paddlewheel vs water wheel

paddlewheel

noun
  • A large wheel fitted with thick slats, turned by an engine and used to propel a boat. 

  • A boat propelled by a paddlewheel. 

water wheel

noun
  • A wheel, propelled by running or falling water, used to power machinery. 

  • A wheel with buckets used to raise water. 

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