ON THE MAGNETIC INTENSITY OF THE EARTH. 23 
Finmarken, and Spitzbergen, all which are inserted in the ge- 
neral table. 
Hansteen and Due, Erman, 1828-1830.—In 1819 M. Hans- 
teen published his celebrated work on the magnetism of the 
earth, in which he brought into one view a larger body of 
observations of the dip and variation than had been brought 
together by any previous philosopher ; and by subjecting them 
to a close examination, drew this remarkable inference in re- 
gard to the intensity; namely, that a centre, or pole as it 
might be termed, of magnetic intensity must exist in the north 
of Siberia, less powerful, but otherwise similar to the one in 
the north of America; and that the lines of equal intensity 
would be found to arrange themselves around the Siberian 
centre in the same way as around the centre of greater force in 
America. At the time M. Hansteen drew this inference not a 
single observation of the intensity had been made nearer to 
Siberia than Berlin on the one side and Mexico on the other. 
M. Hansteen’s work, much more read on the Continent than 
in England, produced a very general desire that an inference 
so remarkable, and so important if confirmed, should be sub- 
mitted to the test of experiment, This, however, exceeded in- 
dividual means to accomplish; it was one of those underta- 
kings in science for which national aid is required. To the 
honour of Norway, the funds for this undertaking were fur- 
nished by a unanimous vote of the Norwegian Storthing or 
Parliament. In 1828 M. Hansteen, accompanied by Lieut. 
Due, proceeded at his country’s expense, and with every faci- 
lity which could be afforded him by the Russian Government, 
on a journey expressly for magnetic observations through the 
Russian dominions in the north of Europe and Asia, They 
were provided with a dip circle and two needles of Gambey’s, 
and with M. Hansteen’s apparatus for horizontal vibrations. 
At St. Petersburg they were joined by M. Erman of Berlin, 
proceeding on a similar mission to the same countries, and 
similarly furnished with magnetic instruments. The three 
gentlemen travelled together to Siberia, MM. Hansteen and 
_ Due on the one part, and M. Erman on the other, making the 
same observations everywhere, but independently of each other. 
They wintered at Irkutsk ; and the following year MM. Hans- 
teen and Due returned to St. Petersburg by land route, and 
M. Erman proceeded by Ochozk to Kamtschatka, where he 
embarked for Europe. The maps attached to this memoir 
mark by the observations entered on them their various jour- 
neys, separately and together, in northern Asia. Suffice it 
