A man who had no wristwatch or pocket watch had a very accurate wall clock that only stopped when he forgot to wind it up.
When this happened, he went to his friend's house, spent the afternoon with him and when he returned he set the clock.
How is it possible?
When you leave your home, with the clock stopped, wind the clock and write the time on paper. When he arrives at his friend's house, he writes down the time it is at that moment and when he leaves he remarks it.
When I get home looking at the clock I can know how long he has been away. Subtracting from there the time he had been at his friend's house can calculate what it took to come and go. Adding half of that time to the time it was when he left his friend's house, I could find out the correct time.