evidence for various kinds of geological process, the actual operation and rate of progress of which he may thereby be enabled to watch and determine. It may thus be made to throw light upon one of the vexed problems of science--the value of time in geological inquiry. But it is of the relations of such an investigation to human history that I would first more particularly speak. Such inquiries seem to me eminently calculated to engage the sympathies and even the active co-operation of literary students. There can be no doubt that the advancement of our knowledge of the mutations of the land since the beginning of history must depend largely upon help from the study of historical documents. No long series of years has passed since the truth was recognised that man is in large measure the creature of his environment; that his material progress and mental development have been guided and modified by the natural conditions in which he has been placed. The full extent and application of this truth, however, are perhaps not even yet comprehended. If the surrounding and limiting conditions have been such potent factors in human development, we may well believe that any serious change or modification in them cannot but have reacted upon man. If nature alters her aspect to him, either spontaneously on her own part or as the result of human interference with her ways, he too will in some measure be affected thereby, and his relations to her will be influenced. What then have been the kind and amount of the mutations in the face of nature since man first appeared? Although the answer to this question will here be sought in the evidence furnished by Great Britain alone, it will be understood that the principles laid down for the conduct of the inquiry with regard to this country must be of general application to other regions of the globe.