masses of rock incessantly, or to any great extent, must be unhesitatingly rejected as being opposed to reason and to facts.[1] However, "confining the action of glaciers to the simple rubbing away of the rocks, and allowing them sufficient time to act, it is not a matter of opinion, but a physical certainty, that they" would produce cavities or depressions of one sort or another. Given eternity, glaciers might even grind out valleys of a peculiar kind. Such valleys would bear remarkably little resemblance to the valleys of the Alps. They might be interesting, but they would be miserably unpicturesque. The hob-nailed boots of the Alpine tourists would be useless in them; we should have to employ felt slippers or skates.
I have advanced only a few of the more obvious objections to Dr. Tyndall's theory. Many others might be urged, for the position taken up by the Doctor has been from the first an essentially false one, and has permitted him to be attacked from nearly every direction. Had he confined himself to stating that glaciers were competent to excavate valleys, without offering examples, and without attempting to show how they would do it, many persons might have differed from him, but would have done so chiefly in degree. The declaration that the valleys of the Alps had been so excavated was a statement of a much more advanced and of a much graver nature, and I cannot but think that in making it Dr. Tyndall has materially retarded the progress of knowledge. There are many persons, I am convinced, who would learn with satisfaction that he repudiates a doctrine which can be disproved in a multitude of ways, and which is flatly contradicted by a host of facts.
Whatever may be the popular opinion about Professor Ramsay's theory regarding the formation of rock-basins, its author is entitled to credit for having attempted to grapple with an acknowledged difficulty, and to be congratulated upon the number of valu-
