{{explanation}}
Each couple dances 80 bars. A new couple starts after 40 bars (ie on bars 41, 81 & 121)

1-8
: 1s lead down for 3 bars, back to top & cast to 2nd place
9-16
: 1s dance 1/2 Fig of 8 round 2s, set advancing & 1/2 turn 2H into double
  triangle position
17-24
: 2s+1s+3s set & 1s+2s change places, set again with 1s+2s advancing into
  middle facing up
25-32
: 1s+2s dance Allemande
33-40
: All dance 8H round & back
41-48
: (New Couple starts as at bar 1) **while** 1s (original) continue casting
  to bottom, turn RH & cast up to 3rd place
49-56
: 1s (2s) dance 1/2 Fig of 8 round 4s (3s), set advancing & 1/2 turn 2H
  into a double triangle position (nearer hand joined with new dancing
  couple  - 2s)
57-64
: All set & 1s+4s change places, All set again & all advance into middle
  facing up
65-72
: 1s+4s (also 2s+3s) dance Allemande
73-80
: All dance 8H round & back.

{{explanation}}
Note: First time through only 1st couple dance bars 1-40.  Last time through only 4s dance bars 41-80