Date: 1924. Owner unknown
Unless I am seriously mistaken, this is what is called in the model number list "14H Bass with Piston Valve to F&E. Tuning slide in slide only." Which according to Dr. Banks is the "New Invention Bass with Piston Valve in Bb/F (low pitch), that was produced from about 1910-1921. Built with piston valve to F. Large bore. Bell 8" or 8 1/2" in diameter. Professional model. Becomes New Wonder bass with piston valve in Bb/F." Presumably it was renamed "14H" around 1920 or so when you start to see the model numbers coming up. Since the instrument pictured here is a 1911 model, it would stand to reason that at that time it was still called the "New Invention".
What Conn said in 1919:
The New Wonder BASS Slide Trombone is a most necessary instrument in any good sized Band or Concert Orchestra. It has been too seldom in evidence in American organizations. It will, however, be found in all our leading Concert Bands, Symphony and Grand Opera Orchestras. The need of the Bass trombone is primarily to fill the gap between the smaller trombones and the Basses. It adds to the sonoriy of lower tone color of the music rendered and possesses a quality all its own which is most pleasing. The Conn Bass Trombones can be furnished with either the Piston or Rotary valve.
The instrument is built in Bb and by the use of the valve it is thrown in the key of F. It is seldom if ever ordered in high pitch but can be furnished in that pitch or the more preferably low pitch as desired. The Conn Bass Trombones are used in most all of the leading Symphony Grand Opera Orchestras and Concert Bands of America. They are pronounced as far surpassing those of other makes. The Conn factory specializes in Bass Trombones.
NOTE: On special order we can furnish the Bass Trombone in G and F, in Eb or in BBb as desired.