To all appearance, a number of persons had been moving about here, but their foot-prints seemed to lead nowhere, extending simply up and down the wall. What did it mean? Detective Hook had been called upon to solve many mysteries in his time, but never before had he encountered one so deep as this. He was baffled; he could not deny it. Accompanied by the crestfallen Schneider, he repaired to the station at last, and reported the occurrences of the night. In a short space of time every newspaper in the city was preparing for their morning issues an account of the bold robbery of the Webster National Bank. The great clock in Trinity steeple had rang out the hour of four, when Detective Hook, still hovering about the scene of his late defeat, turned, for the twentieth time that night, the corner of Rector street and Broadway. As he did so there brushed past him the figure of a woman, plainly but neatly dressed, with gray hair hanging down from beneath her worsted hood, and wild, roving eyes, moving restlessly from one object to another as she walked along. "Bats in the wall! Bats in the wall!" she muttered, as she passed. "Blessed be the bats in the wall for what they have done for my erring boy this night!" CHAPTER VI. WHAT HAPPENED AT THE CATHERINE MARKET. Of all the quaint old landmarks still standing in the city of New York that serve to remind the more ancient of its inhabitants of the days when they were young, surely none so quaint and curious as the old Catherine Market and its surroundings can be said anywhere to exist. It stood there at the foot of the street whose name it bears when the writer was a boy--and many long years before--and will, no doubt, stand there long after he is dead and gone, a low, narrow shed of rotten wood, in color a dingy brown, with three half-round windows on the ferry side--we mean the ones over the oyster booth, where they used to give a round dozen saddle-rocks to every stew, and over the coffee and cake saloon, where the butter-cakes were always fresh on the pan--looking like the eyes of some great monster standing majestically alone in the center of the little square, calmly watching the crowds that pour out of the ferry-gates as the sun rises up, and pour in again as it goes down. Now there is nothing stylish about the Catherine Market, nothing in any way smacking of "tone." It is not one-third the size of the Washington Market, nor does it profess to have that far-famed celebrity for succulent meats, fat turtle, fish, oysters and clams to which Fulton Market lays claim. But it does a driving, thriving business of its own, just the same, does the Catherine Market--make no mistake about that! For here come to purchase their daily supplies the denizens of Water, Cherry and Oliver streets, of Madison, Monroe and Hamilton streets, to say nothing of East Broadway, equal in number, when taken all in all, to the population of a good-sized city in themselves.