Cuar, VIL, § 8.] ELECTRICITY (MAGNETISM).—GENERAL SABINE—SIR J.C. ROSS. 995 
On the whole, itis no small praise to say that the 
longs, the difficulty of starting simultaneously sys- 
907. 
Pn ) great geometer of Gittingen occupies the same rank tematic observations (with instruments new and little 
Cental in the theoretical science of terrestrial magnetism as understood, and dispersed to the widest possible ex- 
His death. 
Kepler did in the theory of astronomy. That a per- 
son devoted for the greater part of his life to pursuits 
connected with the most abstract geometry, should 
have at last thrown himself with so much zeal into 
the practical solution of a complicated experimental 
problem, is a circumstance as rare as it is praise- 
worthy. Gauss lived long enough to see his methods 
adopted all over the world, and his name honoured 
amongst every civilized people. Gauss died at Got- 
where he had resided since 1807), in great 
tent over the surface of the globe), was evidently very 
great. Canada, St Helena, the Cape of Good Hope, 
and Van Diemen’s Land, were selected for primary 
stations ; and the vastly voluminous results of hourly 
or two-hourly observations of numerous instruments 
continued year by year came pouring in to the central 
establishment at Woolwich under General Sabine’s 
presidency. Besides these, several nautical expedi- 
tions were fitted out for similar purposes, the most 
important of which was sent in 1840 under the direc- 
tranquillity, on the 23d February 1855, in the 78th 
year of his age. . 
tion of Sir James Clark Ross to approach as nearly Captain 
as might be to the Antarctic Pole. This voyage, whe- eee o 
ther in respect of the spirit of adventure displayed, ~~ 
(908.) 
Import- 
ance of 
national 
expedi- 
tions, 
But to obtain the data of the empirical theory with 
exactness, it is evident that expeditions fitted out ex- 
pressly with accurate apparatus, and directed at once 
to many points of the habitable globe, are indispen- 
sable. Powerful governments can alone effect this ; 
and to Baron Humboldt is due (as has been shown) 
the praise of having vigorously pressed the import- 
ance of these upon the governments of England and 
of Russia. The vast marine resources of the former, 
and the peculiar magnetic interest of the stupendous 
Asiatic territory of the latter, rendered their co- 
operation highly important. In the result, Great 
Britain has accomplished by far the larger share of 
this vast enterprise. 
the wonderful character of the natural objects re- 
vealed by it for the first time to human view, or the 
importance of the scientific results obtained, may 
rank with any of our memorable polar expeditions, 
By the aid of an ingenious instrument contrived by 
Mr Fox, trustworthy magnetical observations were 
made on dip and intensity (as well as on declina- 
tion) even in the open sea, and thus the area contri- 
buting to our knowledge of the earth’s magnetism 
was vastly increased. The results of these researches 
properly reduced have been gradually laid before the 
world by General Sabine in a series of memoirs of 
the utmost’ interest, contained in the Philosophical 
Transactions from 1840 to the present time. 
To Major-General Epwarp Saxinz, of the Royal 
Artillery, is mainly due the judicious management of 
these magnetic explorations, and the speedy and skilful 
publication of their interesting results. During the 
course of an active life he has enjoyed opportunities 
With regard to the geographical phenomena of 911.) 
magnetism, it may now be inferred almost with cer- Geogra- 
tainty that the position of the Antarctic magnetic pole see 
is in a region hitherto inaccessible, and to the south oyives of 
of New Holland, placed somewhere near longitude intensity. 
(909.) 
General 
Sabine. 
(910.) 
British 
of making extensive observations with magnetic ap- 
paratus and with the pendulum (238) throughout a 
greatrange of latitude. His experiments (carried on 
principally between the years 1819 and 1826) were 
made in Brazil, the coast of Guinea, Spitzbergen, and 
Arctic America. His observations on magnetic inten- 
sity are particularly valuable, and first indicated the 
position of a region of maximum intensity in North 
America considerably to the south of the magnetic 
pole as indicated by the dipping needle. To him 
we also owe a valuable Intensity Chart of the Globe, 
and a Magnetic Survey of the British Islands, pub- 
lished in the reports of the British Association for 
1836 and the two following years. 
But his efforts in promoting and directing the 
system of national magnetical research set on foot at 
magnetical Baron Humboldt’s instigation are of still greater 
150° E., and probably not within 17° of the pole of 
the earth, a latitude which was reached by Sir James 
Ross in a longitude somewhat farther east.1 It ap- 
pears also that in the southern as in the northern 
hemisphere there are two centres of greatest intensity, 
round which the curves of equal intensity form ovals, 
and afterwards loops like lemniscates, The stronger 
magnetic centres of. each hemisphere are near, though 
apparently not coincident with, the two proper mag- 
netic poles. The following numbers approximately re- 
present on a scale of absolute intensity (898), in which 
the grain, the foot, and the second are units, the 
magnetic force at the four centres just mentioned; 
the second column contains the corresponding values 
on Baron Humboldt’s scale, mentioned in Art. 885, 
On Humboldt’s Seale, 
- 142 se 1:88 
Atos? 
In North America, . . 
a aa importance, to which, in its earlier stages, the exer- In pepe Eee Ce ure 
: ae : South from New Holland, . 
tions of Dr Lloyd (550) were also of essential service. The other Antarctic centre, 14-9 1-97 
Although seconded by young, able, and enthusiastic 
officers of the service to which General Sabine be- 
The absolute intensity at St Helena, which is not far 
1 See General Sabine’s Charts in Phil, Trans., 1844. 
