"And could we see the Potomac River?" Bert wanted to know.

"Surely!" laughed Billy's father. "I'll show you all the sights of Washington if you'll come and pay me a visit--all you Bobbsey twins!" he added.

"I wish we could go!" sighed Nan.

"Perhaps you can," said her father.

"Have you got any hay in Wash'ton?" asked Freddie, suddenly, and every one else laughed except himself and Flossie.

"Oh, I guess I could find enough hay for you and your little sister to hide under," answered Mr. Martin with a laugh, for he had heard the story of what had happened in the barn.

A little later Mr. Martin and his boy and girl had to leave. They said "good-bye," and while the father of the Washington children again asked Mr. and Mrs. Bobbsey to come to visit him at his home, Nell and Billy whispered to Nan and Bert:

"Be sure and come, and bring Flossie and Freddie with you!"

"We will!" promised Nan, but neither she nor Bert guessed what a queer little adventure they were soon to have in Washington.

A few days later school opened, and the Bobbsey twins had to go back to their cla.s.s-rooms. At first they did not like it, after the long, joyous vacation on the deep, blue sea, but their teachers were kind, and finally the twins began to feel that, after all, school was not such a bad place.

Thanksgiving Day came, bringing a little vacation period, and after church in the morning, the Bobbsey twins went home to eat roast turkey and cranberry sauce. Then they went out to play with some of their boy and girl friends, having lots of fun in the barn and yard.

"But don't slide any more hay down on Flossie and Freddie!" begged Mrs.

Bobbsey.

"We won't!" promised Bert and Nan, and they kept their word.

It was about a week after Thanksgiving, and Bert and Nan were on their way home from school one day, when, as they pa.s.sed a red brick house on the street next to theirs, they saw, standing on the porch, a pleasant-faced, elderly lady who was looking up and down the avenue.

"That's Miss Pompret," said Nan to Bert. "I heard mother say she was very rich."

"Is she?" asked Bert. "She looks kind of funny."

"That's 'cause she isn't married," returned Nan. "Some folks call her an old maid, but I don't think she's very old, even if her hair is white.

Her face looks nice."

"Yes, but she looks kind of worried now," said Bert. "That's the way mother looks when she's worried."

They were in front of the house now, and could see Miss Pompret quite plainly. Certainly the elderly lady did look as though something troubled her.

"Good afternoon, Miss Pompret!" called Nan, as she was about to pa.s.s by.

Bert took off his cap and bowed.

"Oh, you're half of the Bobbsey twins, aren't you?" asked Miss Pompret, with a smile. "I often see you go past. I only wish you were a little bigger."

"Bigger? Why?" asked Bert, in some surprise.

"Why, then," explained Miss Pompret, "you might take this letter to the post-office for me. It's very important, and I want it to go out on this mail, but I can't go to the post-office myself. If you Bobbsey twins were bigger I should ask you to take it. Tell me, is the other set of twins larger than you two?"

"No'm; they're smaller," explained Nan. "Flossie and Freddie are lots littler than we are."

"But we're big enough to take the letter to the post-office for you, Miss Pompret," said Bert. He had often heard his father and mother speak of this neighbor, and the kindnesses she had done.

"Are you sure you are big enough to go to the post-office for me?" asked Miss Pompret.

"We often go for daddy and mother," said Nan.

"Well, then, if you think your mother wouldn't mind, I would like, very much, to have you go," said Miss Pompret. "The letter is very important, but I can not take it myself, as I have company, and I have no one, just now, who can leave. I thought I might see some large boy on the street, but--"

"I'm big enough!" exclaimed Bert.

"Yes, I believe you are!" agreed the elderly lady, looking at him through her gla.s.ses. "Well, I shall be very thankful to you and your sister if you will mail the letter for me. And, on your way back, stop and let me know that you dropped it in the post-office all right."

"We will!" promised Bert, and Nan nodded her head in agreement with him.

Miss Pompret handed over the letter, which was in a large envelope. Nan and Bert were soon at the post-office with it.

The white-haired lady was waiting for them on the porch as they came back along the street.

"Won't you come in, just for a minute?" she asked, smiling kindly at them. "My maid has just baked a chocolate cake, and I don't believe your mother would mind if you each had a piece."

"Oh, no'm--she wouldn't mind at all!" said Bert quickly.

"We like chocolate cake," said Nan, "but we didn't go to the post-office for that!"

"Bless your heart, child, I know you didn't!" laughed their new friend.

"Please come in!"

The chocolate cake was all Bert and Nan hoped it would be, and besides that Miss Pompret set out on the table for them each a gla.s.s of milk.

They looked around the beautiful but old-fashioned room, noting the dark mahogany furniture, the cut gla.s.s on the side-board, and, over in one corner, a gla.s.s cupboard, through the clear doors of which could be seen some china dishes.

Miss Pompret saw Nan looking at this set of china, and the elderly lady smiled as she said:

"Isn't it beautiful?"

"Yes," said Nan, softly. "I love pretty dishes."

"And these are my greatest treasure," said Miss Pompret. "I am very proud of them. They have been in my family over a hundred years. But there is a sad story about it--a very sad story about the old Pompret china." And the lady's face clouded.

"Did somebody break it?" asked Bert. Once he had broken a plate of which his mother was very proud, and he remembered how sad she felt.

"No, my china wasn't broken," said Miss Pompret. "In fact, there is a sort of mystery about it."

"Oh, please tell me!" begged Nan. "I like nice dishes and I like stories."

She and Bert looked at the closet of choice china dishes. Children though they were, they could see that the plates, cups, saucers and other dishes were not like the kind set on their table every day.

What could Miss Pompret mean about a "mystery" connected with her set of china?