hydrant vs turncock

hydrant

noun
  • An outlet from a liquid/fluid main often consisting of an upright pipe with a valve attached from which fluid (e.g. water or fuel) can be tapped. 

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 hydrant and turncock occurred in a corpus of books? (source: Google Ngram Viewer )