*.] THEORY OF APPROXIMATION. 467 



perfect vacuum, where~the^i s no 



, me um 



kind ; the force of gravity must be unffonn and actS 

 parallel lines; or else the moving body must be either a 

 mere point, or a perfect centrobaric body, that is a bod v 

 possessing a definite centre of gravity. These condition. 

 cannot be really fulfilled in practice. 7 The next ea ?ep 

 m the problem was made by Newton and HuySens the 

 latter of whom asserted that the atmosphere would offer a 

 resistance proportional to the velocity of the m ng body 

 and concluded that the path would have in consequence 

 a logarithmic character. Newton investigated in TS* 

 manner the subject of resisting media, and came to the 

 conclusion that the resistance is more nearly ^portiona! 



theoretical and experimental investigation has been spent 



and final 



oS^t^r 



Nw u rt "etvaon 



aewtoa thought that the mutual disturbances of tho 



ana featurn, near their conjunction 2 The exnan^inr. nf 



emrae 

 D6mg P ssesse d of temperature apart from 



i m ? e ^^ effect8 ' E " mford ' ^ ^ ^s 

 leading to a determination of the mechanical 



Prop. 



H H 2 



