History of trombone

My tenor trombone

The history of the trombone is unclear, but it's agreed upon that its immediate precursor was the sackbut, a term which refers to any brass instrument with a slide.  The earliest trombone was in 1551, and was closer to contemporary trumpets than modern trombones.  Its melancholy timbre in the 17th century meant it was associated with death and the underworld.  However, it almost disappeared in the 18th century due to a lack of interest.

In the 18th century, the trombone began to reappear, mainly in Mozart pieces and military bands.  Several changes were made to the instrument after this time.  In the late 1700s, the Bb trombone with 7 slide positions (vs. the previous 4) was developed.  In the early 19th century, the bell was widened and the bore (interior chamber) was enlarged by 20 - 30%.  By the middle of the century, it was common to have two tenor trombones and one bass trombone in an orchestra.  By the 20th century, it was also popular in jazz and swing bands.

Trombones with triggers include
the tubing highlighted in blue.

A trombone has seven slide positions; 1st position is when the slide isn't extended at all.  Some trombones also include an additional set of tubing, accessible by a trigger, which drops the pitch a fourth.  This extends the compass of the instrument and allows the player to play certain notes in more than one slide position (more so than you could with a trombone without a trigger.)

The trombone family consists of the alto, tenor, and bass trombones.  The alto trombone has a compass of A to e'', and the tenor and bass trombones have a compass of E to f'''.  The tenor trombone sounds an octave below the Bb trumpet and an octave above the tuba.  The alto trombone sounds a fourth or fifth (depending on the key of the instrument) above the tenor.

The compass of the tenor
and bass trombones