Monday morning came, after Sunday (as it always does if you wait long enough) and the two sets of Bobbsey twins started for school.

"I wish we didn't have to go," said Bert, as he strapped up his books. "I want to go down to our new houseboat."

"But you must go to school," said his mother with a smile. "There will not be many more days now. June will soon be over, and you know school closes a little earlier than usual this year. So run along, like good children."

Off they hurried and soon they were mingling with their boy and girl friends, who were also on their way to their classes.

"You can't guess what we're going to have," said Freddie to a boy named Johnnie Wilson, who was in his room.

"Kittens?" asked Johnnie.

"No."

"Puppies?"

"No."

"I give up--what is it?"

"A houseboat," said Freddie. "It's a house on a boat, and you can live in it on water."

"Huh!" said Johnnie. "There isn't any such thing."

"Yes, there is, too, isn't there, Flossie?" and Freddie appealed to his small sister.

"'Course there is," she said. "Our papa bought one, and Freddie's going to be the fireman, and I'm going to cook the meals, so there! Haven't we got a houseboat, Nan?"

"Yes, dear," answered the older sister, who was walking with Bert. At this, coming from Nan, Johnnie had nothing to say, except that he murmured, as he walked away:

"Huh! A houseboat's nothing. We've got a baby at our house, and it's got hair on its head, and two teeth!"

"A houseboat's better'n a baby," was Freddie's opinion.

"It is not!" cried Johnnie.

"It is so!" Freddie exclaimed.

"Hush!" begged Nan. "Please don't dispute. Houseboats and babies are both nice. But now it's time to go to school."

The Bobbsey twins could hardly wait for the classes to be out that day, for their mother had promised to call for them after lessons, and, with their father, they were going to see the Bluebird. The houseboat had been brought up the lake by Mr. Marvin, and tied to a dock not far from Mr. Bobbsey's lumber office. The boat was now the property of Mr. Bobbsey, but that gentleman had not yet fully planned what he would do with her.

Just as the children were trooping out of the school yard, along came Mrs. Bobbsey. Nan and Flossie saw their mother and hastened toward her, while Freddie and Bert came along more slowly.

In a little while all five of them were at Mr. Bobbsey's lumber office. He came out of his private room, when one of his clerks told him Mrs. Bobbsey and the children were there.

"Ah, what can I do for you to-day?" asked Mr. Bobbsey of his wife, just like Mr. Fitch, the grocery-store-keeper. "Would you like a barrel of sawdust, ma'am; or a bundle of shingles to fry for the children's suppers?" and Mr. Bobbsey pretended he was no relation to his family.

"I think we'll have a houseboat," said his wife with a laugh. "Have you time to take us down to it? I can't do a thing with these children, they are so anxious to see the Bluebird." "Well, I hope they'll like her," said Mr. Bobbsey, "and not pull any feathers out of her tail."

"Oh, is there a real bird on the boat?" asked Flossie.

"No, papa is only joking," said Nan, with a smile.

Mr. Bobbsey put on his hat, and soon the whole Bobbsey family had reached the place where the boat was tied. At the first sight of her, with her pretty blue paint and white trimming, Nan cried:

"Oh, how lovely!"

"And how big it is!" exclaimed Freddie his eyes large and round with wonder.

"Let's go aboard--where's the gang-plank?" asked Bert, trying to use some boat language he had heard from his father's lumbermen.

The Bluebird was indeed a fine, large houseboat, roomy and comfortable. The children went inside, and, after looking around the main, or living room, and peering into the dining-room, Nan opened the door of a smaller compartment. Inside she saw a cunning little bed.

"Oh, may I have this room?" she asked. "Isn't it sweet!"

"Here's another just like it," said Mrs. Bobbsey, opening the next door.

"That will be mine," said Flossie.

"My room's going to be back here, by the engine," spoke Bert, as he picked out his sleeping place.

"And I'll come with you," said Freddie. "I'm going to be fireman!" Gleefully the children were running about, clapping their hands, and finding something new and strange every minute.

"Where is your room, mamma?" asked Nan. "We ought to have let you and papa have first choice."

"Oh, there are plenty of rooms," said Mr. Bobbsey. "Let's go up on deck and---"

He stopped suddenly, and seemed to be listening.

"What is it?" asked his wife.

"There seems to be some one on this boat beside ourselves," answered Mr. Bobbsey. "I'll go look."

CHAPTER V

THE STRANGE BOY

The Bobbsey twins looked at one another, and then at their mother, as Mr. Bobbsey went out of the living room of the houseboat, toward the stairway that led up on deck.

Bert tried to look brave, and as though he did not care. Nan moved a little closer to her mother. As for Flossie, she, too, was a little frightened, but Freddie did not seem at all alarmed.

"Is it somebody come to take the boat away from us?" he asked in his high-pitched, childish voice. "If it is--don't let 'em, papa."

They all laughed at this--even Mr. Bobbsey, and he turned to look around, half way up the stairs, saying:

"No, Freddie, I won't let them take our boat."

"Pooh! Just as if they could--it's ours!" spoke Bert.

"Who could it be on board here, mamma?" asked Nan.

"I don't know, dear, unless it was some one passing through the lumber yard, who stopped to see what the boat looked like," answered Mrs. Bobbsey. "Papa will soon find out."

The noise they had heard was the footsteps of some one walking about on the deck of the houseboat.

"Perhaps it was one of the men from the office, who came to tell papa he was wanted up there, or that some one wanted to speak to him on the telephone," went on Mrs. Bobbsey. She saw that the children, even Bert, were a little alarmed, for the boat was tied at a lonely place in the lumber yard, and tramps frequently had to be driven away from the piles of boards under which there were a number of good places to sleep.

Mr. Bobbsey did not mean to be unkind to the poor men who had no homes, but tramps often smoke, and are not careful about their matches. There had been one or two fires in the lumber yard, and Mr. Bobbsey did not want any more blazes.

Soon the footsteps of the children's father were heard on the deck above them, and, a little later Freddie and the others could hear the talk of two persons.

"I guess it was one of the men," said Mrs. Bobbsey.

"I'm going to see," spoke Bert, and he moved toward the stairway, followed by Nan, Flossie and Freddie. They went up on deck and saw their father talking to a strange boy. None of the Bobbsey children knew him.

"Are you looking for some one?" asked Mr. Bobbsey kindly, of the strange boy. Often, when he was in distant parts of the lumber yard, and he was wanted at the office, or telephone, his men might ask some boy to run and tell the owner of the yard he was needed. But Mr. Bobbsey had never seen this lad before.

"No, sir, I--I wasn't looking for any one," said the boy, as he looked down at his shoes, which were full of holes, and put his hands into the pockets of his trousers, which were quite ragged. "I was just