cattle prod vs impel

cattle prod

verb
  • To goad or push someone to act. 

noun
  • Something used to goad or push someone to act. 

  • A stick designed to goad cows, steers, and similar animals in order to prompt them to move in a desired direction, now usually electrified to administer a stimulating shock to the animal. 

impel

verb
  • To urge a person; to press on; to incite to action or motion via intrinsic motivation. 

  • To drive forward; to propel an object, to provide an impetus for motion or action. 

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