This is a very simple question, yet I did not find anybody that could give me a satisfactory answer. I would say “go by foot”, but it seems that “go on foot” is used more often.
Which one is right? Are both right? Does it depend on the context?
Edit: Searching with Google yields 26,000,000 results for “on foot” and 8,000,000 for “by foot”, so it seems that at least both expressions are used. However, whether they are both correct is another issue.
Both expressions convey the meaning, but in my experience and the experience of Google ngram “on foot” is far more common:
“By” tends to be used more for a transport system “by car”, “by plane”. “On” for body parts “on foot”, “on hands and knees” being the only examples I can think of.
Interesting side note “on foot” has become much less common over the last two hundred years according to the NGram: reflective, I think, of our changing means of transportation.