Allan, . J.N.  FOUR TRACK VIADUCT OVER HARLEM FLATS BETWEEN 98TH AND 112TH STREETS NEW YORK CITY.  NY: J.N. Allan, nd (1870s). Steel engraving, 6.75" x 4.5" image on a 10.25" x 7.5" sheet.  A couple light mounting tape marks on the top edge of the back, but a clean and attractive print. Suitable for research or display. Very good.