( 10 ! ) 
centrifugal Force at the Equator to the mean Force 
of Gravity (by Corol . 2. Trop. 4. 1. Trincip .) 
were it not for the Adion of the Sun on the Moon. 
Therefore (by Cor ok 1 7. Trop. 66. Lib. 1, Trinctp.) 
I fay, as the Square of the Syde^ealYear, to the Square 
of the periodickTime of the Moon, that is, as 179 
to Unity, fo is 287.7 t0 16 5 which being added 
ro 287.7, makes 2,89.3. And therefore, as Unity 
to 289, negleding the Fradion which is uncertain ; 
fo is the centrifugal Force at the Equator to the 
mean Force of Gravity on the Surface. And thence 
(by Article 4.) as 289 to^, fo is the mean Diameter 
to the Difference of the longefl and fhorteft : And 
therefore, as the Axis is to the equatoreal Diameter, 
fo is 2307 to 2317, or in fmaller Numbers, as 231 
to 232, the fame as Sir Ifaac Newton found in a 
different manner ; for he makes it as 230 to 231, 
and as 230 to 231, fb is 231 to 232. 004. 
6. In the fame manner the Proportion of the 
Diameters of any Planet may be found, if it has a 
Satellite : For Inftance, in Jtipiter , he turns about 
his Axis in 9 h , 56', or in 596 Minutes : And his 
third Satellite revolves about him in 7 d , 3 h , 42', 
36", or in 10302.6 Minutes, at the diftance of 
15.14X of his Semidiameters. Therefore, I fay, as 
the Cube of 1 7.1 41 to Unity, fo is the Square of 
10302.6 to 30579, the Square of the Number of 
Minutes in which a Satellite would revolve about 
him at the diftance of his Semidiameter : And as 
this laft: Number is to 355216, the Square of 59 6, 
fo is Unity to ni, or the centrifugal Force at his 
Equator to the mean Force of Gravity on his Sur- 
face. There is no need of correcting this Number, 
as 
