▁to ▁Rio , ▁res cu ed ▁C out inho ▁and ▁Cab ral ; ▁they ▁completed ▁their ▁journey ▁with ▁a ▁new ▁aircraft . ▁A ▁comm emor ative ▁painting ▁of ▁the ▁rescue ▁was ▁made ▁by ▁the ▁Portuguese ▁painter ▁and ▁cart oon ist ▁José ▁Stuart ▁Car val h ais . ▁ ▁In vent ions ▁G ago ▁C out inho ▁invent ed ▁a ▁type ▁of ▁se xt ant ▁incorpor ating ▁two ▁spirit ▁levels ▁to ▁provide ▁an ▁artificial ▁horizon . ▁This ▁adaptation ▁of ▁the ▁traditional ▁marine ▁se xt ant ▁allowed ▁navigation ▁without ▁visual ▁reference ▁to ▁the ▁real ▁horizon . ▁He ▁also ▁invent ed ▁an ▁optical ▁flight ▁instrument , ▁to ▁be ▁mounted ▁on ▁the ▁plane ' s ▁co ck pit ▁floor , ▁which ▁measures ▁le ew ay ▁in ▁flight ▁whenever ▁ground ▁remains ▁visible . ▁ ▁Histor ian ▁work ▁He ▁dedicated ▁himself ▁to ▁the ▁na ut ical ▁history ▁of ▁the ▁Portuguese ▁Disc over ies ▁after ▁ 1 9 2 4 . ▁His ▁vast ▁body ▁of ▁work ▁later ▁would ▁be ▁published ▁in ▁A ▁N á ut ica ▁dos ▁Des c ob r iment os ▁( The ▁N aut ical ▁of ▁the ▁Disc over ies ) ▁( 1 9 5 1 – 1 9 5 2 ), ▁in ▁two ▁volumes . ▁ ▁Gallery ▁ ▁References ▁ ▁Bibli ography ▁P into , ▁R ui ▁Miguel ▁da ▁Costa ," G ago ▁C out inho ▁sim ples ▁a vent ure iro ▁ou ▁um ▁hom em ▁de ▁Ci ência ", ▁in ▁Fil atel ia ▁L us it ana , ▁série ▁III , ▁n º 1 9