What's the difference between "farther on", "ahead" and "farther ahead" in these examples related to physical locations? For example; does one of them denote a greater distance or a more literary/old-fashioned style than another? Doing some Google searches I learned that "ahead" is the most popular.
Tim was walking by the river when, 20 yards ahead/farther on/farther ahead, he saw a deer galloping past.
Ahead/Farther ahead/Farther on in the misty distance there gleamed a fire.