A paddle steamer is a steamship or steamboat powered by a steam engine that drives paddle wheels to propel the craft through the water. In antiquity, paddle wheelers followed the development of poles, oars and sails, where the first uses were wheelers driven by animals or humans. In the early 19th century, paddle wheels were the predominant way of propulsion for steam-powered boats. In the late 19th century, paddle propulsion was largely superseded by the screw propeller and other marine propulsion systems that have a higher efficiency, especially in rough or open water. Paddle wheels continue to be used by small, pedal-powered paddle boats and by some ships that operate tourist voyages. The latter are often powered by diesel engines. Paddle wheels The paddle wheel is a large steel framework wheel. The outer edge of the wheel is fitted with numerous, regularly spaced paddle blades (called floats or buckets). The bottom quarter or so of the wheel travels under water. An engine rotates the paddle wheel in the water to produce thrust, forward or backward as required. More advanced paddle-wheel designs feature "feathering" methods that keep each paddle blade closer to vertical while in the water to increase efficiency. The upper part of a paddle wheel is normally enclosed in a paddlebox to minimise splashing. Types of paddle steamers The three types of paddle wheel steamer are stern-wheeler, with a single wheel on the rear, a side-wheeler with one on each side, and an inboard with the paddlewheel mounted in a recess amidship. All were used as riverboats in the United States. Some still operate for tourists, for example on the Mississippi River. Stern-wheeler Although the first stern-wheelers were invented in Europe, they saw the most service in North America, especially on the Mississippi River. was built at Brownsville, Pennsylvania, in 1814 as an improvement over the less efficient side-wheelers. The second stern-wheeler built, Washington of 1816, had two decks and served as the prototype for all subsequent steamboats of the Mississippi, including those made famous in Mark Twain's book Life on the Mississippi. Side-wheeler Side-wheelers are used as riverboats and as coastal craft. Though the side wheels and enclosing sponsons make them wider than stern-wheelers, they may be more maneuverable, since they can sometimes move the paddles at different speeds, and even in opposite directions. This extra maneuverability makes side-wheelers popular on the narrower, winding rivers of the Murray–Darling