TubeNet

If the image was reversed, it would be played with the left hand, so it seems unlikely.

The valves-in-increasing-length was used and known as the "Bavarian" system.

http://home.att.net/~bobbeecher/bari-eu ... -euph.html

(see: about halfway down, "Four rotor-valve trombone
by Anton Schöpf, Landshut, ca. 1885"

Looks to me like a Bavarian-system OTS horn, with a bigger bell, possibly, but modified for upright performance by adding a gooseneck.

Yes, but look how close-in the original tuning slide is. Perhaps these were mods for when after the war was over...

(and no, you don't mess with someone who can hold THAT mess perpendicular, MR. TUBA PLAYER, SIR!)