ric elli ▁in ▁particular ▁was ▁instrument al ▁in ▁ref ining ▁and ▁prom oting ▁the ▁method ▁of ▁ind iv is ibles . ▁He ▁also ▁benef ited ▁from ▁the ▁patron age ▁of ▁Ces are ▁Mars ili . ▁ ▁Tow ards ▁the ▁end ▁of ▁his ▁life , ▁his ▁health ▁decl ined ▁significantly . ▁Ar th rit is ▁prevent ed ▁him ▁from ▁writing , ▁and ▁much ▁of ▁his ▁correspond ence ▁was ▁dict ated ▁and ▁written ▁by ▁Steph ano ▁degli ▁Ang eli , ▁a ▁fellow ▁Jes u at ▁and ▁student ▁of ▁Caval ieri . ▁Ang eli ▁would ▁go ▁on ▁to ▁further ▁develop ▁Caval ieri ' s ▁method . ▁▁ ▁In ▁ 1 6 4 7 ▁he ▁died , ▁probably ▁of ▁g out . ▁ ▁Work ▁ ▁From ▁ 1 6 3 2 ▁to ▁ 1 6 4 6 , ▁Caval ieri ▁published ▁eleven ▁books ▁dealing ▁with ▁problems ▁in ▁astronom y , ▁opt ics , ▁motion ▁and ▁geometry . ▁ ▁Work ▁in ▁Opt ics ▁ ▁Caval ieri ' s ▁first ▁book , ▁first ▁published ▁in ▁ 1 6 3 2 ▁and ▁repr int ed ▁once ▁in ▁ 1 6 5 0 , ▁was ▁Lo ▁Spec chio ▁U st orio , ▁over o , ▁Tr att ato ▁delle ▁sett ioni ▁con iche , ▁or ▁The ▁Burn ing ▁Mir ror , ▁or ▁a ▁Tre at ise ▁on ▁Con ic ▁Se ctions . ▁ ▁The ▁aim ▁of ▁Lo ▁Spec chio ▁U st orio ▁was ▁to ▁address ▁the ▁question ▁of ▁how ▁Arch im edes ▁could ▁have ▁used ▁mirror s ▁to ▁burn ▁the ▁Roman