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

1-8
: 1s & 4s set, turn RH, cast in 1 place & 1/2 turn RH into prom hold (Lady
  on left) to face 2L/3L
9-16
: 1s+4s dance Pass+Turn with 2L+3L & Pass+Turn with 2M+3M ending 1s
  between 2s facing down & 4s between 3s facing up
17-24
: All set in lines of 4 & 1s+4s change places LH with opposite partner, 4s
  & 1s lead out ends crossing RH & cast back to 2nd/3rd places
25-32
: 1s+4s change pl LH on sides dancing into centre, 1s & 4s lead out ends
  cross & cast (1s own sides, 4s opp sides) & dance 1/2 RH across. 2
  4(1)(3)