As seen through the face of a window clock, Mirsad Muhic of Boylan Marble & Terrazzo Restoration, an Oneida, N.Y., company, rode a scrubber on the terrazzo floor of the Science Museum's rotunda yesterday. The museum removed the linoleum in the rotunda area to reveal the floor from the early 20th century, when the building was a train station. The dark, elongated areas are where benches were positioned.