The largest and most powerful locomotives in the world are those being built for the Pittsburg, Bessemer & Lake Erie Railroad for hauling long trains of iron and ore, one of which has just been completed. Its cylinders are 24 × 32 inches; drive wheels, 54 inches diameter; weight, 125 tons; draw bar pull 56,300 pounds, and hauling capacity 7,847 tons. One of these mammoth engines is capable of drawing a train of box cars, loaded with wheat, and more than a mile long, at a speed of ten miles an hour. This load of wheat would represent the yield of 14 square miles of land. No doubt it would greatly astonish our forefathers to know that at the end of the century we would have iron horses capable of carting away, at a single load, the products of 14 square miles of the country side, and do it at a gait faster than that of their local mail coach. CHAPTER XII. STEAM NAVIGATION. EARLY EXPERIMENTS--SYMINGTON’S BOAT--COL. JOHN STEVENS’ SCREW PROPELLER--ROBT. FULTON AND THE “CLERMONT”--FIRST TRIP TO SEA BY STEVENS’ “PHŒNIX”--“SAVANNAH,” THE FIRST STEAM VESSEL TO CROSS THE OCEAN--ERICSSON’S SCREW PROPELLER--THE “GREAT EASTERN”--THE WHALEBACK STEAMERS--OCEAN GREYHOUNDS--THE “OCEANIC,” LARGEST STEAMSHIP IN THE WORLD--THE “TURBINIA”--FULTON’S “DEMOLOGOS,” FIRST WAR VESSEL--THE TURRET MONITOR--MODERN BATTLESHIPS AND TORPEDO BOATS--HOLLAND SUBMARINE BOAT. The application of steam for the propulsion of boats engaged the attention of inventors along with the very earliest development of the steam engine itself. Blasco de Garay in 1543, the Marquis of Worcester in 1655, Savary in 1698, Denys Papin in 1707, Dr. John Allen in 1730, Jonathan Hulls in 1737, Bernouilli and Genevois in 1757, William Henry (of Pennsylvania) in 1763, Count D’Auxiron and M. Perier in 1774, the Marquis de Jouffroy in 1781, James Rumsey (on the Potomac) in 1782, Benjamin Franklin and Oliver Evans in 1786 and 1789, John Fitch in 1786, and also again in 1796, and William Symington in 1788-89 were the early experimenters. Papin’s boat was said to have been used on the Fulda at Cassel, and was reported to have been destroyed by bargemen, who feared that it would deprive them of a livelihood. Allen, Rumsey, Franklin, and Evans (1786) proposed to employ a backwardly discharged column of water issuing from a pump. Jonathan Hulls and Oliver Evans (1789) had stern wheels. Bernouilli, Genevois, and the Marquis de Jouffroy used paddles on the duck’s foot principle, which closed when dragged forward, and expanded when pushed to the rear. Fitch’s first boat employed a system of paddles suspended by their handles from cranks, which, in revolving, gave the paddles a motion simulating that which the Indian imparts to his paddle. Symington’s boat of 1788 (Patrick Miller’s pleasure boat) had side paddle wheels. Symington’s next boat, built in 1789, and also owned by Patrick Miller, was of the catamaran type, _i. e._, it had two