Natural trumpet in the context of "Natural horn"

The natural horn is a musical instrument that is the predecessor to the modern-day (French) horn (differentiated by its lack of valves). Throughout the seventeenth and eighteenth centuries, the natural horn evolved as a separation from the trumpet by widening of the bell and lengthening of the tubes. It consists of a mouthpiece, long coiled tubing, and a large flared bell. This instrument was used extensively until the emergence of the valved horn in the early 19th century.