Ruddy Gore - S1-E6
Revealing mistake: It is revealed that the ghost apparitions come through thanks to projection over falling sand, but that's not the trick used in the actual movie shoot: no sand is falling and accumulating on the floor in the last ghost apparition (when we can see the floor for a while) and in the second apparition (to Miss Fisher backstage) the line of sand was in the wrong direction for it to act as screen.
Answer: Louisa's watch was broken during the struggle to get away from her attacker.
Bishop73