Of course, the boulders, like other people, differ in their tastes--as you can tell by their talk. The granite boulders have the most to say about travel because they are so hard that they can take longer journeys than weaker rocks, and so have more to tell. But there is another branch of the family that is still more "bookish" as you may say. These are the "pudding stone" boulders--conglomerates. In that most interesting biography, "The Story of a Boulder," Professor Geikie describes a stone that was not only made up of a variety of pebbles, but in which there was a section of sandstone. The sandstone and the conglomerate had been neighbors in some rock ledge just as the pebble section and the smooth sand section are always neighbors where the shores descend into the sea. So when the rock mass, which was finally rounded into a boulder, broke away it included portions of both sandstone and conglomerate. [Illustration: WHERE THE SEA HELPS SHAPE THE BOULDERS] The upper part of this boulder--the sandstone--had in it stems and leaflets of plants of the Coal Age, changed to coal. The pebbles below were fragments of more ancient rocks made at a time when frogs as big as the oxen of to-day lived in the marshes. "They must have had a croak like a fog-horn," said the High School Boy. In this story of the boulder, Professor Geikie says: "I had here a quaint old black letter volume of the Middle Ages giving an account of the events taking place at the time it was written and containing in its earlier pages numerous quotations from the authors of antiquity." [Illustration: WHICH DO YOU SAY?] The "quotations from the authors of antiquity," were the pebbles, of course, once parts of older rocks. I have spoken of the boulders as authors. You will also be interested in their relations with artists. Boulders add much to the picturesque effect of the shores of lakes and seas and mountain ravines, as they appear to the traveller, and as artists reproduce them in pictures. They also add to the beauty of streams, by forming rapids. These boulders that are piled in so thick as to make rapids are brought in by smaller but swifter tributaries that flow into larger but more sluggish streams. Rapids are favorite topics for landscape artists. They are characteristic of the work of Ruysdael, for example, with whom you have become well acquainted in your picture studies in school. Of the drawing of stones in general Ruskin says: "There are no natural objects out of which an artist, or any one who appreciates the form of things, can learn more than out of stones. A stone is a mountain in miniature. The fineness of Nature's work is so great that into a single block a foot or two in diameter she can compass as many changes of form and structure on a small scale as she needs for her mountains on a large one, using moss for forests and grains of crystal for crags."[27] [Footnote 27: "Modern Painters."] [Illustration: WHY BOULDERS SOMETIMES TAKE A JUMP