natural trumpet vs trombone

natural trumpet

noun
  • A valveless brass instrument that is able to play the notes of the harmonic series. 

trombone

noun
  • A musical instrument in the brass family, having a cylindrical bore, and usually a sliding tube (but sometimes piston valves, and rarely both). Most often refers to the tenor trombone, which is the most common type of trombone and has a fundamental tone of B♭ˌ (contra B♭). 

  • The common European bittern. 

  • A kind of extendable support for attaching lighting elements to a set. 

verb
  • To extend and retract (the zoom lens); to use it too enthusiastically. 

  • To transmit a signal or data back to a central switching point before sending it out to its destination. 

How often have the words natural trumpet and trombone occurred in a corpus of books? (source: Google Ngram Viewer )