oar vs sculler

oar

noun
  • A type of lever used to propel a boat, having a flat blade at one end and a handle at the other, and pivoted in a rowlock atop the gunwale, whereby a rower seated in the boat and pulling the handle can pass the blade through the water by repeated strokes against the water's resistance, thus moving the boat. 

  • An oarsman; a rower. 

  • An oar-like swimming organ of various invertebrates. 

verb
  • To row; to travel with, or as if with, oars. 

sculler

noun
  • A boat rowed by one person with two sculls, or short oars. 

  • One who sculls; an athlete who participates in sculling races. 

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