housing vs tortoise shell

housing

noun
  • A cover or cloth for a horse's saddle, as an ornamental or military appendage; a saddlecloth; a horse cloth; in plural, trappings. 

  • A mechanical component's container or covering. 

  • Residences, collectively. 

  • A niche for a statue. 

  • A houseline. 

  • That portion of a mast or bowsprit which is beneath the deck or within the vessel. 

  • The activity of enclosing something or providing a residence for someone. 

  • An appendage to the harness or collar of a harness. 

  • The space taken out of one solid to admit the insertion of part of another, such as the end of one timber in the side of another. 

tortoise shell

noun
  • The shell of a tortoise, sometimes inaccurately the shell of a turtle, or that material. 

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