The Cambridge Butterfly        
Dance: Colin Hume, 2008, revised 2011, 2023.
Tune: Traditional Irish.  Each line is 4 bars of slip-jig. 9/8 
https://www-ssrl.slac.stanford.edu/~winston/mydances/The_Butterfly.PDF

A1:	Lines forward and back.  Ones cross and cast (twos meet and lead up).
A2:	Lines forward and back.  Twos cross and cast (ones meet and lead up).
B1:	First corners positions meet, clap both hands with each other on beat 3; fall back 3 steps.  Cross right, turn right.
B2:	Second corner positions meet and clap; fall back.  Cross right, turn right.
C1:	Circle left.  Circle right.
C2:	Four changes of a circular hey with hands.