Vāne, n.

n. [O. & Prov. Eng. fane, a weather-cock, a banner, A-S. fana, O. H. Ger. fano, N. H. Ger. fahne, M. H. Ger. van, D. vaan, banner, Goth. fana, cloth.]

1. A fixture attached to some elevated object for the purpose of showing which way the wind blows; usually a plate or strip of metal, or other material, often cut into some fanciful form, and placed upon a perpendicular axis around which it moves freely.
2. Any flat, extended surface moved by the wind; as, the vane of a windmill; hence, a similar fixture moved in or by water; as, the vane of a screw-propeller.
3. The thin, membranous part or web of a feather, on the side of the shaft.

Vane of a leveling staff (Surv.), a piece of board or metal, usually painted in alternate quarters black and white, and arranged so that it can be raised or lowered at pleasure to indicate the point on the staff at which the plane of apparent level through the axis of the telescope cuts it. Math. Dict.