Radial, tangential, and cross-sections of 350 North American woods from the 14-volume rare book The American Woods, published between 1888 and 1910 by the author, Romeyn Beck Hough. The images can be accessed by volume number or by the scientific or common name of each tree.
http://www.lib.ncsu.edu/specialcollections/forestry/hough/index.html
http://www.lib.ncsu.edu/specialcollections/forestry/hough/index.html