1-4
: 1s and 2s dance Back-to-Back.
5-8
: 1s and 2s turn partner RH 1.1/4, to finish in line of 4 up and down in
  the middle, keeping RH joined, 1L joining LH with 2M. (Order from the
  top: 1M, 1L, 2M, 2L)
9-12
: Balance-in-Line. 1L and 2M turn LH 3/4 , **while** 1M and 2L chase
  clockwise round a quarter, to form a line of 4 across the set.
13-16
: Repeat bars 9 - 12, to finish again in a line up and down the set,
  joining RH with partner.
17-24
: 1M and 2M lead their ladies down the middle, 1s leading, 2s following,
  then 2s divide to let 1s pass up between them, and follow them up,
  ready for
25-32
: Allemande.