"The infamous scoundrel!" exclaimed Duff Salter, looking very dark and serious. "Now, Salter," continued Calvin, "we had a watch set on that ridge of roofs every night, and another one at the old Zane house, front and rear, and the apparition on the roof was so irregular that we could not understand what occasions it took to come out until we observed that whenever your servant was out of the neighborhood a whole night, the roof-walker was sure to descend into Zane's trap." "Jer-i-cho-ho-ho!" "To-night, as we have made ourselves aware, your servant is not in Kensington. We saw him off to Treaty Island. I am watching at this window for the man on the roof. The moment he leaves the trap-door of the tenant's house, it will be entered by officers at the waving of this lamp at my window. One officer will proceed along the roof and station himself on the Zane trap, closing that outlet. At the same time the Zane house will be entered front and rear and searched. The time is due. It is midnight. Come!" Calvin pointed to a ladder that led from the corner of his study to the roof, and Duff Salter nodded his head acquiescently. They went up the ladder and thrust their heads into the soft night of early summer. There was starlight, but no moon. The engine bell just ceased to toll as they looked forth on the scattered suburb, and at points beheld the Delaware flowing darkly, indicated by occasional lights of vessels reflected upward, and by the very distant lamps on the Camden shore. Most of the houses within the range of vision were small, patched, and irregular, except where the black walls of the even blocks on some principal streets strode through. Scarcely a sound, except the tree frogs droning, disturbed the air, and Kensington basked in the midnight like some sleeping village of the plains, stretching out to the fields of cattle and the savory truck farms. Duff Salter mentally exclaimed: "Here, like two angels of good or evil, we spy upon the dull old hamlet, where nothing greater has happened than to-night since the Indians bartered their lands away for things of immediate enjoyment. Are not most of these people Indians still, ready to trade away substantial lands of antique title for the playthings of a few brief hours? Yes, heaven itself was signed away by man and woman for the juices of one forbidden fruit. Here, where the good old pastor, like another William Penn, is running his stakes beyond the stars and peopling with angels his possessions there, the savage children are occupied with the trifles of lust, covetousness, and deceit. They are no worse than the sons of Penn, who became apostates to his charity and religion before the breath had left his body. So goes the human race, whether around the Tree of Knowledge or Kensington's Treaty Tree." Duff Salter felt his arm pulled violently, and heard his companion whisper, "There! Do you see it?"