Round about cities and large towns there are certainly more people than there are trees, but in many other parts of the world there are a great many more trees than there are people.
I have heard of forests in South America so thick and so large, that the monkeys might run along the tops of the trees for a hundred miles. So you see there are plenty of trees in the world to do the work.
But then, how does all the bad air leave the towns and cities where men live, and get to the forests and meadows?
The air is constantly moving about; rising and falling, sweeping this way or that way, and traveling from place to place.
Not only the little particles out of our breath, but any thing that gives the air any smell, does it some harm. Even nice smells, like those of roses, are unhealthy, if shut up in a room for some time.
Dirty walls, ceilings, and floors give the air a musty, close, smell; so do dirty clothes, muddy boots, cooking, and washing. Some of these ought not to be in the house at all; others remind us to open our windows wide.
All the things I have been saying to you about pure air, apply still more to sick people than to healthy ones.
Directions for Reading.—Read the following sentences carefully, and avoid running the words together.
The good__air can not get__in at__all.