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VIII. Some Phenomena of Magnetic Disturbances at Keu: 



By CHARLES CHREE, Sc.D., LL.D., F.K.S., Superintendent of the, Observatory 

 Department of the National Physical Laboratory. 



(From the National Physical Laboratory.] 

 Received January 5, Head February 10, 1910. 



CONTENTS. 



Sections Page 



1 Introductory 271 



2-6. Non-cyclic changes 273 



7-8. Diurnal variation. Absolute ranges 279 



9-17. Diurnal inequalities from disturbed days 284 



18-22. Fourier coefficients 294 



23-28. Force vector of diurnal inequality 299 



29-34. Comparison of diurnal inequalities at different stations 302 



Introductory. 



1. In the course of the present paper frequent reference is required to two previous 

 papers, termed for brevity (A)* and (C),t which dealt with results derived from the 

 Kew magnetograms of the eleven years 1890 to 1900. 



(A) dealt with results from the Astronomer Royal's "quiet" days only, but 

 included Declination, Inclination, Horizontal Force, and Vertical Force termed 

 sometimes for brevity D, I, H, and V. (C) dealt with declination only, but included 

 results from all ordinary days and from the more highly disturbed days treated 

 separately. Some results which had to be omitted from (C), or which are only 

 glanced at there, were discussed in an appendix termed here (C') attached to the 

 reprint of (C) in Vol. V. of the ' Collected Researches ' of the National Physical 

 Laboratory. 



The present paper is devoted to the phenomena on highly disturbed days, but 



* ' Phil. Trans.,' A, vol. 202, p. 335. 



t ' Phil. TransV A, vol. 208, p. 205. 



VOL. COX. A 466. 10.5.10 



