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XL Records of the Magnetic Phenomena at the Kew Observatory. — No. IV. Analysis 
of the principal Disturbances shown by the Horizontal and Vertical Force Magne- 
tometers of the Kew Observatory , from 1859 to 1864. By General Sir Edward 
Sabine, K.C.B . , President. 
Received June 15, — Read June 15, 1871. 
This paper contains an analysis of the first portion of the Automatic Records obtained 
at the Kew Observatory by means of the self-recording Horizontal and Vertical Force 
Magnetometers devised by the late Superintendent of that Observatory, Mr. John 
Welsh, aided by Mr. Beckley, Engineer in that establishment. 
The Record of the Horizontal Force commenced on the 1st of January, 1858, and that 
of the Vertical Force a year later, viz. on the 1st of January, 1859. The present notice 
includes the records of both to the 31st of December, 1864, — making seven complete years 
of the Horizontal Force, and six complete years of the Vertical Force. The daily Pho- 
tograms, from which the results have been derived, are carefully preserved at the Obser- 
vatory, and hitherto, at least, appear to have suffered little or no deterioration. The ap- 
paratus and methods by which the photograms are obtained have been already fully de- 
scribed. The Observatory had the great misfortune of losing the Superintendence of 
Mr. Welsh by his decease in 1859; but the instruments and methods which he had so 
ably devised, have continued and still continue in use, unchanged. It was originally 
his intention to discuss the results obtained with the self-recording magnetic instru- 
ments in successive periods, each of six years, beginning with 1858 ; but in conse- 
quence of the illness which preceded his death, no preparations had been made for the 
commencement of this work. The photograms were indeed preserved with all suitable 
care, but were liable, as must necessarily be the case even under the most favourable 
conditions, to deterioration. Under these circumstances I ventured in 1862 to propose 
to Mr. Gassiot, Chairman of the Kew Committee (of which I was myself a member), 
that the photograms of the First of the Periods contemplated by Mr. Welsh, viz. from 
January 1, 1858, to December 31, 1864, should be entrusted to me, to be tabulated 
by the non-commissioned Officers at the Woolwich Magnetic Office, and subsequently 
discussed by myself on the same plan as the Eye-observations at the Colonial Magnetic 
Observatories had been discussed. This arrangement, so far as the tabulation was con- 
cerned, was speedily effected, and the Photograms were forthwith returned for safe 
custody to Kew, where they remain and are in good preservation. My own time, and 
that of the Office, having been much occupied latterly in preparing the Maps of the 
Magnetic Elements corresponding to the Epoch of 1842.5, the deductions from the Pho- 
tograms, from January 1858 to December 1864, have not been completed at so early a 
sidccclxxi. 2 u 
