▁certain ▁parts ▁of ▁the ▁Earth . ▁ ▁H ellen istic ▁Mediter rane an ▁A ▁vital ▁contribution ▁to ▁mapping ▁the ▁reality ▁of ▁the ▁world ▁came ▁with ▁a ▁scientific ▁estimate ▁of ▁the ▁circum ference ▁of ▁the ▁earth . ▁This ▁event ▁has ▁been ▁described ▁as ▁the ▁first ▁scientific ▁attempt ▁to ▁give ▁ge ographical ▁studies ▁a ▁mathematical ▁basis . ▁The ▁man ▁cred ited ▁for ▁this ▁achiev ement ▁was ▁Er at ost hen es ▁( 2 7 5 – 1 9 5 ▁BC ), ▁a ▁Greek ▁scholar ▁who ▁lived ▁in ▁H ellen istic ▁North ▁Africa . ▁As ▁described ▁by ▁George ▁S art on , ▁historian ▁of ▁science , ▁" there ▁was ▁among ▁them ▁[ Er at ost hen es ' s ▁contempor aries ] ▁a ▁man ▁of ▁genius ▁but ▁as ▁he ▁was ▁working ▁in ▁a ▁new ▁field ▁they ▁were ▁too ▁stupid ▁to ▁recognize ▁him ". ▁His ▁work , ▁including ▁On ▁the ▁Me asure ment ▁of ▁the ▁Earth ▁and ▁Ge ograph ica , ▁has ▁only ▁surv ived ▁in ▁the ▁writ ings ▁of ▁later ▁philosoph ers ▁such ▁as ▁Cle om edes ▁and ▁Stra bo . ▁He ▁was ▁a ▁devoted ▁ge ograph er ▁who ▁set ▁out ▁to ▁reform ▁and ▁perfect ▁the ▁map ▁of ▁the ▁world . ▁Er at ost hen es ▁argued ▁that ▁accurate ▁mapping , ▁even ▁if ▁in ▁two ▁dimensions ▁only , ▁depends ▁upon ▁the ▁establishment ▁of ▁accurate ▁linear ▁measurements . ▁He ▁was ▁the ▁first ▁to ▁calculate ▁the ▁Earth ' s ▁circum ference ▁( with in ▁ 0 . 5 ▁percent ▁accuracy ). ▁His ▁great ▁achiev ement ▁in ▁the ▁field