Crook horn (Inventionshorn)

What it means

The crook horn (German Inventionshorn) is a natural horn fitted with interchangeable tubing sections of different lengths, called crooks or “inventions.” By exchanging these crooks the instrument could be retuned into different keys without needing another horn.

Musical use

The improvement is attributed around 1750 to the Dresden horn player Anton Joseph Hampel, who thus responded to the practical limits of the rigid natural horn, playable only in one fixed key. Since the horn still had no valves, only the notes of the harmonic series remained available; Hampel also developed the hand-stopping technique in the bell to produce additional intermediate notes. The crook horn became the standard instrument of the Classical period until it was replaced in the 19th century by the valve horn.

The crook horn should be distinguished from the simple natural horn without interchangeable crooks, which needed a separate instrument for each key, and from the later valve horn, in which valves rather than exchanged crooks determine the key and the playable notes. It also differs fundamentally in construction principle from today's double horn in F and B-flat.

Performance practice

If you play a crook horn or listen to a historical performance, note the difference in sound between open natural notes and stopped notes, which sound more muffled and somewhat different in color. Practise changing the crooks as a fixed part of preparation, since it determines the playable key of the whole piece.