{{explanation}}
2s start on opposite sides

1-8
: All set on sides, dance Do-Si-Do with partners, all set
9-12
: All Men dance RH Across
13-16
: All Ladies dance LH Across, finishing facing out
17-24
: All set, NHJ in 'circle' (Triple Triangles). All change places RH to
  "invert" (Men facing out, Ladies facing in), Set, change places LH to
  "invert" (Men facing in, Ladies out)
25-32
: All set, all change places with RH, all set, all change places LH into
  circle, all facing in 3 (1) 2
33-40
: Circle 6H round & back