spS P R I N C I P 1 A 



pro ftatu preflionis p haec habebitur aequatio 



dpz-z-dz~2u(Ldx-t-Mdy-\-Ndz)—-dz -2 udu-2vdv--2wdw 

 -2v{M.dx-\-mdy-\-ndz) -2%dx-2^fldy-2^fldz 



-2w f Ndx -\-ndy-\-vdz) 

 - 2-Qdx— 2 ^fldy— 2 ffcdz 



62. Qnia vero eft £ — jy\. $fl zzzjj; 9l = ir; 

 erit integraodo u 



p—C—z—uu—vv—ww-2f{ d -f. dx-r-j}.dy-\- ffk */£) 

 Cum autem per conditionem inuentam fit udx-\-vdy 

 -\-wdz integrabile, ponatur eius integrale =rS, quod, 

 quoniam etiam tempus t inuoluere poteft , fit fumto 

 quoque f variabili : 



d S zzzudx -\- v</y-f- w ■</« -4- U d^ 



ju cfU d-u dU dw dU ^ 



■ entqie aT = ,-; w ~ ^; aT — ^ • Quare cum 

 fit in genere fumto tempore t conftante , vti id qui- 

 dem in fuperiori integrali artiimitur, 



dU j A . dXJ j , dV , j TJ 



d~ x dx-^-j^.dy-i-^.dz — dU 

 habebimus : 



pzzzC — z — uu — vv — ww—zU, fiue 



■ pZZ.C — Z — UU — VV-WW — 2.jj 



63 . Perfpicuum hic eft , u u -\- vv -\- w w expri- 

 rnere quadratum verae pundti X celeritatis ita , vt, fi ce- 

 leritas huius pundi vera dicatur ~V> habeatur pro 

 preffione ifta aequatio: 



p=C-z-NV~^-. 



ad quam ergo inueniendam, primum formulae udx-\-vdy 

 -\-wdZ) quam completam effe oportet , quaeratur in~ 

 tegrale S, hocque denuo differentietur, pofito folo tem- 



pore 



