“When?” asked Ben.
“Last week. I was cleaning up my desk at the house, and threw away about two hundred of them as useless into the waste basket. Harry picked them up and asked for them.”
“And you gave them to him?”
“That’s it. He said one side was blank, and he liked to carry something with him he could scribble on when he took the fancy.”
“Why, then,” declared Ben, getting very much excited, “that card comes from Harry!”
“It looks that way,” admitted Tom.
“Of course that is it,” insisted Ben. “It’s Harry who has been sending up those balloons.”
“But how could he do that?”
“There’s the mystery, like all the mysteries we’ve been running across lately,” said Ben. “Don’t you see, Tom, he had some writing on the back of those cards?”
“It’s all washed out now.”