bibcock vs turncock

bibcock

noun
  • An appliance (typically a valve with a threaded outlet) allowing the provision of hose connections outside of buildings. 

turncock

noun
  • A tap or faucet that regulates the flow of a fluid. 

  • A person employed to turn on the water for the mains, to regulate the fireplugs, etc. for a water company. 

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