Bebop was probably the worst thing ever to happen to the trombone. While the blockish rhythms and rough-hewn sonorities of early jazz were tailor-made for -- and in part, defined by -- the infinitely flexible instrument, the technical requirements of modern jazz just about put it out of business. Over the years, a number of very fine players (J.J. Johnson and Frank Rosolino being, arguably, the foremost among them) managed to adapt the instrument to the exigencies of bop. In the process, however, they were usually forced to sacrifice the peculiar tonal expressivity that sets the trombone apart from other jazz instruments. It wasn't really until the advent of free jazz that trombonists reclaimed the slides, smears, growls, and groans that had virtually disappeared from the current of jazz's development for some 20-plus years. It's no coincidence that free jazz's most acclaimed trombonist, Roswell Rudd, mostly bypassed bop altogether, going straight from being a tailgate trombonist in a Dixieland band to co-founding the ultra avant-garde New York Art Quartet, with very few stops in between. Rudd exploited the trombone's natural proclivities to the fullest. In his hands, the horn became less a note-playing machine than a kind of human-powered analog synthesizer. Rudd didn't try to mimic a language, bebop, that was spoken most naturally by players of keyed instruments. Instead, he jumped wholeheartedly into free jazz -- a type of music more concerned with exploring sound for its own sake -- a style for which he and his instrument were exceedingly well equipped.