"What's the use now? It's all over."
There was a tinkling sound, as fragments of the broken test tube, the bell–jar and other things began falling about the room.
Mark was fumbling at the door of the laboratory, seeking to escape.
"Come on back," said Jack. "It's all over. There's no more danger. We'll try it again."
Just then one of the pile of books, that had been blown on an upper shelf, came down, landing on Mark's head.
"No danger?" cried Mark, trembling from excitement. "No danger? What do you call that?" and he pointed to the books at his feet, while he rubbed his head ruefully.
"Well, there aren't any more," observed Jack, with a look upward.
Just then the door opened, and an elderly gentleman, wearing spectacles, entered the laboratory. He seemed much excited.
"What happened? Is any one hurt? Was there an explosion here?" he asked.
Then he saw the devastation on all sides—the broken glass, the scattered and torn books—and he noticed Mark rubbing his head.