“Cudgel your brains, my good fellow! this is very important. Did he make no allusion to his engagement to marry Miss Silvester at Craig Fernie? Didn’t he try to pacify her by an apology of some sort?”

The question roused Arnold’s memory to make another effort.

“Yes,” he answered. “Geoffrey said something about being true to his engagement, or keeping his promise or words to that effect.”

“You’re sure of what you say now?”

“I am certain of it.”

Sir Patrick made another note.

“Was the letter signed?” he asked, when he had done.

“Yes.”

“And dated?”

“Yes.” Arnold’s memory made a second effort, after he had given his second affirmative answer. “Wait a little,” he said. “I remember something else about the letter. It was not only dated. The time of day at which it was written was put as well.”