I assumed that since hobbits tend to walk everywhere, and Sam, uh… probably would’ve liked trains, he had a habit of counting his steps when he’d gone somewhere, and knew he was about to take the largest number of steps. Though this wouldn’t necessarily give him true distance, I don’t suppose something like that would concern a hobbit (I choose to believe that they only measure distance in how far it is to walk, not physical distance)
I just assumed he was there before and remembered he didn’t go over that field.
I assumed that since hobbits tend to walk everywhere, and Sam, uh… probably would’ve liked trains, he had a habit of counting his steps when he’d gone somewhere, and knew he was about to take the largest number of steps. Though this wouldn’t necessarily give him true distance, I don’t suppose something like that would concern a hobbit (I choose to believe that they only measure distance in how far it is to walk, not physical distance)