"I'll tell him," promised Bob Guess.
"Now let's go see the balloon," suggested Bert.
"They're getting ready to send it up!" exclaimed Harry, as they neared the place where the big bag, already partly filled with gas, was swaying to and fro. Over the bag was a net work of strong cords, and the cords were fastened to the rim of a large square basket. To the basket were tied ropes, and to the ends of these ropes were bags of sand, thus holding the balloon to the ground.
"What makes it go up?" asked Flossie, as she watched the swaying bag.
"Gas," explained Mr. Bobbsey. "They put in the big bag some gas, sometimes one kind and sometimes another, just like the gas in your toy balloons. This gas is so very light—it's not even so heavy as air—that it wants to go up into the air, all by itself. And when it is inside a bag the gas takes the bag up into the air with it."
"And the basket too? Doesn't it take the basket?" Freddie asked.
"Yes, the basket goes up with the balloon," said Mrs. Bobbsey.
"Who goes in the basket?" asked Freddie.
"Oh, the man," his father answered.
"Do any children go in the balloon?" called out Flossie. "Any boys or girls?"