As he left the room, Winn noticed that he had a wooden leg.

It was not one of the modern kind, so carefully constructed as to closely resemble the real article, but an old-fashioned, iron-shod stick of timber strapped to his right knee.
As Sabella finished speaking, she too left the room, running after the Captain, and smiling cheerfully as she went at the mud-streaked boy, who still stood speechless and motionless in the doorway.
Now, at Solon's invitation he followed the negro into what had been called the engine-room, though to Winn's eye it looked as little like an engine-room as any place he had ever known.

At one side was a horse-power treadmill, such as he had often seen used for the sawing of wood.

Half of it was sunk below the level of the deck, and covered with a removable floor.

It was geared in the most direct and simple manner to a shaft that disappeared through the rear wall of the room, and presumably connected with the stern wheel he had previously noticed.
There was also a belt extending to a shaft pulley overhead, but beyond this there was no trace of machinery, nor was there either boiler or furnace.