= (i25) = 



de figiira nc rufcipi qiiidcm pof^ct , nccefTc cft vt formula 

 hacc iniicnta intcgrationcm admittat , quod quidcm in primo 

 tcrmino ''- '^ Ipoutc cucnit; tum vcro ctiam inrcgratio in (c- 

 cundo tcrmino fcmper fucccdit , dummodo Z fucrit fun(f(io 

 ipfius z vti afrumfimus ; quair.obrcm fupcrclt vt portrcmum 

 mcmbrum L(xdx — xdj) intcgrationcm admittat , quod 

 ciim hoc niodo repracfcntari pofht ^JLl (^^ — ^-J'), intcgratio 

 locnm habere ncquit, nifi *4^ fit fundio ipfius |-, ideoquc 

 functio nullius dimci^fionis ipfarum x ct y ; quarc cum z — 

 V(x X -hjj) vnam habcat dimcnfioncm, ncccnc cft vt S fit 

 fiin<flio homogcnca ipfarum a* ct j, cuius dimcnfionum nume- 

 rus fit — I, vndc iam fatis clarc cognofcimus indolcm funtfcio- 

 nis S, fiquidem pro ccrto aflumamus, fiiiuram tcrrac acquili- 

 bfio clfc pracditam. 



5. 7. Quo hoc clarius appareat, loco coordinatarum 

 of et r iu poftrcmo membro introducamus anguhim ACZrCp, 

 eritquc x ~ z cof. CP ct r — z fin. Cj), vnde fit j d x — x dj :z 

 — zzdi^^ ita vt iam nortra acquaio hanc induat formam: 



quac manifcrto intcgrationcm non admittit, nifi fucrit Sz fun- 

 (ftio anguli Cj). Sit igitur O il\a fundio, critquc vis hitcralis 

 S ~*i vbi patct, iltam funcflionem cD ita dcbcrc cire com- 

 paratam , vt enancfcat tam pofito (|) rz o , quam (J) rz 90**. 

 Hinc igitur integrando adipifccmur 



/^ zz c -+- ^p -/z ;j 2 -/o ci cp. 



Atquc hic porro obfcruandum eft acquilibrium fubfiftcrc non 

 poffc, nifi ctiain formula/*^ fit intcgrabilis.. Quoniam autcm 



hic dcnfitatcm nqnac q vbique conltantcm afTumcre licct, crit 



Q 3 vtique 



