kindling vs smouldering

kindling

noun
  • The act by which something is kindled. 

  • Small pieces of wood and twigs used to start a fire. 

adj
  • Illuminated, lit. 

smouldering

noun
  • The act by which something smoulders; residual heat. 

adj
  • Burning slowly, producing smoke but no flame. 

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