{{explanation}}
3s & 4s start on opp sides

1-8
: 2s & 3s dance out ends & cast in to meet other partner in prom hold,
  2s+3s dance 1/2 RSh reels of 3 on sides (dancing to right) & end in
  prom hold with own partner in 2nd/3rd place (2s face up 3s down) (4) 2
  (3) 1
9-16
: 2s dance LSh reel of 3 across with 4s **while** 3s dance LSh reel across
  with 1s ending in prom hold with other partner & curving round to
  right (3M+2L face up, 3L+2M face down)
17-24
: 2s+3s (dancing out ends) dance 1/2 LSh reels of 3 on sides ending on
  sides order 13(2)(4) in Sq.Set formation, all set & 1s+3s also 4s+2s
  1/2 turn 2H on sides to end on corners of square
25-32
: All set diagonally & circle 8H round to left. 3 1 (4)(2)