sentences:  It was developed by the Belgian maker Mahillion in the 1860s based on a slightly earlier design by the Czech maker Červený.The instrument is typically of metal construction, with a conical and unusually wide bore.This width allows each note to be produced by opening only one tone hole, whereas, in other woodwind instruments, several tone holes must be opened to produce most notes (for this reason, all keys but that for the lowest note remain normally closed).