118 Professor Hansteen’s ^ 
of convergence B and A, and to the weaker h and a* Nor, oh 
the other hand, are those circumstances very decidedly favour- 
able to such a supposition. It receives confirmation, however, 
from several facts connected with the variation ; many older ob- 
servations in the southern hemisphere are plausibly accounted 
for; and the earliest vicissitudes of that phenomenon, observed in 
Europe, correspond with the system rather strikingly. Ac- 
cording to the principles already stated, the stronger north point 
B, must have lain, two centuries ago, about Behring’s Strait, 
considerably to the westward of its present position. 
Before 1600, the north point h must have lain still farther to 
the westward of its present position, as far probably as the east 
coast of Greenland ; for which reason, it seems likely that the 
easterly system of variations, which extended over Europe in 
1600, lay previously more to the west. And this supposed 
change in the variation, brought about by the motion of that 
magnetic point, appears to be confirmed by several facts. The 
easterly variation at Paris seems to have reached its maximum 
in 1580; for in 1541, it is stated as 'T or 8°; in 1550, Oron- 
tius Finnaus found it between 8° and 9°; in 1580, it was 11° 
80'; and finally, in 1608, it was 8° 45'; since which time it has 
continually diminished. Hence it is probable, that about ^the 
middle of the fifteenth century, the variation in Paris was 0°, 
and westerly before that period: in 1450, the north-east por- 
tion (which passes through Irkutsk in the present chart) of the 
line without variation passed over Paris ; after which, the varia- 
tion became easterly, attained its maximum in 1580, and finally 
vanished, because the north-west portion (near Casan in the pre- 
sent chart) of the same line went over Paris in 1666. As the 
north point h moved eastwards, the whole easterly system of va- 
riations in Europe followed it, and is now to be found in Sibe- 
ria : the north point B also approached Europe slowly, and oc- 
casioned an augmenting westerly variation, which, however, for 
the same reason, will subsequently diminish. In jthe United 
States of America, the westerly variation must needs decrease, 
for the point B is mthdrawing; and before another half century,^ 
the variation, for a like reason, will become westerly.” 
From the secular inequalities of the magnet, Mr Hansteen 
turns to its daily and hourly inequalities ; and the last chapter 
