= (130 == 



gulis, qui diflfcrcntiam longiciidiiiis corum iii Splmer.i dctermi- 

 nant. Practcrca quilibct 1'arallchis M N cll ctiam in Spliac- 

 roide elliptica circuius , ct quidcm iiio calu , qucm hic co.ifi- 

 dcramus , eft bafis coni rcifii , cuius ^ertex in O , undc cius- 

 dcm proicclio lcu intcrlcfiio iiuius coni cum plano tabnlae AB 

 bafi parallclo paritcr cnt circulus radio C /;; circa ccntrum C 

 dcfcriptus. 



ITacc ii^itur omnia luicusquc cum proic(flionc fpbacrica 

 conucniunt, cxccpto radio C w, qui luc alicr detcrminatur ac 

 in proicdionc Ipliacrica. Quam quidcm ditfcrcntiam facilc pa- 

 tct dupliccm habcrc fontcm: non (olum cnim dillantia oculi a 

 tabula C)C dirtcrt a radio Sphacrac C A , vcrum latiiudo qno- 

 que loci M hic non dctcrminatur pcr lincam M C lcd M D , 

 quac tangcnti T t normalitcr inlillit. 



§, 3. Contemplemur igitur ellipfin APMB, atque 

 pofitis fcmiaxc maiorc C A zr <7 , minorc C P zz: ^ , abfcilih 

 C N =: .V , ordinata NM fcu radio Paralieli —y^ habcbimus 

 e natura clliplcoj): yy — °^^^{b b — x x); \cl pofitp ^alorc 

 fra(ftionis -J- = ;// , yy — aa — mm x x , ct .v x — —^J^ . 

 Ratio Ncutoniana, qua hic fcmpcr vtar, cf\ a : Z» — 230 : 22p, 

 \ndc fit ///znij^^iz: 1,00436651 2:3- 



Du^fia iam in plano APB rcda /T cllipfin tangcntc 

 in M , ct M D cidcm normali , crit P D M dillantia poli a 

 vcrticc V, idcoquc , fi latitudo loci M obfcruata dicatur (3, 

 crit IM) M :r= 90° — (i. Quo nunc acquationcm intcr radium 

 C ;;; ct latitudincm p nnncifcamur , .v ct r pcr (3 funt cxpri- 

 mcudac. Qucm in fincm notciur, fubnormalcm 



N D — — 2L'— > — ;;; ;;; x — /// V {o a — yy) , 



ob 



