5>6 DESfTERFlClE CTUNDRI ETCOM SCAL. 



iindricani ■ igitiir fiiporficici p;irs qnaecunque HKMN ac- 

 qualL. elt arcui clliptico NM dudo in latus HN. At 

 vcro , ob vngulas NlCl) ct HFGE fimilcs et acqua- 

 lcs , arca H l^ M N cylindri rcdi fcd clliptici eadcm eft 

 cuH) arca conclpondcntc EtfwD cylindri obliqui ted cir- 

 culuris : vndc patct , ctiam arcam ¥-.emD acqualcm ellc 

 priori fido , ct pcndcrc confcqucntcr ab ellipfcos rc<fli. 

 ficationc. Qiiod mirum clt , cur non dcprchcndcrint acn- 

 ti gcomctrac liipcrioris actatis j cum cx Screni Aiitijjenfis 

 nicdiuitionc i.u.i cognituni diu fit , lcdioncm cyiindri cir- 

 cularis oblitiuam clTiccrc clliplin. 



§.8. Sit nunc limili modo fcmiconus fcalcnusAEI, 

 cuius bafis (cmicircuius AMI , in qua diamctcr AI vtrin- 

 £g. 4. quc prolongata iii B ct D. Sit autcm ni hoc cono trian- 

 giilum pcr axcm AEl talc , vt dcmilTa cx vcrticc coni 

 \l pcrpcndicularis ED in bafin cadat in diamctri pro- 

 longitac pun(fliun D. Capiatur arcus quilibct A M , ct 

 ducatur latus coni M E , cum alio infinitc vicino m E , 

 critque triangulum M //; E cicmcntum liipcrficiei conicac 

 fcalcnac , cuius proindc arcola inuclhg.mda. In M m pro- 

 longatam vtrinquc , doncc diimctro balcos occurrat in B, 

 hoc cft in tangcntcm puncfii M , dcmittatur cx E pcr- 

 pcndiculum EC; crit crgo acrcola quacfita — -^— . Eft 

 autcm ^\ m clcmcntum pcriphcrinc circularis rerpondcnsfc' 

 miapplicatac PM , rcHit crgo indiganda fob EC , pcr- 

 pcndicularis cx E in tangentcm circuli M C. 



§. 9. llacc EC vt commodc dctcrminetur , ducantur 

 rc(fl.ic M D, CD, cum radio baftos MK j dico iam • angulum 

 in bafi iaccntcm MCD cflc rcftum. Nam , quia ED 

 cft pcrpcndicularis ad pkiniMH inferius : cruni suiguU EDM, 



ct 



