During the Victorian era, before embalming, there was a great fear of being buried alive.
Wealthy men and women arranged to have a string tied to their hands that ran from the buried coffin to a bell on the surface, so that if they awoke they could sound the alarm.
The cemetery was busy during the day, but someone was needed to wander the grounds and listen for the bells during the night.
This was called the graveyard shift.
