Mass or scratch dials are a simple early type of sundial found on churches, often on the south side, which gets the most sun. They are referred to as scratch dials because they are often crudely made, and mass dials because they are believed to have indicated (when the sun was shining) the times of services. Their use, however, is not fully understood, and they vary in the time periods they seem to denote. Also, some churches have several of them, occasionally placed close together.
It is not that unusual to find a mass dial inside a church, or outside on the north side, where clearly it cannot have worked. This can be explained by the dial being moved from its original position when the wall it was on was demolished or altered – the piece of stone simply being re-used during rebuilding. The positions of some though suggest that the dial may have retained some significance, even if no longer functioning as a time marker. For example those at Woodbury and Topsham (Devon) are just inside the south doorways – perhaps deemed to be close to their original sites. Although there is another apparent former dial at Woodbury, next to the door inside the bell ringing chamber.