central vs telephone exchange

central

noun

  • centre 

adj

  • Having or containing the centre of something. 

  • Being in the centre. 

  • Exerting its action towards the peripheral organs. 

  • Being very important, or key to something. 

telephone exchange

noun

  • the rooms housing such equipment 

  • any equipment that establishes connections between telephones 

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