Now, do you understand about oxygen and nitrogen, which chiefly make up the atmospheric air?" "I know that oxygen made the wire burn beautifully, and I know that horrid nitrogen killed the poor little mouse; but I don't half believe that they are in the air I breathe. I like to see pretty experiments, but I do hate explanations. Now will you let me fly a kite?" "Yes; come out into the open air--remember it is composed of oxygen and nitrogen--and I'll make you a kite." So saying, she led him into the gardens, and waving her wand over a piece of birch bark, behold three splendid kites! The larger one resembled an eagle, and as it mounted into the air, and its light wings flapped in the wind, it seemed about to pounce upon the two smaller kites, which were in shape like pigeons. Rudolph was enchanted, and clapped his hands with glee. After allowing him to enjoy the novelty for some time, the Fairy said to him, "To-morrow I will show you another kite, more wonderful than these. I will make it so, that it will draw down the electricity from the sky. Have you ever rubbed a cat's fur the wrong way, in the dark?" "Oh, that I have! it's great fun. There's our black cat, at home, I have often done it to her, and I can see the sparks in cold weather." "Well, that is electricity, and there is electricity in every thing, only some objects have more than others. When you see the sparks, it is the electricity leaving a thing which is overcharged with it, for another which has less, to keep up a balance. The lightning is nothing but electricity, and to-morrow I'll make a storm, to show you how to draw down this subtle element from the clouds." "Oh, don't trouble yourself! I like this kind of kite well enough: if I have to learn about that old electricity, I'd rather give up playing kite." "Rudolph, would you like to play at soap-bubbles?" "That I would! How I wish Bertha was here--wouldn't she clap her hands and jump, as the large bubbles fly up into the air!" "I do not wish you to think about little Bertha. Here are your basin of soapsuds and your golden pipe; now blow away, my boy!" "Oh, how very pretty! Do you see that big fellow, how he shines in the sun, and shows all the colors of the rainbow? Isn't it fine?" "That is the very thing I want to tell you about. The sun, shining upon vapor and falling water, makes all these beautiful colors. That is the way I mix the rainbow. The science which teaches about the rays of light, their reflection and refraction, and the coloring they give to different objects, is called Optics: it is an interesting study, and I wish you to be a proficient in it." "Optics, is it? That seems to me very different from blowing soap-bubbles. I do hate to be cheated into learning big words, and understanding things, when I am playing."