[13] Britannica.
[14] International.
Another famous river over in that part of the world—it's the biggest river in Western Asia, in fact—was born twins. See if you can find such a river on the map. (The name of it is at the end of the next chapter.) In the days of Alexander the Great these twin rivers, which now unite in one after travelling along independently for a while, were a good day's journey apart clear to the end. In the article on this river in the Britannica, and in books of travel you will find how, by a quaint and ingenious device, the river is made to pump itself up hill and irrigate the fields; how history, clear back to the beginning of civilization, is written in the ruins of cities along its banks; how it used to put in part of its time bounding the Roman empire, and how nowadays it is forced to help support Arab river pirates and wild pigs.
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.)
[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;