1968—William Lovelock, in his orchestration text, says the following about trombone

“As was noted regarding the trumpet, trombones are not exclusively noise-makers, though they can drown the rest of the orchestra easily enough and should usually be marked a degree lower then other instruments…. Owing to its construction and technique the trombone cannot get a true legato, since taking two or more notes without a fresh attack each time involves a continual glissando (i.e. slither)…. The trombone can be surprisingly agile provided his slide-shifts permit, but it is necessary to understand them and to be prepared to work them out in detail” (Lovelock 80).