To make brass instruments chromatic--the idea that the valve was invented as a "mere crook changing device" is a myth.
This article is based on materials published in The Horn Call 28, no. 3 (May, 1998), with related materials to be found published in the Historic Brass Society Journal 9 (1997).
A major point that has frequently been made in the existing literature on the early valved horn is the idea that the valve was invented only to make quick changes of crook--to eliminate the need for the loose crooks of the natural horn to change key--and that only later did hornists realize the chromatic possibilities of the valve. Many sources state this as a fact, and when I started my own research into the history and technique of valved and natural horns in the nineteenth century I thought that it should be very easy to find evidence to support this idea. But the evidence is just not there. Jeffrey Snedeker observed in his 1991 study of Meifred and early valved horn technique in France that "In view of the various comments and accounts surrounding Stölzel's invention and its initial use, it is clear that perhaps an argument as to Stölzel's original intent could be revived." I must second his statement. After examining the evidence I have been forced to conclude that the idea that the valve was invented as a mere crook changing device is a myth. The earliest sources are unanimous in stating that Stoelzel and Blühmel, the co-inventors of the valve, clearly intended to perfect the brass instruments by making them chromatic.
Heinrich Stoelzel (1777-1844), a member of the band of the Prince of Pless, invented a valve which he applied to the horn by July of 1814 [Heyde, part 1, 30]. See Figure One.