Sit ABLGlobus, Ccentrum ejus, BPVRota ei inſiſtens, E
centrum Rotæ, Bpunctum contactus, & Ppunctum datum in pe
rimetro Rotæ. Concipe hanc Rotam pergere in circulo maximo
ABLab Aper Bverſus L,& inter eundum ita revolvi ut ar
cus AB, PBſibi invicem ſemper æquentur, atque punctum illud
Pin perimetro Rotæ datum interea deſcribere Viam curvilineam
AP.Sit autem APVia tota curvilinea deſcripta ex quo Rota
Globum tetigit in A,& erit Viæ hujus longitudo APad duplum
97[Figure 97]
ſinum verſum arcus 1/2 PB,ut 2 CEad CB.Nam recta CE(ſi
opus eſt producta) occurrat Rotæ in V,junganturque CP, BP,
EP, VP,& in CPproductam demittatur normalis VF.Tan
gant PH, VHCirculum in P& Vconcurrentes in H,ſecetque
PHipſam VFin G,& ad VPdemittantur normales GI, HK.
centrum Rotæ, Bpunctum contactus, & Ppunctum datum in pe
rimetro Rotæ. Concipe hanc Rotam pergere in circulo maximo
ABLab Aper Bverſus L,& inter eundum ita revolvi ut ar
cus AB, PBſibi invicem ſemper æquentur, atque punctum illud
Pin perimetro Rotæ datum interea deſcribere Viam curvilineam
AP.Sit autem APVia tota curvilinea deſcripta ex quo Rota
Globum tetigit in A,& erit Viæ hujus longitudo APad duplum
97[Figure 97]ſinum verſum arcus 1/2 PB,ut 2 CEad CB.Nam recta CE(ſi
opus eſt producta) occurrat Rotæ in V,junganturque CP, BP,
EP, VP,& in CPproductam demittatur normalis VF.Tan
gant PH, VHCirculum in P& Vconcurrentes in H,ſecetque
PHipſam VFin G,& ad VPdemittantur normales GI, HK.