on foot vs travelling

on foot

prep
  • In progress or in preparation; active, in operation. 

  • On one's feet; walking, jogging or running but not in a vehicle or on the back of an animal. 

travelling

adj
  • That travels (with one) 

noun
  • The act of one who travels; a journey. 

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