ME. C. V. WALKEE ON MAGNETIC STOEMS AND EAETH-CUEEENTS. 
91 
these deflections have been a much more common occurrence, even when the other parts 
of the line were unaflected, and when no auroral phenomena were noticed,” — P. 66. 
From the record of ‘ The Daily Observations of Magnetometers at the Eoyal Observa- 
tory, Greenwich, in the year 1847,’ I make extracts, as far as they apply to the notes of 
disturbances quoted above. 
May 8. Decimation magnet. — “ Between 4^ and 6** the change was considerable for the 
time of day.” 
Vertical-force magnet. — “ Between O'* and I'* 50“* and between b'* and 8*^* con- 
siderable changes occurred,” 
Sept. 24. Declination magnet. — “ From O'* to 16** .... the changes were very consider- 
able.” 
Horizontal-force magnet. — “ The changes were very frequent and of large 
amount.” 
Vertical-force magnet. — “ Between O'* and 10'* .... considerable changes 
occurred,” 
Oct. 23. Decimation magnet. — “The changes were frequent and of large amount.” 
Horizontal-force magnet. — “The changes were frequent and of large amount.” 
Vertical-force magnet. — “ Between O'* and 12** the changes were frequent and 
of large amount.” 
October 24. — “ October 23*' 22'* (^. e. 10 a.m. October 24). Bemarkable changes having 
taken place in the positions of the declination and horizontal-force magnets, extra 
observations were commenced ” [they were continued till 23'* 57*** 30\ ^. e. till 11'* 
57-|'** A.M. October 25]. 
Oct. 25. Declination magnet. — “ The changes were frequent and of large amount.” 
Horizontal-force magnet. — “ The changes were frequent and of large amount.” 
Vertical-force magnet. — “ The changes were frequent and of large amount.” 
In the ‘ Extraordinary Meteorological Observations ’ at the same place for the same 
year, an aurora is noted on September 24 from 9.39^ to 10.40^ p.m. 
Seven pages are also occupied with an ample description of the magniflcent aurora of 
Sunday, October 24, An account of this aurora, with a series of coloured engravings, 
was also published at Cambridge by Mr, John Moegan and Mr. T. Baebee. 
The period to which I have been referring was, as is well known, a period of great 
magnetic disturbance. The extent to which these disturbances were manifested in the 
form of current electricity traversing our telegraph wires, may be gathered from the 
following further extract from ‘ Electric Telegraph Manipulation : ’ — 
“ 87. Movable studs. — So much were we inconvenienced during 1848, that I was com- 
pelled to pro\ide a remedy. On the face of the instruments are seen a pair of small 
studs, which are of ivory, and which give a limit to the deflection of the needle ; and if 
by any extraneous cause, and without any act of ours, the needle should be driven hard 
up against one of the studs, our attempt to deflect it in that direction by an ordinary 
signal would not be manifest ; for it is there already. But if under such circumstances 
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