Report of the Kew Committee. 4o3 



The values of the ordinates of the different photographic curves 

 determined in January were as follows : 



Declination : 1 inch=0 22'-04. 1 mm.=0 0''87. 



Bifilar, January 4, 1884, for 1 inch <$H=O0276 foot grain unit. 



,, 1 mm. ,, =0*0005 mm. mgr. unit. 

 Balance, January 4, 1884 1 inch eV=Q'0251 foot grain unit. 



,, 1 mm. =:0'0005 mm. mgr. unit. 



The distance between the dots of light upon the cylinders of both 

 the Bifilar and Vertical Force Magnetometers having become too 

 small for satisfactory registration, it was found necessary to readjust 

 each instrument, after which the scale values were again determined 

 on January llth, with the following results : 



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. 



Bifilar for 1 incli H=0'0267 foot grain unit. 



,, 1 mm. ,, =0'0005 mm. mgr. unit. 

 Balance 1 inch V=0'0296 foot grain unit. 



1 mm. =0'0005 mm. mgr. unit. 



The tabulation referred to in last year's Report of the traces of the 

 three magnetic elements for the International Polar Commission, is 

 now completed, and the conversion of the results into absolute units 

 is in an advanced stage. 



The difficulty experienced in adapting ordinary unprotected gas 

 burners to the Bifilar and Balance Magnetometers, owing to the 

 extremely sensitive nature of the gelatino-bromide paper, has now 

 been overcome by the use of a small screen of blue glass interposed 

 between the flame and mirror. This diminishes the intensity of the 

 light, so that the traces are now well defined instead of being blurred. 



Information on matters relating to terrestrial magnetism, and 

 various data, have been supplied to Dr. Wild, General Tillo, Dr. 

 Frolich, Admiral Sir G. Richards, and Dr. Balfour Stewart. 



The various magnetic instruments returned by Captain Dawson, 

 R.A., on his arrival in this country from the Fort Rae Circumpolar 

 Expedition, were lent, with the exception of the Balance Magneto- 

 meter, one Bifilar, and one Declinometer, to Lieutenant A. Gordon, 

 R.N., of the Meteorological Office, Canada. 



Professors Riicker and Thorpe visited the Observatory on July 17, 

 18, and 19, for the purpose of taking a series of absolute magnetic 

 observations preparatory to surveying the western coast of Scotland, 

 as a preliminary operation towards the proposed repetition of the 

 Survey of Great Britain and Ireland mentioned in last Report. 



