Rangarira ndima iri pasi apa uye ipapo pindura mubvunzo gare gare mumutauro mumwe chetewo sechikamu:  Passage: Muenzaniso we deferent-uye-epicycle wakanga washandiswa navazivi venyeredzi vechiGiriki kwamazana amakore pamwe chete nepfungwa ye eccentric (a deferent iyo iri zvishoma kubva pakati pePasi), iyo yakanga yakatokura zvikuru. Mumufananidzo wacho, pakati pechinhu chinokudza hausi Pasi asi nzvimbo yakanyorwa kuti X, ichiita kuti ive yakajeka (kubva muchiGiriki ἐκ ec- zvinoreva kuti "kubva", uye κέντρον kentron zvinoreva kuti "pakati"), uko nzvimbo yacho inotora zita rayo. Nenzira isingafadzi, gadziriro yakanga iripo munguva yaPtolemy yakanga isingawirirani zvikuru nokucherechedza, kunyange zvazvo yakanga yavandudzwa zvikuru kupfuura gadziriro yaHipparchus. Chinonyanya kuoneka ndechokuti kukura kwepuraneti inodzokera shure (kunyanya yeMars) kungava kuduku, uye dzimwe nguva kukuru, kupfuura zvinotarisirwa, zvichikonzera zvikanganiso zvomugariro zvinenge madhigirii 30. Kuti apedze chinetso chacho, Ptolemy akagadzira equant. Equant yaiva nzvimbo iri pedyo nechepakati penzira yepuraneti iyo, kana iwe waizomira ipapo ndokucherechedza, pakati peepicycle yepuraneti nguva dzose yaizoratidzika kufamba nokukurumidza kwakaringana; dzimwe nzvimbo dzose dzaizoona kukurumidza kusingaenzaniswi, kufanana napasi. Nokushandisa equant, Ptolemy akataura kuti aichengeta kufamba kwakanga kwakaenzana uye kwakapoteredza, kunyange zvazvo kwakanga kwakasiyana nepfungwa yaPlato yokufamba kwakapoteredza kwakafanana. Gadziriro yakabva, iyo pakupedzisira yakazogamuchirwa zvikuru kumadokero, inoratidzika kuva isingabatiki kuvanyori venyeredzi vemazuva ano; nyika imwe neimwe yaida epicycle inotenderera pane imwe nzira, inotsiviwa ne equant iyo yakanga yakasiyana nepuraneti imwe neimwe. Yakafanotaura kufamba kwakasiyana-siyana kwomuchadenga, kubatanidza kutanga nokuguma kwokufamba kumashure, kusvika pakukanganisa kukuru kwemadhigirii 10, zviri nani zvikuru kupfuura pasina equant.  Mubvunzo: Ndivanaani vanhu vakashandisa deferent uye epicycle muenzaniso?
Vazivi venyeredzi vechiGiriki