Rain, Snow, and Hail 113 Ice 116 CHAPTER VI.—Sound. 118 Conduction of Sound 122 Trumpets and Speaking-tubes 125 Velocity of Sound 127 Reflection of Sound 128 CHAPTER VII.—Matter. 131 CHAPTER VIII.—Attraction. 137 Cohesion and Adhesion 137 Capillary Attraction 140 Gravitation 141 Centre of Gravity 145 Specific Gravity 150 CHAPTER IX.—Motion. 154 CHAPTER X.—Mechanical Powers. 164 Lever 164 Wheel and Axle 174 Pulley 176 Inclined Plane 177 Wedge 180 Screw 181 CHAPTER XI.—Electricity. 183 Magnetism 187 Electro-Magnetism 189 FIRST LESSONS IN Natural Philosophy. CHAPTER I. Astronomy. The Earth and Other Planets. [Illustration: Fig. 1.] [Illustration: Illustrated Capital W] What is the shape of the Earth on which we live? It is round like a ball. What other names are given to the Earth? It is called the World or Globe. What else is it sometimes called? It is called a Planet. Are there any other planets? Yes; some of the stars are called planets. Is our earth or world a star? It is a star. Why do the other stars seem to us different from the earth? Because they are so far away from us. What gives light to the planets? The Sun gives light to the planets. Of what is the sun the centre? The sun is the centre of the solar system. Do the planets remain in one place? The planets do not remain in one place, but are always moving. How do the planets move? They move around the sun. Are some planets nearer the sun than others?