This design (shown in detail below) is an
improvement over the 1897
D.R.G.M. 84 240 in that it combines the the
twin tandem rotors connected by a rod into one double
rotor similar to the double rotors of the main valves.
The difference is the lack of a separate lever with
linkage to the rotor shaft. Here a simple lever
connected directly to the rotor shaft is pushed
horizontally by the player's thumb. One example
of this horn is found in the collection of the Musikwisssenschlaftilishes
Institute of Eberhard Karls Universität Tübingen
described as follows:
Doppelhorn in F1/B1, Ed. Kruspe, Erfurt, 1902 (ex B
Deutsches Reichs-Gebrauchsmuster 182267, 3
This specimen is missing the lever on the change valve
rotor, but it's application is shown in the diagram
below. Much later a double horn with this type
of change valve was marketed by the Boston
Musical Instrument Company. No known copies of
the original documents for D.R.G.M. 182 267 exist. It
was superseded two years later by the now familiar D.R.G.M.
232 038 found on the Kruspe "Horner Model."