In any scheme of stream ordering, the order assigned to a given stream segment depends on the scale of the map used to make the drainage basin analysis, since new forkings at the headwaters may become observable as the map scale is increased. If one new set of forkings becomes observable, the Strahler orders increase by one; the consistent (“logarithmic”) scheme of orders recently proposed by Scheidegger changes values in varying amounts depending on the topology of the newly observable streams.