harpoon vs impale

harpoon

verb
  • To shoot something with a harpoon. 

noun
  • A spearlike weapon with a barbed head used in hunting whales and large fish. 

  • A harmonica. 

impale

verb
  • To pierce with a pale; to put to death by fixing on a sharp stake. 

  • To pierce (something) with any long, pointed object. 

  • To place two coats of arms side by side on the same shield (often those of two spouses upon marriage). 

  • To enclose or fence with stakes. 

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