At the top of the dome, including the tambour (a) and the pendants (b)
A tambourine or dome drum is in the architecture, among other things, a circular or polygonal base on which a dome rests. The tamboer is usually provided with windows and sometimes also of columns, such as St. Peter's in Rome and the Washington Capitol. The architectural advantage of the tambour is that the dome is higher than without a tambour would be the case so that she gets better straight. Also the internal lighting through windows that made it possible played a role. Domes were often placed on the celebration of a church ship, as it occurs at the place where a crossbeam crosses the church ship, or where the vaults of a central building cross each other in the center. The transition from a square construction of such a celebration to the circular of a tambour is called pendently.
The use of tambourines at domes comes from the classic era. In the renaissance, that repetition of classical times, the dome with tambourine was also widely used. A good example of this is the Santa Maria della Salute, designed by the architect Baldassare Longhena (1598-1682). Neoclassicism also has many applications of this type of structure, the former Washington Capitol of which is a famous example.
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