If you look near the tops of some of the older surviving buildings downtown, you might still see cast iron brackets with pieces of mirrors at about the third floor level with the letters "NYV" worked into the bracket's design. This was a remnant of an experiment in surveillance from Police Chief Louis P. Booker, who took over the department a few years after the police riots. The idea was to replace policemen walking the beat with a system of mirrors and telescopes. The letters "NYV" stood for New York Vigilance. Radiating from the old police building on Centre Street and carefully aligned in their brackets, views of all major "crime ridden" intersections were projected into a darkened observation room deep in the center of the building. Details of suspicious activity could be examined directly on screens made of translucent mica with the aid of magnifying glasses. A small team of deaf mutes was hired to lip read conversations - when justified by a legally obtained warrant, of course!
Unfortunately, the mirrors were an easy target for schoolboys, who took to heaving newly laid Belgian blocks at the precisely placed mirrors. And speaking of "newly laid," the observation room was drawn into scandal as muckraking journalists revealed its secondary purpose as a trysting spot.[where: Broome St. and Centre St. New York City, NY]