disquiet vs perturb

disquiet

verb
  • To make (someone or something) worried or anxious. 

noun
  • Lack of quiet; absence of tranquility in body or mind 

perturb

verb
  • To disturb; to bother or unsettle. 

  • To modify the motion of a body by exerting a gravitational force. 

  • To modify slightly, such as an equation or value. 

  • To slightly modify the motion of an object. 

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