Date: 1919. Owner unknown
The 11A Wonder Vocal Cornet has a #1½ bore, which is 0.458". The 11A is the high pitch (A=457 Hz.) version of the 10A, which was low pitch only. Most Conn high pitch brass instruments included both low and high pitch slides. The switch between C and Bb was accomplished by turning a rotor at the base of the vertical tube in front of the first slide.
The valves on the 11A were top spring with sophisticated guides (quite modern for the day). Apparently the 11A high pitch version was half an inch shorter than the 10A. The 10A Wonder Vocal Cornet was produced between at least 1917 and 1927, and possibly longer. Indications are production started sometime during the 1910's.
I have learned that the third slide without the finger ring to adjust the pitch of a low D and C# is slightly longer than it is on modern instruments. On modern instruments the low Eb is in tune, but the low D and C# are quite sharp. On these older cornets with the longer third slide and no finger ring the Eb is a bit flat and the D and C# are slightly sharp, but not as sharp as they are on later instruments. It was thought that the flat Eb and slightly sharp D and C# were within the abilities of the player to lip into tune.
As far as I can tell at this point, all Conn cornets built before 1958 take a short shank cornet mouthpiece as opposed to the 2¾" "Bach-style" long shank cornet mouthpiece. The long shank cornet mouthpieces won't properly fit a pre-1958 Conn cornet and 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 "Improved Precision" 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 (in which case it is a "Precision" mouthpiece). All Conn cornet mouthpieces built before the "Improved Precision" series (ridge), such as the "Precision" series (no ridge) are short shank mouthpieces.
What Conn said in 1927:
The Wonder Vocal cornet is the most practical C, Bb and A cornet ever built, not alone because of its ease of adjustment from C to Bb and A but also for its easy blowing qualities and rich vocal tone when played in C. It is especially suited for choral and home use, as it plays from piano and song scores without transposition. When in Bb or A the Wonder Vocal cornet is a fine cornet for work in bands and orchestras.
According to Conn, the Wonder Vocal Cornet has a bell diameter of 4½", is 16½" long, the valve casing is 5½" long and it weighs 2 lbs. 8 oz.