The studies of Gilliéron and his followers in linguistic geography have made us familiar with the doctrine that two words of different origin which become homonyms by regular sound-changes may interfere with one another to such an extent that one is ultimately excluded from the vocabulary of a given dialect. The lack of a linguistic atlas of England has prevented the application of this principle, and likewise of others expounded by Gilliéron, to English dialects. For it was the comparison of maps which enabled Gilliéron and Roques to show, for example, that only in those French dialects where mulgere would have become homonymous with molere, is it replaced by other words for ‘milk’, such as tirer, traire, ajuster, aria, blechi, etc. Although neat demonstration of this sort is seldom possible in English, conclusions about the conflict of homonyms may sometimes be reached, in the absence of an atlas, by more roundabout methods. Enough information for reasonable deductions may be obtained from the combined materials of the English Dialect Dictionary, which gives the distribution of a large part of the vocabulary in modern dialects, and the New English Dictionary, which gives a detailed semantic history and the approximate time of a word's disappearance from the language.