"He smiles into the Hayloft dim, and the brown hay smiles back at him."
An example of an arch is a curved opening in a doorway. In order to remain intact, the two halves of the arch need to have an equal amount of tension between them at all times so it doesn't collapse. This is the meaning of the proverb, an arch never sleeps.
This is a math question, but it's okay. 24 minutes is when they're tied because that's the least common denominator. Since the first runner is 6, I think being tied is the most he will get.