"But animals as well as plants help to fill the air with vapor," continued Fred. "Teacher made us think of a horse drawing a heavy load. You must often have seen a horse at work covered with drops of moisture or sweat. You know that we ourselves cannot work hard or run about without perspiring. We find the sweat drops on our own bodies.
"Now what do you think becomes of all this moisture? I will tell you. It evaporates, and the air absorbs the vapor as it forms.""Oh yes," said Norah, "I have often seen a horse"s body steaming with vapor when he has been working hard.""And not only his body," said Will, "his breath too gives off clouds of vapor. We can see it every time he breathes, and we can see the same thing if we watch our own breath. It is always loaded with vapor."SUMMARY
Most of the vapor in the air is evaporated from the great bodies of water in the hot regions of the world. But some vapor is always rising into the air everywhere. Plants and animals send out vapor into the air.
Lesson 11
Birds and their Beaks
"What do you think of the lions and tigers of the air, Will?" asked Fred one evening.
