pushpin vs rivet

pushpin

noun
  • A thumbtack, especially one with a cylindrical head. 

verb
  • To fasten with a thumbtack. 

rivet

noun
  • A cylindrical mechanical fastener that attaches multiple parts together by fitting through a hole and deforming the head(s) at either end. 

  • Any fixed point or certain basis. 

verb
  • To command the attention of. 

  • To attach or fasten parts by using rivets. 

  • To make firm or immovable. 

  • To install rivets. 

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