DEAR SIR,--Pardon me for intruding on you a second time. But, as a friend of virtue, I must warn you of continued danger to your daughter from the acquaintance of Mr. Wilkeson, your pretended benefactor. If you are any longer in doubt as to the vile intentions of this man, conceal yourself from observation within sight of Miss Pillbody's school, any fair afternoon, about half past two o'clock, and watch his actions. If his suspicious conduct, at that time and place, does not give a sufficient significance to my warnings, then take the trouble to go to ----, Westchester Co., where he was born, and search into his infamous history. Take heed--I warn you again--lest, in your devotion to science, you forget that you are a father. ONE WHO WOULD SHIELD THE INNOCENT. While reading this letter, Marcus was conscious that the eyes of the inventor were fixed piercingly upon him. That consciousness caused his head to bow, and his cheeks to crimson with shame. It is the curse of this morbid sensibility, that righteous indignation at a foul slander upon one's good name springs up only after the victim has shown all the accepted evidences of guilt. There was one reason why a man much less sensitive than Marcus should have been thrown off his balance by this letter. It was a fact that every afternoon, at half past two o'clock, rain or shine, with bachelor-like punctuality, he passed up and down in front of Miss Pillbody's school, and looked sentimentally at the closed blinds, thinking unutterable things. He was also addicted to standing at the hydrant on the corner, and gazing hard at the house, wishing that he could see through its brick walls. Then he would cross the street, and pace up and down on that side, taking views of the house at every variety of angle. This was precisely what the boy Bog did daily about an hour and a half later. Now, although Marcus felt, in his heart, that these pedestrian exercises--absurd to everybody but a lover--were perfectly harmless in their purpose and effect, he was aware that, to a man like Mr. Minford, looking at them suspiciously, they would appear to be connected with some stealthy and base design.