5:30
`` Did he leave any word as to when he would come in ? '' `` Yes , sir . He said that a gentleman might call , and to say that he certainly would be back at six , and would not go out again to-night . '' Mr. Smith looked at his watch -- it was 5:30 . Had there been any uncertainty as to Livingstone 's return , he would have waited . But it was clear that he was coming back to dine at his hotel , and to spend the evening there . A note , therefore , could be trusted to do the business , and by writing , instead of waiting , Mr. Smith would save half an hour ; moreover , if he waited , he would not have time to make the mayonnaise .