cloche vs cloche hat

cloche

noun
  • A tableware cover, often resembling a bell. 

  • A glass covering, originally bell-shaped, for garden plants to prevent frost damage and promote early growth. 

  • An apparatus used in controlling certain aeroplanes, consisting principally of a steering column mounted with a universal joint at the base, which is bell-shaped and has attached to it the cables for controlling the wing-warping devices, elevator planes, etc. 

  • A bell-shaped, close-fitting women’s hat with a deep rounded crown and narrow rim. 

cloche hat

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