Murchison remained for many years an opponent of the glacial theory in its larger application. In the discourse to which the above letter makes allusion (Address at the Anniversary Meeting of the Geological Society of London, 1842.* (* Extract from Report in volume 33 of the "Edinburgh New Philosophical Journal".)) is this passage: "Once grant to Agassiz that his deepest valleys of Switzerland, such as the enormous Lake of Geneva, were formerly filled with snow and ice, and I see no stopping place. From that hypothesis you may proceed to fill the Baltic and the northern seas, cover southern England and half of Germany and Russia with similar icy sheets, on the surfaces of which all the northern boulders might have been shot off. So long as the greater number of the practical geologists of Europe are opposed to the wide extension of a terrestrial glacial theory, there can be little risk that such a doctrine should take too deep a hold of the mind. . . The existence of glaciers in Scotland and England (I mean in the Alpine sense) is not, at all events, established to the satisfaction of what I believe to be by far the greater number of British geologists." Twenty years later, with rare candor, Murchison wrote to Agassiz as follows; by its connection, though not by its date, the extract is in place here: "I send you my last anniversary address, which I wrote entirely myself; and I beg you to believe that in the part of it that refers to the glacial period, and to Europe as it was geographically, I have had the sincerest pleasure in avowing that I was wrong in opposing as I did your grand and original idea of my native mountains. Yes! I am now convinced that glaciers did descend from the mountains to the plains as they do now in Greenland." During the summer of 1842, at about the same date with Murchison's letter disclaiming the glacial theory, Agassiz received, on the other hand, a new evidence, and one which must have given him especial pleasure, of the favorable impression his views were making in some quarters in England. FROM DR. BUCKLAND. OXFORD, July 22, 1842. You will, I am sure, rejoice with me at the adhesion of C. Darwin to the doctrine of ancient glaciers in North Wales, of which I send you a copy, and which was communicated to me by Dr. Tritten, during the late meeting at Manchester, in time to be quoted by me versus Murchison, when he was proclaiming the exclusive agency of floating icebergs in drifting erratic blocks and making scratched and polished surfaces. It has raised the glacial theory fifty per cent, as far as relates to glaciers descending inclined valleys; but Hopkins and the Cantabrigians are still as obstinate as ever against allowing the power of expansion to move ice along great distances on horizontal surfaces. . . The following is the letter referred to above. C. DARWIN TO DR. TRITTEN.