OUR ancestors regarded mountainous regions with feelings of horror, mingled with commiseration for those whom an unkindly destiny had condemned to dwell therein. We, on the other hand, find in the contemplation of the great alps of the Earth such peaceful and elevated thoughts, and such rest to our souls, that it is to those very solitudes we turn to heal the wounds of ife. It is difficult to explain the cause of this very different point of view. It is probably, in part, to be referred to that cloud of superstitious horror which, throughout the Middle Ages, peopled the solitudes with unknown terrors; and, in part, to the asceticism which led the pious to regard the beauty and joy of life as snares to the soul's well-being. In those eternal solitudes where the overwhelming forces of Nature are most in evidence, an evil principle must dwell or a dragon's dreadful brood must find a home. But while in our time the aesthetic aspect of the hills appeals to all, there remains in the physical history of the mountains much that is lost to those who have not shared in the scientific studies of alpine structure and genesis. They lose a past history which for interest com- 116 petes with anything science has to tell of the changes of the Earth. Great as are the physical features of the mountains compared with the works of Man, and great as are the forces involved compared with those we can originate or control, the loftiest ranges are small contrasted with the dimensions of the Earth. It is well to bear this in mind. I give here (Pl. XV.) a measured drawing showing a sector cut from a sphere of 50 cms. radius; so much of it as to exhibit the convergence of its radial boundaries which if prolonged will meet at the centre. On the same scale as the radius the diagram shows the highest mountains and the deepest ocean. The average height of the land and the average depth of the ocean are also exhibited. We see how small a movement of the crust the loftiest elevation of the Himalaya represents and what a little depression holds the ocean. Nevertheless, it is not by any means easy to explain the genesis of those small elevations and depressions. It would lead us far from our immediate subject to discuss the various theoretical views which have been advanced to account for the facts. The idea that mountain folds, and the lesser rugosities of the Earth's surface, arose in a wrinkling of the crust under the influence of cooling and skrinkage of the subcrustal materials, is held by many eminent geologists, but not without dissent from others. The most striking observational fact connected with mountain structure is that, without exception, the ranges 117