Date: 1924. Picture by G. Scott Hansen
Notice the micro-tuning mechanism or "opera glass" just forward of the first valve. This 84A does have the mechanism that automatically adjusts all slides when the main tuning slide is pulled out to A. It also has adjustable tension top spring valves. This particular instrument is gold plated. The 84A had a #1 (0.438") bore and was produced between 1918 and 1924.
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 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.