Hildegarde paused in the door and turned. “I can’t ask you to pardon him,” she said. “I shall come again.” Then she preceded her father through the door.

Cantor closed it and smiled grimly. “You need have no anxiety over Miss von Essen,” he said.

Potter shook his head. “That gets me,” he said. “How do you do it, Cantor? In another minute I’d have had to thrash that old bounder.... I’m much obliged for the miracle.”

“He needs a little taking down,” Cantor said, contemptuously. “These rich German-Americans get too cocky sometimes. They have to be shown.”

“I’d like to have your formula,” said Potter.

Cantor changed the subject. “How’s the motor coming?”

“Slowly.”

“I haven’t seen the drawings,” Cantor suggested. “I’m interested, you know.”

“I’d like to show them to you,” Potter replied, “but I’m not showing them to anybody. I feel as if it were government work, you know. I’m sure you’ll understand.”

“Perfectly. I shouldn’t have suggested it.... Just dropped in to ask you to come down to the club to dinner to-night.”