"He's gone off after the balloon. Flossie and Freddie are in it," Nan answered.
"Whew! Those little children taking a balloon ride!" cried Bob. "How did they dare?"
"It was an accident," Harry explained. "They didn't mean to."
"Well, tell your father I want to see him when he gets back," said Bob, as he hurried back to the merry-go-round. "I have something to tell him about Mr. Blipper."
However, Bert and Nan had other things to think about then than about Mr. Blipper. They were worried over what might happen to Flossie and Freddie.
Meanwhile, Mr. and Mrs. Bobbsey were hastening toward the lake. Mr. Bobbsey drove his car as fast as he dared through the storm. It was now raining hard.
"How long would the balloon stay up in the air?" asked Mr. Bobbsey of Mr. Trench.
"It all depends. On a hot day, when the sun warms the gas, it would stay up a long time. But when it is cool, like this, and rains, it will not stay up so long. It will come down gently, and I am sure the children will not be hurt."
As they drove along they stopped now and then to ask people if they had seen the runaway balloon. Many had, and all said it was sailing toward the lake.
When the lake was reached and a motor-boat had been found which would take them out on the water, several men said they had seen the big gas bag beginning to go down near Hemlock Island, the largest island in the lake.