room too-but that may be only a pretense just to make it look as if they had a fire.

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The books are something like our books only the words go the wrong way; I know that because I've held up one of our books to the glass, and then they hold up one in the other room.

"Oh Kitty, how nice it would be if we could get through into Looking-Glass House! I'm sure it's got-oh such beautiful things in it! Let's pretend the glass has got all soft like gauze. Why, it's turning into a sort of mist now, I declare"

She was up on the mantel when she said this, though she hardly knew how she got there.

In another moment Alice was through the glass and had jumped lightly down into the looking-glass room.

LEWIS CARROLL.

It takes a whole book to tell Alice's adventures in Looking-Glass World, for she went further than the house she had been so anxious to see. When the quest ended the story says she waked.

"You waked me out of oh such a nice dream!" she said, “and you've been along with me, Kitty, all through Looking-Glass World."

Image making is different from "bending" or "dividing," but it includes both of them. It makes a

IN LOOKING-GLASS WORLD

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colored photograph without using a camera, and if the subject is alive the image seems to be alive.

How strange it seems that one's image should face the other way! Yet when we know about reflected light it would be stranger if it did not. What if it

were also upside down?

What a pity that the mirror cannot keep some of its image-pictures. But, on the other hand, mirrors are too costly for a single using. Is it not wonderful that so many images can come and go leaving no telltale trace?

Try some experiments for yourselves. Walk toward the image and see it walk to you. Baby Ned had to learn that it was himself and not another boy. You know it so well that you have forgotten when and how you found it out.

Have you ever thought that you never saw your real faces, but only the image faces that reflected light gives you?

XVIII. HEAT STORIES

THE behavior of Heat when it comes to the earth is nearly as interesting as that of its sister Light.

Both are daughters of the Sun. It is said that Earth dimly remembers a time when she herself was a great ball of fire and light. That was before there was any such earth as we know about. Deep down in her heart she is still terribly hot.

Vesuvius and Etna, volcanoes in Italy, and Mont Pelee, which has worked such dire disaster in our own time, keep the story from being forgotten, and boiling springs tell the same about the center of the earth.

Light comes to us through the wonderful gateway of sight. Its entrance windows are our eyes. Heat coming by the same rays makes itself known through touch and feeling.

Heat is a true fairy,-gentle, obedient, kindly, helpful, comforting; but, like many fairies or things without human souls, just as likely to be fierce, cruel, destructive, deadly.

It needs to be understood and to have a master. Taken so, it is obedient and useful.

HEAT STORIES

How much do we know about its ways?

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Entering a room, noiselessly and invisibly, it fills every part, doing what it can. It moves in little waves in the air. This is called radiation.

Some things receive it readily and hold it well, and some are very slow to take it. You can find out what these things are. In Book Two we had the story how heat gets stored in plants and shrubs, and waits till it is needed for man's use.

Wood and coal, oil and gas, alcohol, and a great many other things have heat imprisoned. These substances are food for fire, which delights to set the heat fairies free. Setting heat free is called burning or combustion, whether you see a flame or not.

Paper and light cloth have but a little heat, and they let it go in bright flame the moment fire touches them; a bed of coal has its heat locked up so tightly that it takes a strong fire to get hold of it, but it has greater strength when it does get hold, and will work through piece after piece till every part has breathed out its strong breath and left nothing but a bed of cinders.

Fire catches hold of gas and alcohol more readily even than of cloth or paper, and the breath they give out is fiercer than that of coal. You know through

what tiny tubes they are allowed to come into touch with anything that will set them free, or, as people say, ignite them.

It is safe for you to make some experiments with heat that is not ignited. You can hold an iron poker and a wooden stick with one end on the top of a hot stove and see in which heat comes first to your hands. Put things made of iron, tin, aluminum, nickel, earthenware, soapstone, etc., on the stove or in the sun, and see which gets hot soonest; then take them. and watch the cooling again.

away

Water and mercury are convenient heat measurers. At so many degrees (32) water freezes, and at so many (212) it changes to vapor.

Mercury is a liquid at ordinary temperature. It takes a cold of 40° below zero to freeze it. By means of a thermometer (thermo, heat; meter, measure) its least change can be measured. The mercury expands when the heat is increased and needs more room. Because it fills the bulb and has nowhere else to go it rises in the tube. Then a scale on the frame of the thermometer registers the changes of heat. It is not so safe to play with fire.

tells some of the dangers.

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