Date: 1917. Owner unknown
This is the "High & Low Pitch" version of the 80A. As can be seen in the picture, it has slides for both high pitch (A=452 hz) and low pitch (A=440 hz). The 81A has a "mechanism" (see the Dictionary). The bore size of the 81A is #2½ (0.484"). Read the booklet Conn included with these instruments, entitled What you should know about this instrument for more on the "mechansim", the micro-tuning mechanism (a.k.a. opera glass tuning slide) and the adjustable spring strength.
I have learned that at least the pre-war 80A takes a short shank cornet mouthpiece. Apparently modern cornet mouthpieces are long shank. I am told the long shank mouthpieces will work, perhaps with the help of a little tape, but the short shank mouthpieces work a lot better. I have also 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 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.