Kohler Cornet with Disc Operated Valves c.1840

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It has been my objective to collect and exhibit brass horns with all variations of valve and key systems.  There is, however, one system that eludes me - both in rarity and in price - Disc Operated Valves.

The disc valve is characterized by the use of two discs facing each other, one fixed, the other rotating. The rotating disc either blocks the valve slide (left) or allows free passageway to it (right), hence increasing the overall tube length of the instrument.

Originally patented by John Shaw in 1838, an improved disc valve was subsequently introduced by John A. Köhler, who called it the "New Patent Lever Valve." However, the same principle was already known in France in 1835 as plaque tournantes or disques mobiles, where it was developed by the Parisian maker Halary. The plaque on this cornet reads "Kohler, Sole Maker, Henrietta St, Covent Garden, London".

In the photographs below, the rotating discs are operated by vertical spring loaded push rods. The discs are limited in their rotation by cork stops - similar to modern rotary valves.  The first valve lowers the pitch a whole tone. The second valve lowers the pitch a semitone, and the third valbe a minor third. The first and third valves have inner moving slides while the second valve has outer moving slides.  Please scroll way down to see an example of a dis-assembled valve.

The photos of this  horn are displayed with the kind permission of Mr. Maximilian Goldgruber of Munich who has a wonderful collecction of brass instruments which I hope to visit one day!