If a carpenter is hammering nails into the wall, or if a shoemaker is sewing leather to make a shoe, it does not matter very much how the light falls, because his work is so big that he can see it well enough in any part of the room; but if a man is writing a lecture, or if a boy is studying his lessons, it makes very much difference where the light comes from. People who use books and pens every day have to be especially careful about the way the light shines on their work. Look around your school-room and see where the light is brightest. Every house gets its light either from daylight through the windows—which is the very best to use—or from lamps, gas, or electricity; but whichever kind of light it is, the way it slants toward our book or our work is a matter of great importance to the eyes themselves.

Take a book, stand with your back toward the window, and try to read. Your shadow falls all over the page and makes it almost as bad for your eyes as if you were in a dark room.

Now turn squarely around and face the window. This is uncomfortable, too; because if you hold the book slanting upward, as you ought to do, the page is in the shadow again, while the bright light is in your eyes. Of course this is as wrong as possible. Try again.

Stand with your right side toward the window. This is quite fine, you think; the light is on the page and your eyes are in the shadow. Yes, that is very well for reading; but if you were writing, the shadow of your hand would fall across the page and bother you a little. Put your hand up as if you were writing on the page, and see what I mean.

There is just one other way. Stand with your left side to the window. Now everything is perfect for reading and for writing too. The light shines on the white page; it is reflected up to your eyes and you see the words easily. You do not face the light, and if you are writing, the shadow of the hand falls where it does not cover anything.

Whatever kind of light is in the room, the rule about the right way to sit is always the same. Desks should never face the window, and blackboards ought to be opposite the windows and not between them. This not only saves the eyes from being dazzled but makes it easier to read what is written. Notice all these points for yourself.

You should never strain your eyes; that is, everything you read in the schoolroom should be easy to see.

Write a sentence on your slate. Write the same sentence on paper with your pen. The last one is so much easier to read that we know at once that it is the best for the eyes. Ink should always be jet black, even when it is first put on paper. Blackboards and slates should be clean that the writing may show plainly. Dim marks hurt the eyes. The easier it is to see a thing the better it is for the eyesight. This is just as true of books and newspapers as of blackboards and writing paper.

Here is a newspaper. I pick it up from the table and I notice several interesting points about it. Some of the letters are large and some are small some of the lines are near together and some are far apart some of them are short and some are long. On the first page of this special paper there are seven columns and most of the letters are no larger than these in this book. On the second page, however, there is but one column. It is a monstrous advertisement with large letters and lines far apart.

I learn from all this that when the letters are small and the lines near together it is best not to have long lines. In fact, the smaller the letters are the shorter the lines ought to be. Notice the length of the lines on this page. How many words do you find in each line?

It is easy to see that if the page you are reading were as wide as a newspaper, if the letters were small, if the lines were packed together closely, and if they stretched across the whole page from one side to the other, it would be hard for the eye to jump back from the end of one line to the beginning of the next. With large letters, therefore, each line may be much longer than when the letters are small.

People who print books usually think of these things. They use white paper and black ink; they do not crowd the lines together; they leave a good margin around the edge of the page; they do everything that will help the eyes and save them from doing hard work when they use books.

If you wish to make a little examination of your own eyes you may use the newspaper again in a different way. Pin it to the side of the room and step as far from it as will let you see the large letters easily. Read with both eyes first. Now read with one eye at a time. While you are using one eye leave the other one wide open, but cover it with something black or with your hand.

If you find that you can read better with one eye than you can with the other, there is some trouble and your father should take you to the oculist. Probably you need glasses.

When you read this page, if you do not see each line and each letter distinctly, or if you have a tired feeling in the eyes, you should tell your father or your teacher.

We call people nearsighted when they have to hold their books very near to the eyes to read; we call them farsighted when they have to hold them too far away. Neither kind of sight is quite right. If you have to hold this book nearer to your eyes than twelve inches, or farther off than seventeen inches, you may need glasses. The oculist will tell you.

Many children need glasses for a few years only and are able to go without them as they grow older; whereas if they do not have them when they need them, they suffer later. For this reason, if you have any trouble, your father should take you to the oculist once or twice a year.