Date: 1921. Museum of brass instruments.
Here is an unusual instrument: a slide cornet. Or, you might call it a soprano trombone? It is my understanding that slide cornets and trumpets are somewhat difficult to play because the positions on the slide are very closely spaced. Notice that the tuning slide is in the hand slide and not in the bell. Both the tuning slide and the hand slide are by necessity cylindrical. Since the cornet is a "semi-conical" instrument, putting the tuning slide in the bell would make it even more cylindrical than it already is turning it more and more into a trumpet. With the tuning slide in the hand slide there is a larger percentage of conical tubing, making it closer to a cornet.
As far as I can tell at this point, all Conn cornets built before 1955 take a short shank cornet mouthpiece as opposed to the 2¾" "Bach-style" long shank cornet mouthpiece. The long shank cornet mouthpieces will fit a pre-1955 Conn cornet, but won't give the proper intonation or playing characteristics of a short shank cornet mouthpiece. All of Conn's "Connstellation" cornet mouthpieces are long shank mouthpieces. The "standard" (my term) Conn mouthpieces such as the Conn 4 are long shank if there is a "ridge" halfway down the shank, and short shank if there is no ridge. Also, the long shank mouthpieces have "Conn" and the number of the mouthpiece stamped across the mouthpiece, whereas the short shank mouthpieces have it stamped along the length of the mouthpiece. All Conn cornet mouthpieces built before the "standard" series, such as the "Wonder" and "AI-412" are short shank mouthpieces.
The August 1899 copy of the "C.G. Conn Truth's" magazine shows a "New York Wonder Cornet Slide Trombone", which is essentially identical to this instrument except for the bell brace which is angled.
The Wonder slide cornet Weighs 1 1/2 lbs, is 21 1/4" long and has a 4" bell. The 16A is the low pitch version, the 17A is the high pitch version. As far as I can tell the name "Wonder" was dropped sometime in the late 1920's. It was produced between at least 1904 and 1927.
What Conn said in the 1920's:
In vaudeville and jazz orchestras this slide cornet is used to produce startling glissando and novelty effects. It is also being used effectively in brass bands, for little tots, as a sort of trombone substitute.