BROOD v.
To sit on and cover eggs, as a fowl, for the purpose of warming them and hatching the young; or to sit over and cover young, as a hen her chickens, in order to warm and protect them; hence, to sit quietly, as if brooding. Birds of calm sir brooding on the charmed wave. Milton.
FURNACE n.
h heat is produced by the combustion of fuel, as for reducing ores or melting metals, for warming a house, for baking pottery, etc.; as, an iron furnace; a hot-air furnace; a glass furnace; a boiler furnace, etc.