c sn ) 
South America, and which at prcfent is higheft about 
the Mouth of Riode la Plata, it has been obferved that 
in the Eaftern parts thereof, the Variation of the Needle 
gradually decreafes 5 but whether on the contrary it in- 
creafes in thofe places which lie more Wefterly than 
that traft wherein the higheft Baft Variation is found 3 
or how it may be in the vaft Pacifc^StB 9 we have not 
experience enough to afcertain, only we may by Analo- 
gy infer, that both the Eaft and Weft Variations therein 
do gradually increafe and decreafe after the fame Rule. 
Thefe Phenomena being well underftood and duly 
confidered do fufficiently evince, That the whole mag- 
netical Syftem is by one or perhaps more Motions tran- 
dated, whether Eaftwards or Weftwards I (hall anon 
difcufs ; that this moving thing is very great, as extend- 
ing its effe&s from Pole to Pole 5 and that the Motion 
thereof is not per faltum , but a gradual and regular 
Motion. 
Now confidering the ftru&ure of our Terraqueous 
Globe, it cannot be well fuppofed that a very great 
part thereof can move within it, without notably chan- 
ging its Centre of Gravity and tbeEquilibre of its parts, 
which would produce very wonderful Effefts in chan- 
ging the Axis of Diurnal Rotation, andoccafion ftrange 
alteration in the Sea's Surface, by Inundation* arid Rfc- 
cefles thereof, fuch as Hiftory never yet mentioned* 
Befides, the {olid parts of the Earth are not to be gran- 
ted permeable by any other than fluid Subftanccs, of 
which we know none that are any ways Magnetical. So* 
that the only way to render this Motion intelligible and 
poffible, is,to fuppofeit to turn about the Centre of the 
Globe, having its Ctntreof Gtavity fixt and immove- 
able in the fame common Centre of the Earth : And 
there is yet required that this moving internal Subftance 
be lobfe and detached from the externa! parts of the 
Earth, whereon we live 5 for otherwife were it afford* 
thereto, 
