Conn 18B C, Bb and A (Low Pitch)
Date: 1925. Owner unknown.
Other than the convenient extra slides this instrument lacks a feature seen on all trumpets these days: a pinky ring for the right hand. It didn't come off some time over the years.... it was never there in the first place. This was quite common in the 20's. The 18B is low pitch, the 19B is the high pitch variant. I have learned that the 18B is a "duo bore" instrument: the bore on the main tuning slide is 0.406" ("#0 bore") going into the main tuning slide and 0.438" coming out (#1 bore). The First valve slide is 0.438" (#1 bore), second valve slide unknown, the third valve slide is 0.480" on top and 0.438" on bottom.
What Conn said:
Like the Vocal Cornet, the C, Bb and A trumpet is in every sense of the word a utility instrument. It is a real trumpet, having a properly graduated bore which has been ingeniously arranged so that the introduction of the tuning slides does not interfere with the quality of the tone, and consequently it offers the real trumpet tone for which all C.G.Conn trumpets are famous. When in C this instrument can be for playing vocal, piano or violin parts without transposition, and when in Bb or A it becomes almost indentical to the 22B Symphony trumpet, having the same bore.
The instrument has a 4½" bell, weighs 2¼ lbs. and is 18½" long.