“I—I was taking the pay-roll from the bank when some—something happened. I—I saw a hand. I heard a voice, and—and then I must have had some sort of sinking spell.”

“Same old story,” Tom said in a low tone to Jimmie.

“The Bubble Man,” Jimmie said.

“What’s that?” Jimmie made no reply.

“Tom,” Jimmie gripped his arm, “will they mind if I sort of brush around the floor?”

“Who? They?” Tom nodded at the officers. “No, I guess not. But why——”

“Don’t ask me. I’ll explain later.” Dropping on hands and knees the boy began brushing the floor in a wide circle. He used Tom’s clothes brush. When at last his circle had narrowed to a spot the size of a man’s hat he placed a single square of newspaper on the polished floor of the subway and appeared to brush an invisible something onto the paper. Truth was, his arduous brushing appeared to have caught only three insignificant bits of paper, one of them a fragment of a chewing gum wrapper.

“There,” he sighed, as, having folded the bit of newspaper neatly, then wrapped it in another square, he thrust it into his pocket.

Tom was too busy asking questions, examining the victim’s clothing and looking for possible clues to pay any attention to his actions.

When at last they walked out into the street, Tom said,