Del Cav. Gioegini 91 ■ 



da=b§r'— cèq òb=cèp' — adr' Oc =aÒq—bdp , 



(, 8) { da'=b'dr' —cdq ...M ^cdp -adr de =adq' — b'dp', 



da"—b"dr—c"dq'. . . M"=c"àp'—a"dr' dc"=:a"dq'^b"dp' : 



r dadp -i- db dq' -i- de dr = o , 

 (19) . . . ; da'dp'-i-db'dq'-^de'd/ = o, ' 

 (^ da"dp'-i-db"dq'-+-de"dr=o, 



§a'-^ da'^-h da"'= dq'^-i- dr\ 

 (ao) . . . ldb'-t-db'''i-db"'=dr''-hdp'\ 



de^-^de''-^dc"'=dp'-i-dq'\ " '" '■ ' 



/ ' . ■" . ■ . ■ ' ' ' - 



Siccome poi (12) 



■^-y-- dp = a"da'-hb"db'-hc"de', ' '■ 



che inoltre (lO) • / 



da= b'dr- c'dq'....db'=c'dp'—a'dr'....dc'=adq'—b'dp'y 

 avremo 



dp = {eh"— c"b)dp'-+- {e' a— a"c')dq'-h {ab— b"a')dr;. 

 e poiché (5) 



a =^ a e — be . . . . = e a— e a . . . . e = a b — aO ; 



sarà 



dp = adp'-^bdq'-+-cdr': 



onde, fatti i calcoli analoghi concluderemo che 



!dp=:adp -i-bdq' -i-cdr'....dp=adp-^a'dq-i-aò'r, 

 dq=adp'-i-b'dq' -hc'dr ....dq=bdp-hb'dq-+-b"dr, 

 dr=adp'-hb'dq'-i-c"dr'....dr=cdp^c'dq-^-c'dr. 

 Tomo XXL 2. 



