Running step is used throughout
Note: Cosh explicitly tells 1c to pass Lsh in [9-24]; however the Rsh pass is quite common, and nicknamed »Mairi's Divorce«.
2 chords. On 2nd chord 1W crosses down to R of P, 2W moves 1 place up and 2M crosses to her place, so 1c faces 2c across.
Notes: The RSCDS prescribes a 4c set, but the tradition is a longwise set 'for as many as will'.
Note: on  the original says »RH«, but »BH« is widely used.
Unofficial: On 2nd turn, 4c has an easier next start if 1c+3c+4c dance a 3C Poussette
Note: The dry white sands on the north-west side of the Isle of Eigg are said to produce a musical sound when walked upon.