TYMPAN
, or Tympanum, in Architecture, is the area of a pediment, being that part which is on a level with the naked of the frize. Or it is the space included between the three cornices of a triangular pediment, or the two cornices of a circular one.
Tympan is also used for that part of a pedestal called the trunk or dye.
Tympan, among Joiners, is also applied to the pannels of doors.
Tympan of an Arch, is a triangular space or table in the corners of sides of an arch, usually hollowed and enriched, sometimes with branches of laurel, olive-tree, or oak; or with trophies, &c; sometimes with flying figures, as fame, &c; or sitting figures, as the cardinal virtues.
Tympan, in Mechanics, is a kind of wheel placed round an axis, or cylindrical beam, on the top of which are two levers, or fixed staves, for more easily turning the axis about, in order to raise a weight. The Tympanum is much the same with the peritrochium; but that the cylinder of the axis of the peritrochium is much shorter and less than the cylinder of the Tympanum.
Tympanum of a machine, is also used for a hollow wheel, in which people or animals walk, to turn it; such as that of some cranes, calenders, &c.
