Sherlock Holmes - Deductions

“Yes, I have been using myself up rather too freely,” he remarked, in answer to my look rather than to my words; “I have been a little pressed of late.”
“What will he do?”
“Engage a special.”

Indeed, if I may make a full confession to you, I was quite convinced that the letter from Meiringen was a hoax, and I allowed you to depart on that errand under the persuasion that some development of this sort would follow.