CHAPTER. PAGE. I. How many pounds the whole earth weighs. 3 II. The attempt to weigh the earth. 5 III. Description of the experiment to weigh the earth. 8 PART II. VELOCITY. I. Velocities of the forces of nature. 13 II. How can the velocity of the electric current be ascertained. 15 PART III. NUTRITION. I. Nothing but milk. 21 II. Man the transformed food. 24 III. What strange food we eat. 26 IV. How nature prepares our food. 29 V. What becomes of the mother's milk after it has entered the body of the child. 32 VI. How the blood becomes the vital part of the body. 35 VII. The circulation of matter. 38 VIII. Food. 41 IX. About nutrition. 44 PART IV. LIGHT AND DISTANCE. I. Something about illumination. 49 II. The illumination of the planets by the sun. 52 PART V. THE WONDERS OF ASTRONOMY. I. A wonderful discovery. 57 II. The main support of Leverrier's discovery. 60 III. The great discovery. 63 PART VI. METEOROLOGY. I. Something about the weather. 69 II. Of the weather in summer and winter. 73 III. The currents of air and the weather. 75 IV. The firm rules of meteorology. 78 V. Air and water in their relations to weather. 81 VI. Fog, clouds, rain, and snow. 84 VII. How heat in the air becomes latent, and how it gets free again. 87 VIII. Latent heat produces cold, free heat produces warmth. 90 IX. Rules about the weather, and disturbances of the same. 93 X. The changeableness of the weather with regard to our geographical position. 96 XI. About the difficulty and possibility of determining the weather. 98 XII. The false-weather prophets. 101 XIII. Has the moon influence upon the weather? 103 PART VII. OUR ARTICLES OF FOOD.