Thank you for the input regarding the C.S.S. Arkansas, Alan. A direct-acting steam engine provides its motive power directly to a shaft without an intermediary shaft or lever. Paddle wheel boats needed the lever as a force-multiplyer due to the great area of the paddles, Ericsson also used them on his engines for screw propulsion. "Precedents for Steam" by Benjamin Isherwood, Chief Engineer, U.S.N. is available online through Google books.