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XIV. Contributions to Terrestrial Magnetism. — No. XII. The Magnetic Survey of the 
British Islands , reduced to the Epoch 1842 - 5. By General Sir Edward Sabine, 
K.C.B . , President of the Royal Society. 
Received June 15, — Read June 16, 1870. 
The Magnetic Survey of the British Islands originated with a few persons interested in 
that branch of experimental science who attended the third Meeting of the British Asso- 
ciation for the Advancement of Science, held at Cambridge in June 1833. 
On his return to Dublin from attendance at that Meeting, Dr. Humphry Lloyd, the 
present Provost of Trinity College, Dublin, who was then its Professor of Natural Phi- 
losophy, proposed to myself, then serving on the Staff of the Army in Ireland, to unite 
with him in an endeavour to realize such an undertaking, by a commencement which 
should be at first limited to Ireland. Fortunately I had with me at the time the 
instruments which I had employed for similar purposes in several arctic and equatorial 
voyages; and being then quartered in the South-West District of Ireland, I found it not 
incompatible with my military duties to undertake the Southern portion of the island, 
whilst Professor Lloyd occupied himself in the Northern portion. Our observations 
were continued at intervals throughout 1834 and until the autumn of 1835, in the 
summer of which year we were joined by Captain James Clark Ross, R.N., who had 
been associated with me in similar undertakings in Arctic countries. 
A provisional report of our operations, drawn up by Professor Lloyd, was presented 
to the British Association assembled in Dublin in 1835, and was printed in 1836 in the 
4th volume of the Reports of the Association. 
Mr. Robert Were Fox, who was present at the Dublin Meeting of the Association 
in 1835, brought with him an apparatus for magnetic observation on a new construction 
of his own invention, which, when the Meeting terminated, he employed in the course 
of a tour in the West and North of Ireland, the results of which were incorporated in 
Professor Lloyd’s report adverted to in the last paragragh. 
In 1836, having obtained two months’ leave of absence from military duties in Ireland, 
I employed them in extending the Survey to twenty-seven stations in Scotland, well 
distributed over that country, and forming the basis of a memoir on the Scottish Isoclinal 
and Isodynamic Lines, which was printed in the fifth volume of the Reports of the Asso- 
ciation, published in 1837. 
In the summer of 1837 Professor Lloyd commenced the magnetic survey of England 
by observations at fourteen stations, principally in the midland and southern districts ; 
and in the same summer Professor John Phillips, who as one of the Secretaries of the 
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