Blair Bridge  Longitudinal Section of Caisson
Railroad Bridge -- Missouri River  Blair, Nebraska

Photocopy from George S. Morison's The Blair Crossing Bridge 1886. 
Library of Congress    HAER, NEB,89-BLAIR.V,1-4                                      Internet Scan                           Catalog No. BGR-0004
http://memory.loc.gov/pnp/habshaer/ne/ne0000/ne0057/photos/103679pv.jpg