The essential function of agriculture is to produce consumable commodities and hence it is necessary to turn from land use and attempt to determine spatial variations in productivity and production in the arable realm during the July Monarchy. In order to be intelligible, patterns of production must be related to patterns of consumption and to the spatial variations in commodity prices which characterised the country prior to its effective integration by the railway network. Such matters are clearly fundamental in attempting to determine the relative efficiency of agricultural activity throughout the country, however contemporaries wrote little about them and they have received only slight attention from recent scholars. Michel Morineau demonstrated the superiority of wheat and rye yields in Nord département and the broad contrast between high- and low-yielding areas on either side of a line between Les Sables-d'Olonne and Lake Geneva. 1 Admittedly wheat and rye formed the major sources of bread grain but the other cereals deserve scrutiny in order to discover if spatial variations in their productivity conformed to the patterns produced for the leading grains or whether individual crops produced their own discrete patterns in relation to the particular ecological conditions to which they were best suited.