Conn 18B C, Bb & A "Glantz" Model
Date: 1934 or 1936. Owned by Ralph Henssen.
The 18B "Glantz" model was essentially the same as a 14B Symphony C "Glantz", except that it also had slides for Bb & A. In the picture above the Bb & A slides are in below the instrument; the instrument itself is configured with as a C trumpet.
The instrument pictured here is almost certainly a prototype. It is raw brass, not engraved. As for the date being "1934 or 1936": the serial number stamped on the valve casing dates it to 1934. However, the Bb main tuning slide has engraved on it "MODEL 10-8-36", suggesting a date of October 8th, 1936. That would correspond nicely with the year production of the 18B was supposed to have started.