But what's the matter now? All of a sudden they stop singing and begin to shout and fire off their guns. You'll laugh when I tell you why. They heard something talking back to them; repeating all their words. It was only an echo made by the rocks of the mountains that we have just reached. But these superstitious people of the desert don't know what an echo is. They think echoes are the voices of evil spirits mocking them, and the shouting and the firing of the guns is to frighten these mockers away. [Illustration: THE PACK-RAT'S FORTRESS This is a diagram of the fortress of another little citizen of mountain rocks and desert places, known out West as the "pack" rat because he is always packing off other people's things and hiding them in his burrow. The "fortress" consists of several burrows, the roads leading to which are carefully protected by the prickly bayonets of the cactus joints which the rat drags there for that purpose. ] Life for everybody in the Sahara and the Arabian desert is very much what it is for the animals in the Arizona wastes--a constant struggle for food. In the Arizona desert every living creature puts in all its time trying to get something to eat without being eaten. The wildcat is fortunate if he gets a meal once in two or three days; and while the coyote is trying to slip up on a rabbit, ten to one there's a panther slipping up on him. A traveller in northern Africa tells how, when his caravan halted for dinner at an inn for the French soldiers quartered in that region, he saw a lean and hungry cat eying him from around the corner of a nearby hut. To borrow from Victor Hugo's description of the hungry cat at the Spanish inn,[31] this cat of the desert looked at the traveller "as if it would have asked nothing better than to be a tiger." When the guest of the inn had finished the piece of chicken he was eating he tossed the bone toward the cat which pounced on it fiercely. Instantly a dog, which had been watching proceedings, rushed forward and took the bone from the cat. Just then an Arab, who happened to be passing, fell upon the dog and wrenching the bone from his mouth began eagerly gnawing it himself. [Footnote 31: "Hugo's Letters to His Wife."] It's a hard life! And yet if you should bring an Arab boy to London or New York to live and give him three good meals a day--he's not always sure of _one_ at home--and nice clothes to wear and a real bed to sleep in, and shady parks to play in, do you suppose he would be happy? No indeed. The thing has been tried. He says this kind of life is all right for those who like it, but it _isn't_ the desert. And you have to admit it! HIDE AND SEEK IN THE LIBRARY Not at all dry, are they--these deserts--when you get down into them? And I haven't told you half there is to tell about them.[32] [Footnote 32: John C. Van Dyke, for one, has written a wonderfully interesting little book just about the American desert. It's called simply "The Desert."]