Scotch Marine Boilers
The Scotch Marine Boiler is a fire-tube boiler, in that hot flue gases pass through tubes set within a tank of water. The general layout is that of a squat horizontal cylinder. One or more large cylindrical furnaces are in the lower part of the boiler shell. Above this is a large number of small-diameter fire-tubes. Gases and smoke from the furnace pass to the back of the boiler, then return through the small tubes and up and out of the chimney.