OUTLINES OF NATURAL PHILOSOPHY. 



300. Hence the fraction which expresses the 

 ellipticity of the meridian, or the excess of the 

 equatorial above the polar radius, is to that 

 which expresses the ratio of the centrifugal 

 force at the equator, to gravity at the same 

 place, as 5 to 4. 



This is also demonstrated by MACLAURIN, and fol- 

 lows readily, from comparing the last theorem with 

 those already stated concerning the attraction of 

 spheroids. 



301. The centrifugal force is to the gravity 

 at the equator, nearly as 1 to 289. 



A body under the equator falls in a second through 

 15.0515 French feet, as is concluded from the 

 length of the pendulum vibrating seconds. 



Now the centrifugal force is measured by the de- 

 flection of a body from the tangent produced by 

 the Earth's rotation in 1 second. But a point of 

 the equator in a second of mean solar time, de- 

 scribes an arch of 15".04*17 of a degree ; the 

 versed sine of which, multiplied into the radius 

 of the equator, in French feet, gives the deflec- 



tion, which is found to be of the direct de- 



scent. 



302. A 



