Engineering--Problems, exercises, etc 2 Science and Engineering--Notes 2 Science and engineering--Pennsylvania--Philadelphia--20th century 2 Bessemer process 1 Business--History--Pennsylvania--Philadelphia--20th century 1 Clubs and Associations--Philadelphia--20th century 1 Engineering--Pennsylvania--Philadelphia 1 more ... Engineers--19th century 1 Engineers--Pennsylvania--Philadelphia--19th century 1 Philadelphia (Pa.)--History--20th century 1 Railroad engineering 1 Steel 1 Steel--Standards--United States 1 United States--History--Civil War, 1861-1865--New Orleans, Battle of, 1862 1 United States--History--Civil War, 1861-1865--Personal Correspondence 1 Voyages and travels 1 World War, 1939-1945--Personal narratives, American 1 less ...