king post vs palisade

king post

noun
  • A central vertical supporting post used in architecture and bridge as well as in aircraft and ship design. 

palisade

noun
  • A wall of wooden stakes, used as a defensive barrier. 

  • An even row of cells. e.g.: palisade mesophyll cells. 

  • A line of cliffs, especially one showing basaltic columns. 

  • A long, strong stake, one end of which is set firmly in the ground, and the other sharpened. 

verb
  • To equip with a palisade. 

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