You can be sure these companies of rain-drops, hurrying back to the light, don't fail to notice any cracks in the rocks along the way, and at such places they come gushing up with sparkle and dance; and the greater the dip of the rock beds the higher they dance, of course. But it takes any one rain-drop so long to get back into the sunshine after it starts on its underground journey that you'd think it would forget how to dance at all! It isn't just the same rain-drop, to be sure, that goes into the ground and comes out again, because the rain-drops get all mixed up with each other as they move along, but just imagine some one rain-drop that fell, say, on a hilltop on the day a baby was born in a valley five miles away, where there was a spring in a shady hollow near the baby's home. By the time that rain-drop got down to the spring the baby would be old enough to vote! Yet this is a very good thing for the rivers and the rest of us--this slow travel of the underground water, whether it comes out in springs or simply seeps through the soil as most of that which supplies the rivers does. Otherwise, if all the water of the rains went directly into the rivers we would have floods after every wet spell and empty river beds between times. Here's another river rebus. How do rivers grow longer at the top? All rivers grow at their source because their headwaters eat back into the rocks and the soil, just as the rain wears away the head of any gully. Where the rock is soft they eat back faster. The Mohawk River in New York State probably wouldn't have amounted to anything if it hadn't done this very thing. From Albany westward past Utica runs a belt of shale, a weak stone, but here so soft that the surface of it crumbles back to clay in every winter's frost. Into this the Mohawk, which in past ages was only a little stream, has eaten back its way until now it is over a hundred miles long. But sometimes rivers are so big the very first day they come into the world that you may say they are born half grown. You find them, among other places, in the mountains of California. Nearly all the water from the melting snows on Mount Shasta sinks at once into the porous lava fields of the mountain slopes, and after wandering about in the hidden veins comes out, filtered and cool, in the form of large springs which make rivers that set out on their life journeys without ever having been babies at all so far as you can see. The Shasta River is one of these. The McCloud is another. It gushes forth suddenly from a lava bluff in a roaring spring seventy-five yards across, two-thirds of the width of the river in its widest part. The River Jordan in the Holy Land begins in one of these great springs at the foot of Mount Hermon. [Illustration: _From Norton's "Elements of Geology." By permission of Ginn and Company_ HOW MOST OF EUROPE'S RIVERS GET THEIR START