Original sentence: ” contains the text: “Workmen, too, were set to search and dig everywhere for "Tewkesbury mustard-balls," as they were called--or fire-balls, with which it was thought that the Catholics would set London a-fire” which suggests that the term was used to describe some sort of early day incendiary device
Edited sentence: ” contains the text: “Workmen, too, were set to search and dig everywhere for "Tewkesbury mustard-balls," as they were called—or fire-balls, with which it was thought that the Catholics would set London a-fire” which suggests that the term was used to describe some sort of early day incendiary device