'Economic Geometry': Marshall's and Other Early Representations of Demand and Supply

Does an apparent (minor) anomaly, said to occur not infrequently in elementary expositions of supply and demand theory, really imply – as seems to be suggested – that there is something a bit odd about Marshall’s diagrammatic handling of demand and supply? On investigation, we find some interesting differences of focus and exposition amongst the theorists who first developed the ‘geometric’ treatment of demand and supply, but find no reason, despite his differences from other marginalist pioneers such as Cournot, Dupuit and Walras, to consider Marshall’s treatment either as unconventional or forced, or as to regard him as the ‘odd man out’.