The furnace proper or fire box, being the chamber in which the solid constituents of the fuel and the whole or part of its gaseous constituents are consumed.
The grate, which is composed of alternate bars and spaces, to support the fuel and to admit the air.
The dead-plate, that part of the bottom of the furnace which consists of an iron plate simply.
The mouth piece, through which the fuel is introduced and often some air. The lower side of the mouth piece is the dead plate.
The fire door: Sometimes the duty of the fire door is performed by a heap of fuel closing up the mouth of the furnace.
The furnace front is above and on either side of the fire door.
The ash pit. As a general rule the ash pit is level, or nearly so, with the floor on which the fireman stands, and as for convenient firing, the grate should not be higher than 28 to 30 inches, the depth of ash pit is thereby determined.
The ash pit door is used to regulate the admission of air.
The bridge wall.