Margules also calculated the work produced when air masses of uniform entropy initially side by side were re-arranged so that they finished on top of one another. The figure below shows an example of a rearrangement where the air masses are initially side by side. Work in the air masses initially side-by-side case is half the work of the air masses initially on top of one another because the side-by-side case is simply an intermediate step. Half as much work is produced because half as much high potential temperature air is raised.