The method was that the shears were stuck in the rim of a sieve, and supported by two people on their fingers. They would then ask the apostles Peter and Paul if certain people had taken the missing object, and the sieve would turn around at the nomination of the guilty party.
Although the earliest description in Britain was Reginald Scot's Discoverie of Witchcraft in 1584, the general method is recorded as far back as Ancient Greece, and is referred to by the poet Theocritus in his Idylls.