soothing vs tranquil

soothing

adj
  • Freeing from fear or anxiety. 

  • Giving relief. 

  • Tending to soothe. 

noun
  • The act by which somebody is soothed. 

tranquil

adj
  • Free from emotional or mental disturbance. 

  • Calm; without motion or sound. 

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