28 MEM O IR S of the 
tho' it be certain, according to the general effedl, the difference 
ought to be the contrary way j notwithftanding which, the vari- 
ations in both places do change alike: Hence and from fome 
other of the like nature, Mr. Halky concludes, that the two poles 
of the external globe are fixed in the earth, and that if the needle 
were wholly governed by them, the variations thereof would be 
always the fame with fome little irregularities on the account juft 
now mentioned 5 but the internal fphere, having luch a gradual 
tranflation of its poles, does influence the needle, and direct it 
varioufly, according to the refult of the attra61:ive or direftive 
power of each pole 5 and confequently there muft be a period of 
the revolution of this internal ball, after which the variation will 
return again as before 5 but if it Ihall in future ages be obferved 
otherwiie, we muft then conclude, that there are more of thele 
internal Ipheres, and more magnetical poles than four, which at 
prefent we have not a lufficient number of oblervations to deter- 
mine, and particularly in that vaft Mare del Zu/% which occupievS 
ib great a part of the whole furface of the earth : If then two of 
the poles be fixed, and two moveable, it remains to afcertain, 
which they are that keep their place, and Mr. Halky thinks we 
may lafely determine that our European north pole, fuppofed to 
be near the meridian of the Land's End^ and about 7*^ there- 
from, is that of the two northern poles which is moveable, and 
which hath chiefly influenced the variations in thefe parts of the 
world 'y for in Hudfon'sHay, which is under the diredion of the 
American pole, the change is not obferved to be near lb faft as in 
theie parts of Europe^ tho' that pole be much farther removed 
from the axis 5 from the like obfervation of the flow decreafe of 
the variation on the coaft of Java and near the meridian of the 
' AJian pole, this latter, of the two Ibuth poles, is fixed, and 
conlecjuently, the American moveable : If this be allowed, it is 
plain, that the fixt poks are the poles of this external fhell or 
Cortex of the earth, and the other two the poles of a magnetical 
ITuckiiS included and moveable wirhin the other 5 it likewile 
follows, that this motion is to the weft, and confequently 
that the aforefaid Nucleus has not precifely attained the 
fame degree of velocity with the exterior parts in their di- 
urnal revolution, but lo very nearly equals it, that in 5^5 re- 
volutions the difference is fcarcely Icnfible j this is conceived to 
ariie from the impullc, whereby this diurnal motion was imprefled 
on the earth, bcmg given to the external parts, and from thence 
in time communicated to the internal , but not fo, as perfectly to 
equal the velocity of the firft motion imprefled on, and ftill con- 
ferved 
