V ^ X zz- 





d s- ds' ♦ 



r d y\ _ T .i V d d^. • 



/-» . d T d y -_ T .i V d d^. 



dTds' TtJsddi; 



quac tres formulae coniuncflac, cnm flt dx'-\-dy^-^dz' c ds^, 

 hincque d x d d x -\- d y d dy -^- d z d d z ~Oy ob «'x con- 

 ilans, fient P rt^A: 4- Q^J -^ R ^- ^ <^T. 



§. 10. Euidens autem efl: Iianc formulam Vdx-\- 

 Q//y H- R ^c;, exprimere vim tangentiaJem, qua clemen- 

 tum ds fecundum ipfam diredlionem Zz ^ ternis viribus 

 Vds, Qds^ Kds Ibllicitatur. Quod fi ergo hanc vim 

 tangcntiaiem defignemus pcr © d s, vt Q d s ~P d x ~\^ 

 Q^d y ~\-K d z^ crit vtique dT nz— Q d s, idcoque T =r 

 C—fQds, quemadmodum cx natura rei conftat, quando- 

 quidcm tcnfio femper acquatur fummae omnium virium 

 tangcntialium; fcquc viciffim ex vi tangentiali Qds ct tcn- 

 fiOne T innotefcent ternae vires follicitantes 



?d s — -\-edx-''-4'^-^: 



(lds= ^edy- 

 RJs — -\-etiz- 



Td d y 

 d s' 

 Td dz . 



a t ' 



§. II. Qund fi iam praeter vim tangcntiakm 

 eds etiam vim normaicm in calculum introducere vcli- 

 mus, eamque ponanuis — U d s , cuius direclio non foluni 

 ad clcmentum Zz normalis eft intclligenda , fed ctiam ad 

 planum, in quo duo clemcnta contigua lunt fita, ita vt 

 omnes vires roliicitantes iundim fumtae ad has dnas vires 

 Sds ct n^.f reuocentur: quoniam vis tribus viribus fol" 

 licitantibus ? d s, Q^ds ct Rds acquiualcns cft 

 Aaa Acad,lmp.Sc,lom,VlV.ll, . V dsVi^* 



