Report of the Keto Committee. 



401 



The Vertical Force Balance Magnet was found to have a scale 

 value of for 1 inch £V= 0*0296, and therefore appeared wanting in 

 sensitiveness, it was accordingly re-adjusted and brought up to the 

 proper pitch of delicacy. 



The values of the ordinates of the different photographic curves 

 determined then were as follows : — 



Declination : 1 inch=0° 22'-04. 1 cm. = 0° 8'7. 



Bifilar, January 11, 1886, for 1 inch £H=0'0268 foot grain unit. 



„ 1 cm. „ =0-0005 C.G.S. unit. 

 Balance, January 19, 1886 ,, 1 inch <5V= 0*0274 foot grain unit. 



„ 1 cm. „ =0-0005 C.G.S. unit. 



The chief days on which notable magnetic disturbance was recorded 

 were as follows : — January 9, March 30, July 27, and October 7—11. 



The magnetic instruments have been studied, and a knowledge of 

 their manipulation obtained by Professor L. M. Russell, Mr. E. Kitto, 

 and Mr. C. Chambers, jun. 



Professors Riicker and Thorpe visited the Observatory in April, 

 and made several sets of observations with the instruments which 

 they have employed in their magnetic survey of the British Isles, 

 prior to their commencing operations on the southern section, which 

 have occupied them during the past summer. 



At the request of the Royal Cornwall Polytechnic Society, a set of 

 magnetographs on an improved model has been constructed for the 

 Committee by Mr. Munro, which, after a lengthened trial in the 

 Verification House, were forwarded to Falmouth, and erected at the 

 New Observatory, under the supervision of Mr. T. W. Baker. The 

 cost has been defrayed by a grant from the Royal Society's Govern- 

 ment Fund. 



At the suggestion of General Sir J. H. Lefroy, the Committee 

 have caused a plate to be engraved on which sectional lines are laid 

 down on the scale adopted by the International Polar Conference, 

 for plotting all magnetic curves on a uniform system. Impressions 

 from this plate will be kept at the Observatory, and supplied at cost 

 price to persons desirous of making use of such forms. 



Information on matters relating to terrestrial magnetism and 

 various data, have been supplied to Professor W. G. Adams, Dr. 

 Atkinson, General Sir J. H. Lefroy, Professor B. Stewart, M. 

 Moureau, Captain Schiick, and others. 



The monthly observations with the absolute instruments have been 

 made as usual, and the results are given in the tables forming 

 Appendix I of this Report. 



The following is a summary of the number of magnetic observations 

 made during the year : — 



