He asked Donovan to come and show him his horse, as he must see it before thinking of exchanging.

They proceeded to the paddock together.

The horse was standing under a tree, tired-looking.
Dad stood and looked at Donovan for fully half-a-minute without speaking.
"Why, damn it!" he exclaimed, at last, "that's MY OWN horse...You don't mean...S'help me! Old Bess's foal!" Donovan told him he was making a mistake.
"Mistake be hanged!" replied Dad, walking round the animal.

"Not much of a mistake about HIM!" Just here Dave appeared, as was proper.
"Do you know this horse ?" Dad asked him.

"Yes, of course," he answered, surprisedly, with his eyes open wide, "Bess's foal!--of course it is." "There you are!" said Dad, grinning triumphantly.
Donovan seemed uneasy.
Joe in his turn appeared.