What earthly reason was there for keeping from her only son a knowledge of the fact that _L’Oiseau_ was her brother-in-law, and that her abnormal physical and mental condition required these unusual and suspicious attentions from him? Again, _L’Oiseau_ was rambling about at night with _Mrs. Quillmore_ when she lost consciousness, fell by the wayside, was found by the priest, and succored by _Doc. Gus_. What had become of her escort, _L’Oiseau_? He had mysteriously disappeared, and _Doc. Gus_ had a right to put the worst construction upon his conduct. _Father Lessing_ knew the truth; why did _Father Lessing_ allow _Doc. Gus_ to remain in ignorance? But the most serious blunder in the plot relates to the climax—the fire in _Colonel Quillmore’s_ laboratory. _Doc. Gus_ sees the shadow of two men thrown upon the window shade. Only one of these men is accounted for, and the reader is left not only in doubt as to what happened, but in hopeless confusion. He cannot adopt any theory which will explain _all the facts_. Now, _that_ is against the rules. Let the plot be ever so complicated, the mystery ever so deep, the author _must_ either clear it up himself, or furnish the reader with the clue. Wilkie Collins, in spite of his bewildering tangles, unravels everything before he quits. In “Edwin Drood,” the book which Dickens was writing when death interrupted the story, the author had constructed one of his most involved and difficult plots. Before he had furnished the key to the riddle, he died. Yet Edgar Allan Poe was able to tell, with unerring certainty, just how the story was meant to end. By a keen analysis of the facts which Dickens had already related, and by a course of reasoning that left no room for doubt, Poe demonstrated that _Jasper_, the guardian and devoted friend of _Edwin Drood_, had murdered him; that jealousy was the motive; that the body of the victim was hidden in the new tomb which the inflated ass, _Sapsea_, had recently built for the deceased _Mrs. Sapsea_; and that the corpse was located by old _Durdles_, the drunken workman whose skill with his hammer was so great that he could, by tapping, tapping, tapping on the outside or a wall, tell whether a foreign substance, such as a human body, was inclosed within. Poe’s own matchless story, “The Gold Bug,” illustrates the rule which Mr. Chatterton broke. There are all sorts of mystifications to start with, but they are cleared up at the end. Even in Frank Stockton’s famous “The Lady or the Tiger,” the rule is kept. The reader is left in a dilemma, but he can clear up everything by choosing one horn or the other. If he says that it is the lady who is behind the door which is about to be opened, no mystery remains. If he says that it is the tiger which is behind the door, nothing is left of the puzzle.