GENERAL REMARKS. 525 
of the curves from all sides towards the centre, by which the areas 
severally comprehended by them become less ; and the lower varia- 
tions, as they successively reach the centre, disappear, and are 
replaced by the closing-in of those of next higher amount. The 
changes which have taken place at all Captain Fitz-Roy’s stations 
comprised within the space referred to, are accordant with the 
systematic alteration thus described. 
Tn all other parts of the hemisphere the lines of variation have 
a progressive westerly movement, and to this also Captain Fitz- 
Roy’s observations correspond. 
It follows, from what has been stated, that the lines on the 
western side of the concentric system in the South Pacific have an 
eastward movement, which presents an apparent anomaly to the 
general progress of the lines of variation in the southern hemis- 
phere, which is from east to west. 
Otaheite, and the Bay of Islands in New Zealand, present exam- 
ples of changes in the variation corresponding to this apparent 
anomaly. The consistency, however, both of the movement and of 
the configuration of the lines of variation in this quarter, with 
those in other parts of the southern hemisphere, and with the 
general system of the magnetic phenomena, has been shewn by 
Mr. Hansteen in the Magnetismus der Erde, and in the Annalen 
der Physik, vol. xxi. 
The annual amount of the change of the variation appears con- 
siderably greater at the Cape of Good Hope and Mauritius than 
at any other of Captain Fitz-Roy’s stations, amounting to about 
eight minutes ; shewing that the variation lines in that quarter are 
changing their position more rapidly than elsewhere. The north 
pole of the needle is moving to the west at the Cape, and to the 
east at Mauritius ; but it will be seen, by areference to the map, 
that these opposite movements are in perfect correspondence 
with the uniform westerly progression of the variation lines, and 
result from their configuration. 
At the stations in the vicinity of the meridian of 65° west, the 
change appears to be very small. 
[The variation at Ascension (13° 30/ W.) is correctly inserted in the 
tables: it is the only one of Captain Fitz-Roy’s stations at which his 
observations are not accordant with those of other observers: the dis- 
cordanee may be occasioned by the great prevalence of local disturbances 
at Ascension. | 
