{{explanation}}
On 2nd chord 1c+3c cross to opposite sides (1x,2,3x,4)

1–
: Parallel Reels4 on the sides
9–
: 1c+4c dance clw ½ round set, **while{4}** 2c+3c ½ LHA | 2c+3c change LH on the sides ; 4c+2c & 3c+1c RHA (4x,2x,3,1)
17–
: 2c+3c Half Petronella, at end 2c face 4c and 3c face 1c. (4x,2,3x,1)
25–
: Progressive Half Petronella: 4c+2c & 3c+1c Petronella Turn to face each other in line4 across | set ; Petronella Turn | set (2,4x,1,3x)

{{explanation}}
Note: Compared with the start, M and W have changed sides