"Round up," is what cowboys call riding around a lot of horses or cattle to keep the animals in one place or to drive them where they should go. Uncle Frank wanted his cowboys to ride after the runaway ponies and drive them back into the corral.
As the wild little horses trotted out through the gate, behind which Trouble stood, well out of danger, the cowboys rode after them, yelling and shouting and shooting their revolvers.
"What a lot of noise!" cried Janet, covering her ears with her hands as she got down off the fence.
"I like it!" laughed Teddy. "It's like a Wild West show!"
Indeed it was, in a way, but it meant a lot of work for Uncle Frank and his men. For all the ponies ran out of the corral and were scattering over the prairie.
"Oh, Trouble! did you let the horses out?" asked Janet, as her little brother came out from behind the gate and toddled toward her and Ted. The runaway horses were now well out of the way. "Did you open the gate?"
"Yes. I did open gate," Trouble answered, smiling.
"What for?" asked Teddy.
"Help little horses get out," said Trouble. "Them want to get out and Trouble help them. Trouble 'ike ponies!"
"Oh, but, my dear, you shouldn't have done it!" chided Mother Martin, who had come out of the house to find out what all the excitement was about. "That was very naughty of you. See all the work you have made for Uncle Frank and his men."