What is a cortley trombone?

A cortley Trombone is not a widely recognized term in the context of Musical Instruments. It may be a misspelling or misinterpretation of another term, such as "cortale" or "slide trombone." If you're referring to a specific brand or model of trombone, clarification would be helpful. Generally, trombones are brass instruments known for their slide mechanism that changes pitch.