contrivance vs telephone exchange

contrivance

noun
  • A (mechanical) device to perform a certain task. 

  • Something overly artful or artificial. 

  • A means, such as an elaborate plan or strategy, to accomplish a certain objective. 

telephone exchange

noun
  • any equipment that establishes connections between telephones 

  • the rooms housing such equipment 

How often have the words contrivance and telephone exchange occurred in a corpus of books? (source: Google Ngram Viewer )