I have told you in Part First about the change of color in the leaves in the autumn. All the summer the leaves send the green part of the light to your eyes; but when autumn comes there is some change made in them, so that some kinds of leaves reflect the red part of the light, some the yellow, some the orange, etc.
I have told you about the great variety of colors in the plumage of birds and in the coverings of insects. This variety is all owing to the different ways in which the light is reflected. Some reflect one of the seven colors of the light, and others some other color. Some that reflect all the colors of the light are white, as the swan; and some that reflect none of them look black, as the crow.
Colors of clouds.
Some of the most splendid displays of colors that can be witnessed we occasionally see in the clouds at morning or evening. Now all this is caused by nothing but sunlight and water, for you know that the clouds are made up of water in the shape of fog. The light, as we may say, paints these gorgeous colors upon the drops of water as they hang in the air. The reason that we see these displays of colors in the clouds only at morning and evening is, that the light from the sun strikes them in the right way then. It strikes them in such a way that some of the colors are reflected to our eyes, while others are not. The most common color reflected to our eyes by the clouds is red.
Play of colors in changeable silks, ice, &c.
When and how the rainbow is formed.
You can see in other things that the color of a thing depends on the way in which the light strikes it, and is reflected to your eyes. You see this in the changeable silk. As you move it, the light strikes it differently, and so different colors are reflected to your eyes. When you see the ice scattered on the ground from the trees in winter, shining in the bright sun, you see in one direction all the colors of the rainbow sparkling from the millions of pieces of ice; but if you look in the opposite direction you see none of these colors, but the ice looks white. Why is this? It is because the light on one side of you strikes the ice and is reflected differently from what it is on the other side. And you know that it is not after every thunder-shower that you see a rainbow. The light must strike the rain, and be reflected to your eyes in a particular way, in order to let you see the light divided up in the rain into its seven colors in the bow. You never see a rainbow if the rain is in the same direction with the sun. If the sun is in the west, the rain must be in the east to have the bow form; so that you are between the sun and the rain, with your back to the sun, as you see the bow. Sometimes a rainbow is seen in the morning, when a cloud comes from the east and it clears off by the cloud’s passing to the west. But this seldom happens, and the rainbow is commonly seen in the latter part of the day, the cloud coming from the west and passing off to the east.
Questions.—What is the color of a thing? Does the dyer make color? What does he do? What is said about changeable silk? Mention some other things in which we see the colors change. What is said about the changes of color in different kinds of light? How are the different colors of flowers made? How is it when there are different colors in the same flower? What is said about the shading off of colors? In what sense are the colors of flowers made from the light? And in what sense are they made from the sap? What is said about the change of color in leaves in autumn? What is said about the colors of birds and insects? Tell about the colors of the clouds. Why do we see them at morning and evening? What is said about the way in which light strikes a thing and is reflected to our eyes? Where and in what part of the day do you commonly see the rainbow? Explain this.