Now let's go over into Africa with Doctor Livingstone and see how a river can grind out a big, deep stone jar in solid rock.[15] Rivers grind out these _pot-holes_ much as Indian women and the American pioneers used to grind wheat and corn. (The river, you'll find, uses pebbles for millstones.) [Footnote 15: "The Expedition to the Zambesi," page 63. One of these natural water-jars that Doctor Livingstone found was as wide as a well and so deep it kept the water cool even under the broiling African sun.] And what do you think of a waterfall big enough to swallow two Niagaras? (It's the greatest waterfall in the world; so you must have learned its name in your geography.) It's described on page 268 of Doctor Livingstone's book referred to in the foot-note. The natives call it "The Fall of the Thundering Smoke." They wonder how water can smoke, and so that you can see the "smoke" twenty miles away. You'll wonder, too, until you learn the reason. CHAPTER V (MAY) When April steps aside for May, Like diamonds all the rain-drops glisten; Fresh violets open every day; To some new bird each hour we listen. --_Lucy Larcom._ THE FAIRYLAND OF CHANGE What a wonderful world it is, this world of green fields and perfume and blossoms of pink and gold! Where did it come from? How did it get here out of the white winter? That bleak and barren winter that lay all around us everywhere only a few short weeks ago? Just suppose we had never seen apple trees in bloom, as we are now seeing them everywhere, and somebody should show us a little brown seed, and a piece of bark, and a piece of root, and a green leaf, and a blossom, and an apple, and tell us they grew out of each other--were all made of the very same stuff. Well, just as sure as anything, you wouldn't believe it. I wouldn't believe it. We simply couldn't! But we've had this sort of thing all around us ever since we can remember, and we've got so used to it we don't see anything wonderful about it. It _is_ wonderful just the same. The Colossus of Rhodes, and Jupiter of Olympia, and the lighthouse of Alexandria, and all the other Seven Wonders of the World that people used to go so far to see, weren't anything to it. And to this day, how it all comes about is as much of a mystery as ever. Yet Nature does it right before our eyes, and over and over and over again! Even I, old as I am, and as much as I know, _I_ don't know how she does it, but I do know how it all started; how Nature first began to change one thing into another. It was when she began making marbles, granites, and other kinds of rock out of other kinds. That was ages before she changed little brown seeds into big trees with pink blossoms and red apples on them, or little brown cocoons into big golden butterflies, or anything like that. I. In the Fairyland of Change