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. The only known 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 22).
Deutsches Reichs-Gebrauchsmuster 182267, 3 Drehventile.
Unfortunately this horn is missing the lever on the
change valve rotor, but it's application is easily
inferred as 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superseded two years later by the now familiar D.R.G.M.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."