly 

 resembling that in 1861, but a little less; and that 1863, 1864, 

 and 1865 will be years of minimum, differing little from each other 

 in the amount of disturbance, and all lower than the preceding years 

 1861 and 1862 on the one hand, or the succeeding years 1866 and 



succeeding, 1846 and 1847, 



is well shown by the results of the hourly observa- 



tions made in those years at 



the Hobarton Magnetic 



Observatory. 

















Minutes of arc. 



1841, 

 1842, 



Jan. 



1 to Dec. 



31; 



aggregate 



values 5441-9" 

 „ 4080-8 j 



.4761-4. 



1843, 



» 





tt 





tt 



tt 



2183-4" 



■ 



1844, 



»> 





» 





tt 



tt 



2948-6 



► 2565-2. 



1845, 



»> 





tt 





tt 



tt 



2563-7, 





1846, 

 1847, 



It 





it 

 tt 





it 

 tt 



tt 

 it 



3735-5" 



4883-4 



► 4309-5. 



The aggregate values which are here given are the amounts in each year of the 

 disturbances exceeding 2'-13, reckoned from the normals of the several months 

 and hours. 



