He drove away with a laugh, while the Bobbsey twins gathered about the mysterious box in the hall—a box that had come to their father on the eve of his birthday.

What was in it?

That is what each of the Bobbsey twins wondered.

CHAPTER II

QUEER NOISES

“What is going on down there, my dears?” called Mrs. Bobbsey from the top of the stairs. Down in the hall below she could see, gathered about the mysterious box, the four twins. She had heard the bell ring, and at first thought it was her husband, coming home early on account of the birthday celebration.

But when she heard the strange tones of the expressman she realized that something else had happened, and she was curious to know what it was about.

“It’s a big box for Daddy,” explained Bert.

“We don’t know where it’s from,” went on Nan.

“And the ’spress man didn’t know what was in it,” added Flossie.