334 



REPORT — 1887. 



been calculated, and analysed as disturbance east and disturbance west, 

 sustain these conclusions. 



If we could assume that the magnetic pole has travelled about 

 200 miles in a N.N.E. direction since 1831, and is now situated near 

 the bottom of Prince Regent's Inlet, it would appear strikingly that the 

 circle bounding the prevalence of westerly excess of disturbance is definite, 

 and has a radius of about 700 miles round such a centre. 



I am indebted to Brigadier-General Greely for the data in MS. for 

 the curve for Fort Conger, which belongs to the year 1881-2, the fuller 

 results for the year 1882-3 not having yet reached me. It appears, how- 

 ever, from their discussion by Mr. C. A. Schott ('Science,' March 4) that 

 'the most characteristic feature of the solar-diurnal curve (for the whole 

 year) is the occurrence of the westerly extreme soon after local noon, with 

 a deflection of 37' '9 reached earlier in summer and later in winter. The 

 opposite extreme is reached an hour and a half after midnight, with a 

 deflection of 27''9, also found variable with the season.' ' The disturbing 

 force deflecting the N. end of the magnet to the E. is most active two 

 houi-s after midnight and least active during the hours noon to 5 P.M. 

 On the other hand deflections to the west appear most frequent three 

 hours after noon and least about the hours near midnight. Respecting 

 intensity of action, easterly disturbances slightly exceed westerly ones.' 



These conclusions are cori'oborated by the interpolated curve here 

 laid down for the six winter months of 1881-2, although based upon only 

 sixteen days of hourly observation, two or three in each month. The 

 numerical values are taken from the oflicial publications in each case, 

 except Fort Conger and Fort Confidence, for which they are as follows : — 



Appendix VI. Luni-svlar Variation of the vertical Magnetic Force at Bom- 

 hay. Bij Charles Chambers, F.B.8., Director of the Colaha Ohserva- 

 tory, Bombay. 



An account of the luni-solar variations of declination and horizontal 

 force, derived from the registrations of the Colaba magnetographs for 

 the single quarter, November 1875 to January 1876, appeared in the 

 Report of the British Association for 1886, pages Si to 97 ; and the regis- 

 trations of the vertical force magnetograph for the same period have 

 since been treated in the manner there described, and with the results 

 shown in the following table : — 



