Drawing comparing M.1844 8-inch columbiad and M. 1861 10-inch "Rodman" columbiad.
Albert Manucy
<p>ARTILLERY THROUGH THE AGES
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A Short Illustrated History of Cannon, Emphasizing Types Used in America <a rel="nofollow" class="external free" href="http://www.nps.gov/history/history/online_books/source/is3/is3toc.htm">http://www.nps.gov/history/history/online_books/source/is3/is3toc.htm</a>