carburetor vs carburettor

carburetor

noun
  • A water pipe or bong; a device or contrivance for mixing air with burning cannabis or cocaine. 

  • A device in an internal combustion engine where fuel is vaporized and mixed with air prior to ignition. 

carburettor

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