"This can't go on, you know," the latter said tersely.
"Of course it can't," Hackness replied. "All the air is getting exhausted. Come with me down to Scotland Yard and help to try and persuade Williamson to test my experiment."
"What! Do you mean to say he is still obstinate?"
"Well, perhaps he feels different to-day. Come along."
Williamson was in a chastened frame of mind. He had no optimistic words when Hackness suggested that nothing less than a violent meteorological disturbance would clear the deadly peril of the fog away. It was time for drastic remedies, and if they failed things would be no worse than before.
"But can you manage it?" Williamson asked.
"I fancy so," Hackness replied. "It's a risk, of course, but everything has been ready for a long time. We could start after to-morrow midnight, or any time for that matter."
"Very well," Williamson sighed with the air of a man who realises that after all the tooth must come out. "If this produces a calamity I shall be asked to send in my resignation. If I refuse——"
"If you refuse there is more than a chance that you won't want another situation," Hackness said grimly. "Let's get the thing going, Eldred."
They crawled along through the black suffocating darkness, feeble, languid, and sweating at every pore. There was a murky closeness in the vitiated atmosphere that seemed to take all the strength and energy away. At any other time the walk to Clarence Terrace would have been a pleasure, now it was a penance. They found their objective after a deal of patience and trouble. Hackness yelled in the doorway. There was a sound of footsteps and Cynthia Grimfern spoke.