eleven o'clock
You do n't even need the extra trouble of putting on evening dress in my house . ' ` How very fortunate , ' said Merton , and in a quarter of an hour he was attired as a simple citizen , and was driving to the house of Mr. Macnab . Here he was merely introduced to the guests -- it was a men 's party -- as a gentleman from England on business . The guests had too much tact to tarry long , and by eleven o'clock the chief and Merton were ringing at the door bell of Professor Lumley . The servant knew both of them , and ushered them into the professor 's study . He was reading examination papers . Mrs. Lumley had not returned from a party .