bowstring vs send to the gas chamber

bowstring

noun

  • The string of an archer's bow. 

  • The string of an archer's bow, as used by the Turks for strangling offenders. 

verb

  • To strangle with a bowstring. 

send to the gas chamber

How often have the words bowstring and send to the gas chamber occurred in a corpus of books? (source: Google Ngram Viewer )