"All right, Marie," she said. Then she glanced at the bottle and the glasses on the table; not quite the proper fittings for a chat with the government. "I'll see them in the study."

She rose and started from the room. Then suddenly she heard a small scraping noise and turned back quickly. For a moment she stood still, staring at the table. Could the bottle actually have been moving just as she turned around? But of course that was silly.

Just nerves, she told herself, and continued into the hallway.

After introductions, Julie led the men to the study, gave them seats and took a place opposite them. She would have known they were from the government even if she hadn't been told; with that careful, unrevealing look, they only needed an official stamp of certification on their foreheads.

"Is there something I can do for you?" she asked.

"Well, we're not exactly sure," one of the men said. "However, we have reason to believe you can." He cleared his throat. "To get directly to the point, we are interested in an explosion which we believe took place on these premises last night."

"Oh, dear!" Julie said. "Have the neighbors complained?"

"No, Mrs. Pillsworth, nothing like that. You see, we have mechanical means of knowing about explosions. There is a device in existence which records the precise time, location, magnitude and nature of even the slightest explosion anywhere on the Earth's surface. One was recorded here last night. The nature, however, was undetermined and that's why we decided to investigate."

Julie nodded. She told them of Marc's basement laboratory and his experiments to make heavy substances lighter than air. She explained about the explosion.

"The experiment was a complete failure, I guess," she concluded.