They could all see the black object now, though it looked dim and uncertain, for a fog was settling down over the lake and the mist and vapor, together with the rain, made it hard to see more than a few feet ahead.

“It’s a boat!” suddenly cried Mr. Bobbsey.  “A large boat.”

And that is what it was.

“Ahoy there!” called Captain Craig in his deep voice.  “Ahoy there!”

“Ahoy!” answered the men in the boat.

“Have you seen anything of a runaway balloon?” asked Mr. Trench.  “Mine got away from the Bolton County Fair, and it had two little children in the balloon basket.  Have you seen them?”

Mr. and Mrs. Bobbsey and all in the motor boat waited anxiously for the answer.  Captain Craig had shut off his engine so its noise would not drown the words of those in the other boat.

“We saw something big and black sailing through the air over our heads about an hour ago,” was the answer.  “We thought it was the aeroplane from the fair grounds.”

“That was my balloon!” declared Mr. Trench.

“Did you see anything of my children?” Mrs. Bobbsey begged to know.

“No.  But we couldn’t see very well on account of the fog and because the balloon—­if that’s what it was—­kept up pretty high,” came the answer.

“Which way was she heading?” Captain Craig wanted to know, this being his sailor way of asking which way the balloon was going.

“Due north,” answered one of the men in the other boat, which was a craft containing a number of fishermen.

“Towards Hemlock Island,” stated another.

“Well, we’re going in the right direction,” went on Captain Craig.  “Much obliged,” he called to the fishermen, as the motor-boat again started off through the fog.

Soon the vessel that had been hailed was lost to sight in the mist, and again all eyes, including those of Mr. and Mrs. Bobbsey, were strained in looking for a first sight of Hemlock Island.

“Are you warm enough?” asked Mr. Bobbsey of his wife, wrapping the rubber coat more closely about her.

“Oh, yes.  I’m not thinking of myself,” she answered, with a sigh.  “I am worried about my darlings!”

“I think they’ll come out of it all right,” said her husband.  “Flossie and Freddie, as well as Bert and Nan, have been in many a scrape, but the Bobbsey luck seems to hold good.  They always get out all right.”

“Yes.  And I hope they will this time,” answered Mrs. Bobbsey, trying to appear more cheerful.

For a while they ran along in silence, every one peering out into the rain and the mist striving to catch sight, if not of the balloon, at least of the shore of Hemlock Island.

“My, but this fog is getting thicker and thicker!” exclaimed Captain Craig.  “I’ll have to go a bit slower yet.”

He cut down the speed of the engine until the boat was moving at less than half speed.  But even this did not save her from an accident which came a short time later.