▁of ▁a rias ▁reduced . ▁One ▁of ▁the ▁most ▁striking ▁add itions ▁was ▁the ▁ch orus ▁at ▁the ▁end ▁of ▁Act ▁III ▁of ▁Mo ï se , ▁with ▁a ▁cres c endo ▁repet ition ▁of ▁a ▁di at onic ▁asc ending ▁bass ▁line , ▁rising ▁first ▁by ▁a ▁minor ▁third , ▁then ▁by ▁a ▁major ▁third , ▁at ▁each ▁appearance , ▁and ▁a ▁desc ending ▁chrom atic ▁top ▁line , ▁which ▁r oused ▁the ▁excitement ▁of ▁aud ien ces . ▁ ▁Ross ini ' s ▁government ▁contract ▁required ▁him ▁to ▁create ▁at ▁least ▁one ▁new ▁" grand ▁op ė ra ", ▁and ▁Ross ini ▁settled ▁on ▁the ▁story ▁of ▁William ▁Tell , ▁working ▁closely ▁with ▁the ▁libre tt ist ▁Ét ienne ▁de ▁J ou y . ▁The ▁story ▁in ▁particular ▁enabled ▁him ▁to ▁indul ge ▁" an ▁underlying ▁interest ▁in ▁the ▁related ▁gen res ▁of ▁folk ▁music , ▁past oral ▁and ▁the ▁pictures que ". ▁This ▁becomes ▁clear ▁from ▁the ▁over t ure , ▁which ▁is ▁explicitly ▁program m atic ▁in ▁describing ▁weather , ▁scen ery ▁and ▁action , ▁and ▁presents ▁a ▁version ▁of ▁the ▁r anz ▁des ▁v aches , ▁the ▁Swiss ▁cow h erd ' s ▁call , ▁which ▁" under go es ▁a ▁number ▁of ▁transformations ▁during ▁the ▁opera " ▁and ▁gives ▁it ▁in ▁Richard ▁Os bor ne ' s ▁opinion ▁" something ▁of ▁the ▁character ▁of ▁a ▁le it mot if ". ▁In ▁the ▁opinion ▁of ▁the ▁music ▁historian ▁Benjamin ▁Wal ton , ▁Ross ini ▁" s atur ate