▁led ▁first ▁to ▁the ▁discovery ▁of ▁Porto ▁Santo ▁Island ▁( near ▁Made ira ) ▁in ▁ 1 4 1 8 , ▁redis cover y ▁of ▁the ▁Az ores ▁in ▁ 1 4 2 7 , ▁the ▁discovery ▁of ▁the ▁Cape ▁Ver de ▁Islands ▁in ▁ 1 4 4 7 ▁and ▁Sierra ▁Le one ▁in ▁ 1 4 6 2 . ▁ ▁Com b ined ▁with ▁the ▁empir ical ▁observations ▁gathered ▁in ▁ocean ic ▁se af aring , ▁mapping ▁wind s ▁and ▁curr ents , ▁Portuguese ▁expl or ers ▁took ▁the ▁lead ▁in ▁the ▁long ▁distance ▁ocean ic ▁navigation , ▁opening ▁later , ▁at ▁the ▁beginning ▁of ▁the ▁ 1 6 th ▁century , ▁a ▁network ▁of ▁ocean ▁routes ▁covering ▁the ▁Atlantic , ▁the ▁Indian ▁and ▁the ▁western ▁Pacific ▁o ce ans , ▁from ▁the ▁North ▁Atlantic ▁and ▁South ▁America , ▁to ▁Japan ▁and ▁S out heast ▁Asia . ▁ ▁The ▁Portuguese ▁discovered ▁the ▁two ▁large ▁volta ▁do ▁mar ▁( mean ing ▁literally ▁turn ▁of ▁the ▁sea ▁but ▁also ▁return ▁from ▁the ▁sea ) ▁curr ents ▁and ▁trade ▁wind s ▁of ▁North ▁and ▁of ▁South ▁Atlantic ▁ocean ▁( appro xim ately ▁in ▁the ▁first ▁half ▁and ▁in ▁the ▁late ▁ 1 5 th ▁century ▁respectively ), ▁that ▁p aved ▁the ▁way ▁to ▁reach ▁the ▁New ▁World ▁and ▁return ▁to ▁Europe , ▁as ▁well ▁as ▁to ▁circ umn avig ate ▁Africa ▁in ▁western ▁open ▁sea , ▁in ▁future ▁voy ages ▁of ▁discovery , ▁avoid ing ▁contrary ▁wind s ▁and ▁curr ents . ▁ ▁King ▁John