aerator vs contrivance

aerator

noun
  • A device which mixes air with a substance, particularly soil or a liquid. 

  • A fumigator used to bleach grain, destroying fungi and insects. 

  • A device used for charging mineral waters with gas and in making soda water. 

contrivance

noun
  • A (mechanical) device to perform a certain task. 

  • Something overly artful or artificial. 

  • A means, such as an elaborate plan or strategy, to accomplish a certain objective. 

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