Arthur felt that his father was committing a crime against him.
When he saw Adelaide and his mother their anxious looks made him furious.
So! They knew how helpless he was; they were pitying him.

_Pitying_ him! Pitying _him_! He just tasted his coffee; with scowling brow he hastened to the stables for his saddle horse and rode away alone.

"Wait a few minutes and I'll come with you," called Adelaide from the porch as he galloped by.

He pretended not to hear.

When clear of the town he "took it out" on his horse, using whip and spur until it gripped the bit and ran away.