Worthington Hooker.
CONTENTS.
| CHAPTER | PAGE | |
| I. | AIR | [3009] |
| II. | AIR IN MOTION | [3013] |
| III. | FLYING AND SWIMMING | [3018] |
| IV. | THE PRESSURE OF THE AIR | [3025] |
| V. | PUMPS | [3030] |
| VI. | THE BAROMETER | [3036] |
| VII. | THE AIR-PUMP | [3039] |
| VIII. | GASES | [3044] |
| IX. | POWDER | [3048] |
| X. | POP-GUNS | [3053] |
| XI. | BALLOONS AND BUBBLES | [3057] |
| XII. | MORE ABOUT BALLOONS | [3063] |
| XIII. | HEATED AIR | [3068] |
| XIV. | CHIMNEYS | [3072] |
| XV. | USES OF WATER | [3077] |
| XVI. | WATER ALWAYS TRYING TO BE LEVEL | [3081] |
| XVII. | THE PRESSURE OF WATER | [3087] |
| XVIII. | ATTRACTION IN SOLIDS AND FLUIDS | [3092] |
| XIX. | WATER IN THE AIR | [3097] |
| XX. | CLOUDS | [3101] |
| XXI. | SNOW, FROST, AND ICE | [3105] |
| XXII. | HEAT AND COLD | [3110] |
| XXIII. | THE DIFFUSION OF HEAT | [3114] |
| XXIV. | WHAT HEAT DOES | [3120] |
| XXV. | STEAM | [3125] |
| XXVI. | LIGHT | [3130] |
| XXVII. | COLOR | [3135] |
| XXVIII. | MORE ABOUT COLOR | [3139] |
| XXIX. | ELECTRICITY | [3144] |
| XXX. | MORE ABOUT ELECTRICITY | [3150] |
| XXXI. | MAGNETISM | [3155] |
| XXXII. | GRAVITATION | [3159] |
| XXXIII. | THE MOTION OF THE EARTH | [3165] |
| XXXIV. | FRICTION | [3172] |
| XXXV. | CONCLUSION | [3176] |
CHAPTER I.
AIR.
Air, a thing.
We speak of a room having no furniture in it as being empty; but this is not exactly so. There is one thing that it is full of up to its very top. It is a thing that you can not see; but it is as really a thing as the furniture that you can both see and feel. This thing is air.
If you take all your books out of a box in which you keep them, you think of the box as having nothing in it; but it is full of air; and when you shut it up and put it away, you put away a box full of air. When the books were in it, it was full of books and air together; but now it is full of air alone.