When Daddy Bunker heard about the plan of Russ and Laddie to make a dog-cart, he at first thought the boys could not do it.  
"How are you going to harness Zip to the cart?" he asked.
 
"Oh, we can do it," declared Russ. "We can make a harness out of pieces of rope and some straps¹ in the barn. And we can get a box and put some wheels on it for a cart. It'll be easy."
 
"But maybe Zip won't let himself be hitched² up," said Daddy Bunker. He wanted the boys to have fun while at Grandma Bell's, but he did not want them to go to a lot of work making something, and then be disappointed if it did not work.
 
"Oh, I guess Zip won't mind being harnessed," said Grandma Bell. "Once we had a man working for us who had a small boy. This boy—his name was Bobbie—made a little cart and used to drive Zip hitched to it, and the dog pulled Bobbie all around very nicely."
 
"Did he? Hurray! Then he'll pull us!" shouted Laddie.
 
As soon as Russ and Laddie got back to Grandma Bell's house they began to look for things of which to make the dog-cart and the harness. Two wheels were all they could find, but Daddy Bunker thought they would answer very nicely.
 
"I'll help you make the harness," said Tom Hardy³. "I guess there are enough odd straps around the barn to make a harness for two dogs."
 
Russ and Laddie were glad to hear Tom say this. They felt that making the harness would be the hardest part of the work. The cart would be easier; at least so they hoped.
 
From the grocery store, down at the "Four Corners," where Grandma Bell traded, the boys, the next day, got a fine large soap box. It was quite strong, too.
 
"And it's got to be strong if you boys are going to ride around behind that dog Zip!" said the storekeeper. "He's a goer, Zip is! A goer!"
 
Tom helped the boys fasten the old baby carriage wheels to the box, and also helped them make a pair of shafts⁴, just like those in between which a horse trots⁵, only, of course, the ones for Zip were smaller. The hired man was as good as his word in the matter of a harness, and soon everything was in readiness for the first ride.
 
"The only thing I'm afraid of," said Mother Bunker, "is that Zip won't let himself be harnessed. He may not like it."
 
But the big dog did not seem to mind in the least. He came when Russ called him, and he wagged his tail when the boys showed him the soap-box cart and the harness.
 
"Now we're going to have some fun when you give us a ride!" said Russ, patting Zip's shaggy head.
 
"Bow-wow!" barked the dog, as much as to say:
 
"That's right! We'll have fun!"
 
Daddy Bunker, as well as his wife and Grandma Bell, came out to see how the first trip would turn out. Tom put the harness on Zip. The dog only sniffed⁶ at it and wagged his tail. Perhaps he thought of the time when he had been harnessed this way by Bobbie.
 
"Oh, it's nice! I like it!" cried Mun Bun, when he saw the home-made dog-cart with the baby carriage wheels. "I want a ride now."
 
"So do I," added Margy, who never liked to be left, out of anything in which her smaller brother had a share.
 
"You little folks had better not get in until Russ and Laddie try it," said Mr. Bunker "And they had better keep on the soft grass when they start to drive Zip."
 
"Why should we stay on the grass?" asked Laddie.
 
"So if you fall out of the cart you won't get hurt," his father answered with a merry laugh.
 
"Oh, we won't fall out," declared Russ. "The cart is big enough for two of us."
 
And the soap box was large enough for Russ, Laddie and one more little Bunker, though two made a more comfortable load than three. Tom had nailed in a board for a seat, and really the dog-cart, though rather roughly made, was very nice.
 
"Get in now, and let's see how you go," said Daddy Bunker. He was holding Zip by part of the harness that went around the dog's head. To this, which was a sort of muzzle⁷, there were fastened two pieces of real horse reins⁸, and by these Zip's head could be pulled to the left or the right, according to which way the little drivers wanted him to go.
 
"He guides just like a real horse or a boat," said Laddie. Of course there was no bit in Zip's mouth, as there is in the mouth of a horse, for dogs have to keep their mouth open so much, to cool off when they are hot, that a bit would be in the way.
 
In the soap box Laddie and Russ took their places. Daddy Bunker handed them the lines and let go of the dog's head.
 
"Gid-dap!" called Russ.
 
"Go fast!" ordered Laddie.
 
"Hold tight and don't get spilled out!" begged Mother Bunker.
 
"We will!" promised Laddie.
 
Russ was driving and he didn't feel much like talking just then. He had to give all his attention to Zip.
 
Away trotted⁹ the dog, pulling after him the cart with the two boys in it. Over the grass he went, and when Russ saw that the dog seemed to know just what to do, and didn't show any signs of wanting to turn around and upset the cart, Russ turned his steed toward the path.
 
"We can go faster here, where it isn't so soft," he said.
 
And Zip did pull t............