on foot vs roving

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. 

roving

noun
  • A long and narrow bundle of fibre, usually used to spin woollen yarn or in felting. 

  • The process of giving the first twist to yarn. 

adj
  • Of the eyes or gaze, inspecting all over; not staying fixed on on subject. 

  • Moving about; having no fixed or permanent abode; travelling from place to place. 

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