324 Mr. Barlow on the temporary magnetic effect 
being resolved into two, the one parallel to the original 
axis, and the other perpendicular to it, and the former being 
nearly neutralized by the magnets used for the purpose 
in the first instance, the perpendicular forces will act upon 
the needle in the same manner as if the ball were really 
polarized in the direction above alluded to. 
Having got this view of the subject, I soon found that 
many of my former results, which appeared to have scarcely 
any conformity among themselves, were perfectly consist- 
ent with this hypothesis : of these the experiments given 
above, before the needle was neutralized, may be mentioned. 
In these I found the point of change to be at about 30° on 
each side of the axis, so that the arcs in which similar effects 
were produced were divided into the unequal portions of 60°, 
120°, 60®, and 120°, which appeared to be anomalous; but 
according to the view now taken of the subject, this is per- 
fectly consistent ; it is precisely what ought to happen ac- 
cording to the law tan. dip. = 2 tan. mag. lat. and which 
actually takes place on the'" earth'. That is in passing from 
the magnetic equator 30° towards the pole, the dipping needle 
has actually described a quadrant, as referred to its position 
at the equator ; and it would describe a quadrant, in an oppo- 
site direction in going 30° towards the other pole ; so that in 
passing through 60° the needle is actually inverted ; but if 
we start from mag. lat. 30° through the pole, we must pass 
through an arc ^ of' 120° before the direction of the needle is 
inverted, and the same in the other half of the meridian ; and 
in like manner by referring the motion of my needle as in- 
duced by the rotation of the shell to its original magnetic 
direction, it is obvious that I ought to have found, as I actually 
