Mifiellanea Curiofa. 5 i 



moveable within the other. It likewife follows, 

 that this Motion is Weft wards, and by come- 

 quence that the aforefaid Nucleus has not precife- 

 ly attained the fame degree of Velocity wirh the 

 exterlour Parts in their diurnal Revolution ; but 

 fovery nearly equals ir, that in 365* Revolves the 

 the difference is fcarce (enfible. This I conceive' 

 to arife from the Impute whereby this diurnal 

 Motion was impreft on the Earth, being given to 

 the External Parts, and from thence in time com- 

 municated to the Internal ; but not (b as perfect- 

 ly to equal the Velocity of the firft Motion im- 

 prefs'd on, and ftill conferv'd by the fuperficial 

 Parts of the Globe. 



As to the quantity of this Motion it is al- 

 moft impoifible to define it, both from the Na- 

 ture of this kind of Obfervation, which can- 

 not be very accurately perform'd, as alfo from 

 the Imall time thefe Variations have been ob- 

 ferv'd, and their Change difcover'd. It appears 

 by all Circumftances, that its Period is of ma- 

 ny Centuries of Years, and as far as may be col- 

 lected from the Change of the Place, where 

 there was no Variation, by reafon of the Equi- 

 libre of the two Southern Magnetical Poles, vi%< 

 from Cape d y Agulhas to the Meridian of St. Hele- 

 na (which is about 23 degr. in about ninety Years) 

 and of the place where the Wefterly Variation 

 is in its ttKfjul or greateft Deflection, being a- 

 bout half fo much, vi%. from the Ifle of Diego 

 Hpi% to the South Weft Parts of Madagascar '. ! 

 We may with fome Reafon conjecture, that the 

 American Pole has mov'd Weftwards forty fix 

 Degrees in that time, and that the whole Period 

 thereof is perform'd in (even hundred Years, or 

 thereabouts ; fo that the nice Determination 

 of this, and of feveral other Particulars in the 

 E % Magnetick 



