The best time to do this would be in the spring, because then the kingdom of the glaciers is most beautiful, and the spirit of a glorious new world, just waking up, is abroad everywhere. The glaciers themselves seem to feel so good about it that they start to sing. And like the birds, their joyous springtime mood responds to the quick changes of sun and shade. In our own land when the sky grows cloudy, even for a short time as you may have noticed, birds stop singing. Then when the sky clears they start up again. But, up here in the Alps in the spring when the birds are singing among the mountain meadows, the glaciers, at whose feet these meadows lie, do the very same thing. The songs of the birds are various, and the song of the same bird will differ at different times of day, but the song of the glacier is always the same--a pleasant dreamy tune between the murmur of little voices and the tinkle of distant bells. The very rocks that the glacier carries on its back seem to catch the spirit of the springtime; for, when the weather is bright, they go strolling. And when they do they remind us a little of that painting by Franz Hals, "The Laughing Cavalier," for they apparently wear a big broad-brimmed hat cocked jauntily on one side. [Illustration: UP WHERE THE GLACIERS GROW Here we are, looking down on the roof of the Alps--from a flying-machine, let us say. The sky-line used to be more like the ridge of a house, straight across. In the course of the ages the glaciers and the weather have cut down the softer rock, leaving those peaks. At the top are the snow-fields. Farther down the glaciers begin to form. Still farther down, where the glaciers have begun to melt, you can see a stream--its waters have taken white in the picture because of the foam and the ground-up rock in it called "rock flour"--falling into the woods below, the "timber line" of your geography. Ruskin has a wonderful word-picture of these mountain streams in his "Modern Painters." The index of any edition will tell you where. ] THE MAN WHO DISCOVERED THE ICE AGE