|a simple valveless natural horn consisting of a long tube of brass or copper, either straight or coiled; formerly often used to announce the arrival of a mailcoach|
brass musical instrument of cylindrical bore, used by guards of mail coaches in the 18th and early 19th centuries. At the end of the 18th century, post horns were crescent-shaped, coiled, or straight. The notes they sounded were at most six (harmonics 2 to 7). The post horn gave rise to the cornet in the 19th century, when valves were applied to it.
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