That name alone is enough to make a person pause. In a rural Irish context, a furnace is rarely domestic; it points instead toward something industrial, something that once demanded sustained heat and considerable effort, whether a forge, a lime kiln used to process limestone for soil improvement, or, most intriguingly in the west of Ireland, a site connected to early iron smelting. The name has survived on the map long after whatever structure or activity gave rise to it has faded from view or from memory.