Conn 40B Connqueror
Date: 1932. Instrument owned by Paolo Petrozziello. Picture by Paul Ayick.
Notice the vocabell (rimless), the octagonal valve casings and the position of the third slide finger ring. In case you are wondering: the valves themselves aren't octagonal. Also note that the position of the third valve slide and the tuning slide on the third valve casing are reversed from the usual/modern way.
Apparently the instruction manual said of the valves: "Use distilled water on the valves. Only inferior horns need oil lubricant". The 40B has a #1½ (0.459") bore, and was produced from 1932 to 1941.
In the following video clip band leader Erskine Hawkins takes two turns soloing on a Conn 40B Connqueror. The song is called "Swinging in Harlem".
What Conn said in 1933:
The most popular trumpet on the market. Used by such first chair stars as Lebert Lombardo (Guy Lombardo), Jack Cavan (Charlie Agnew), Lamar Wright (Cab Calloway), Charlie Williams (Duke Ellington), David Glickstein (Broadway shows) and Eddie Camden (Don Bestor). The Vocabell rim is a single, integral piece of metal which allows it to vibrate freely. Conventional bells have a rigid wire in the rim which tends to muffle the tone and dampen out the delicate harmonics that are so essential to clear tone and rich coloring. Delicate instruments of Columbia Broadcasting Studio in New York show the Vocabell has from 12 to 15 decibels greater volume, is smoother and more even in scale, and is clearer and purer in tone than trumpets with the conventional type bells. Beautifully styled in modern manner. Medium bore, Bb and Am springs in bottom of valves.