A windmill is an edifice for drawing power from the wind, consisting of a roofed tower supporting four sails on a central axis.  The sails are set saltirewise by Society default.

The windmill was used in the rebus badge of Kingsmill, 1557 [Siddons II.2 336].  A pair of windmill’s sails alone were also used, in the arms of Newmarche, c.1460 [RH], and as the badge of Willoughby, 1449 [HB 157].  See also whirligig.

The Baron of Delftwood bears:  Quarterly azure and argent, a windmill, sails crosswise, and in sinister chief a laurel wreath counterchanged.

Alis of Tuscon bears:  Quarterly azure and argent, a windmill gules, vanes throughout and set saltirewise Or.

Marcos de Valencia bears:  Or, three windmills purpure.