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XVI. Contributions to Terrestrial Magnetism. — No. XIII. 
By General Sir Edward Sabine, K.C.B . , V.P.B.S. 
Received June 19, — Read June 20, 1872. 
In this, the XIII. th Number of the “ Contributions to Terrestrial Magnetism,” I have 
the pleasure of presenting to the Royal Society the Magnetic Survey of the North Polar 
Regions of the Globe, in a suitable form and arrangement to entitle it to be regarded 
as a companion to the Magnetic Survey of the South Polar Regions, presented to the 
Society in 1868 ; constituting, with the present contribution, a moiety of the Magnetic 
Survey of the Globe corresponding to the general epoch 1840 to 1845. The area com- 
prised in the present communication is coextensive with that of the South Polar Survey, 
and the epochs are the same, viz. 1840 to 1845, or more simply 1842*5 ; the chief 
distinction between the two surveys being, that the South Polar Survey is the work of a 
single nation, — executed by the authority of its Government and at the national expense 
in the brief interval comprised between the years 1840 and 1845, and thus requiring 
no corrections to be introduced for secular change, a troublesome and not very certain 
operation ; whilst its companion, the present communication, comprehends the coopera- 
tive labours of many European and American contributors, acting for the most part 
independently of each other, within the limits of about twenty years preceding, and 
twenty years following, the mean epoch of 1842*5 : the results, therefore, when 
brought together, require the introduction of “ corrections for secular change,” where 
these are practicable, and where they can be made with safety. 
The general form in which the observations collected in this Contribution are arranged 
is that of zones — each zone comprehending the observations of successive five degrees 
of latitude, in all longitudes, commencing with Greenwich as the first meridian and 
proceeding easterly until the circumference of the globe is completed. The zones are 
eight in number : — 
Zone 1, comprehending from 
latitude 40° N. to latitude 45° N. 
Zone 2, 
55 55 
45 3 N. 
„ 50° N. 
Zone 3, 
55 55 
50° N. 
„ 55° N. 
Zone 4, 
55 55 
55° N. 
„ 60° N. 
Zone 5, 
55 55 
60° N. 
„ 65° N. 
Zone 6, 
5 5 55 
65° N. 
„ 70° N. 
Zone 7, 
55 55 
70° N. 
„ 75° N. 
Zone 8, 
55 55 
75° N. 
„ 80° N. 
Zone 8 includes also 
the few observations 
in latitudes exceeding 80° N. 
3 D 
MDCCCLXXII. 
