Luffer

These luffer boards are either fixed, or turn on pivots in the styles of their frames; their action, in the latter case, being like that of the common Venetian blinds.

Source: wiktionary

In the section, the third luffer is supposed to be open; when the lower luffer plate is taken out, the apparatus is to all intents and purposes a Staffordshire grate.

Source: wiktionary

Functional and symbolic values coincide; if there rises a column of smoke to the luffer above, this is not merely a convenience, but also a representation of the axis of the universe that pillars-apart heaven and earth, essence and nature, and is itself although without dimensions or consistency the adamantine principle and exemplary form of temporal and spatial extension and of all things situated in time or space.

Source: wiktionary

We meet again with a pair of annular symbols, of which the one is a perforated disk representing the Earth (Holmberg, "Der Baum des Lebens," fig 13), and the other the luffer above the central hearth of the yurt, which is also the opening in the roof of a hypaethral temple, through which passes the stem of the Worldtree to branch above.

Source: wiktionary