Conn Unknown Model Bb & C Large Bore (high and Low Pitch)
Date: 1914. Instrument owned David Watt.
Here is an "unknown model", produced before Conn started using model names around 1920. The 1919 catalog doesn't show a model similar to this one. It is a #2½" (0.485") bore, Bb and C, High and Low pitch instrument. The High and Low pitch works by way of an insert slide before the main tuning slide. The two braces visible in the picture are attached to a removable slide. The slides installed on the instrument in the picture are the Bb slides, the slides in front of the instrument are the C slides. Apparently the receiver on this instrument is not original.
This instrument was apparently also available in a cornet version. See: Unknown Model Bb & C cornet. Combining these and one other trumpet version I am aware of, they were made between at least 1911 and 1914.