-30 Mr, Land en's Invcjligatio?! of 





S 3^^ st ' 3^-^^ 



. C^/3>'.^+:f^.e/3y; 



S being — v/D'/zT/z' — BC^/^. 

 And, no external force being luppofed to a<5l on the body, it fol- 

 lows, that the fum of thefe three forces mufl be = o: there- 

 fore we may infer, that 



T will ber= - X n23^i-^^r--fi2 2 ; wnich agree* 



ing with the value of T found above,, the truth of our pre- 

 ceding procefs is. thus confirmed. 



M 



The force ~^- X By r 4- D /3T + e/3y , arifing, from thofe. 



three forces, is the whok ^owVi centrifugal force of the particles, 

 of the revolving body, to turn it about the diameter NAN the 

 way it. will adually be urged to turn by fuch force; the value 



whereof fo computed will be {^~-^%s/Wnfn'--'SiQa'y — 



-—y) ^qual to the value of the force F computed above, both 



being confidered as urging the body to turn m the fame 

 diredion. And the quantity 



Ue 



q«3sT 



-x^' + r . y^(^-d' -\-b'- . D/55>. + r + ^^ . C(^y^ 



( = -^ Xthe fum of all the w'YifJis the value of the motive 



force which, ading in that very direction , is requifite to caufe 

 the momentary pole to change its place as abov^e defcribed. 

 Thus we fee diftindly how the equation arifes, by which the 



value of T is jufl now determined. I do 



