284 Mathematical Elements Book IV.

of the Earth the Elevation of the Moon is of76,8 Feet; and if the Moon be homogeneous,

1433 there will mt be an/Equilibrium, unless the Axis ofthe Spheroid exceeds the Diameter , which is perpen-dicular to it, 153,60 Feet.

1434 The Elevation of the Moon from the Action of theEarth , may be difcover’d by one single Propor-tion, by knowing the Elevation of the Sea fromthe Moon’s Action ; for these Elevations are in aduplicate inverse Ratio of the Gravities on the Sur -faces of those Bodies.

1435 If, supposing this to be the Figure of the Moon,we conceive the Parts to cohere, there will not bean y Equilibrium between the Parts of the Moon, un-less the Axis of the Spheroid be directed towardsthe Earth ; whence we fee the reason why theMoon always turns the fame Face towards the Earth,by which continual Agitation the Moon has at

1436 least acquired the Motion about its Axis, of which

* 970 we have before spoken* ; which Motion mufi ne ‘

10 9 2 ceffarily be perform'd in the fame ’Time as the Moon

performs one Revolution , for from the Action a-bove-mention’d it must necessarily adapt itsedto such a Celerity ; for if the Celerity was grea-ter , it would be continually retarded by theForce whereby the fame Face is always direct-ed towards the Earth; and if this Celerity wasless, it would be continually accelerated ; yetthis Force is not great enough sensibly to di-sturb the Æquibility of the Motion acquired

1437 About the Axis every Revolution ; thereforethe Motion about the Axis is equable, though theMoon be moved in its Orbit by an unequal Mop

* 966 twn*. The Position also of the Moon’s Axis

cannot be so chang’d by the Force above-men-

tion’ds