“Good boy!” cried Bert to his dog, as Snap came back to him, wagging his tail, having first made sure, however, that the strange dog was running down the street.  “Good, old Snap!”

And Snap wagged his tail harder than ever, for he liked to be told he had been good and had done something worth while.

“I wonder what that dog wanted?” asked Nan.

“I don’t know,” answered Bert.  “He was a strange one.  But he didn’t stay long!”

“Not with our Snap around!” laughed Nan.

The two older Bobbsey twins were wondering what they could do next to have a good time, when they heard their mother’s voice calling to them from the side porch.  She had come back from a little visit to a lady down the street, and had heard all about the accident to Flossie and Freddie.

“Ho, Nan!  Ho, Bert!  I want you!” called Mrs. Bobbsey.

“I guess she’s going to scold us for making the hay slide on Flossie and Freddie,” said Bert, rather anxiously.

“Well, we couldn’t help it,” replied his sister.  “We didn’t know it was so slippery.  Yes, Mother; we’re coming!” she answered, as Mrs. Bobbsey called again.

But, to the relief of Nan and Bert, their mother did not scold them.  She just said: 

“You must be a little more careful when you’re playing where Flossie and Freddie are.  They are younger than you, and don’t so well know how to look out for themselves.  You must look out for them.  But now I want you to go down to daddy’s office.”

“What do you want us to do?” asked Nan.

“Here is a letter that he ought to have right away,” went on Mrs. Bobbsey.  “It came to the house by mistake.  It should have gone to daddy’s lumber office, but the postman left it while I was out, and Dinah was out in the barn with you children, so she could not tell him to carry it on down town.  So I wish you’d take it to daddy.  He has been expecting it for some time.  It’s about some business, and I don’t want to open the letter and telephone what’s in it.  But if you two will just run down with it—­”

“Of course we will!” cried Bert.  “It’ll be fun!”

“And may we stay a little while?” asked Nan.

“Yes, if you don’t bother daddy.  Here is the letter.”

A little later Nan and Bert were in their father’s office.  The clerks knew the children and smiled at them, and the stenographer, who wrote Mr. Bobbsey’s letters on the clicking typewriter machine, took the twins through her room into their father’s private office.

As the door opened, Bert and Nan saw a strange man talking to Mr. Bobbsey.  But what interested them more than this was the sight of two children—­a boy and a girl about their own age—­in their father’s private office.  The boy and girl were sitting on chairs, looking at the very same lumber books—­those with pictures of big woods in them—­that Nan and Bert often looked at themselves.

Mr. Bobbsey glanced up as the door opened.  He saw his two older twins, and, smiling at them, said: