inscribe vs slip in

inscribe

verb
  • To write or cut (words) onto (something, especially a hard surface, or a book to be given to another person); to engrave. 

  • To draw a circle, sphere, etc. inside a polygon, polyhedron, etc. and tangent to all its sides. 

slip in

verb
  • To include (e.g. a certain word or phrase) into a sentence discreetly 

  • To enter discreetly 

  • To play a subtle pass into someone in a goalscoring position. 

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