The two main points to remember about stability are these: the wider the base of an object, the harder it is to tip over; and the lower the center of the weight is, the harder it is to tip over. If you were out in a rowboat in a storm, would it be better to sit up straight in the seat or to lie in the bottom of the boat? Why is a flat-bottomed boat safer than a canoe? [Illustration: FIG. 18. Which vase would be the hardest to upset?] Where do you suppose the center of weight of the Leaning Tower of Pisa is,--near the bottom or near the top? _APPLICATION 8._ If you had a large flower to put into a vase and you did not want it to tip over easily, which of the three vases shown in Figure 18 would you choose? _APPLICATION 9._ Some boys made themselves a little sail-boat and went sailing in it. A storm came up. The boat rocked badly and was in danger of tipping over. "Throw out all the heavy things, quick!" shouted one. "No, no, don't for the life of you do it!" called another. "Chop down the mast--here, give me the hatchet!" another one said. "Crouch way down--lie on the bottom." "No, keep moving over to the side that is tipped up!" "Hold the things in the bottom of the boat still, so they'll not keep rolling from side to side." "Jump out and swim!" Every one was shouting at once. Which parts of the advice should you have followed if you had been on board? INFERENCE EXERCISE Explain the following: 21. A ship when it goes to sea always carries ballast (weight) in its bottom. 22. If the ship springs a leak below the water line, the water rushes in. 23. The ship's pumps suck the water up out of the bottom of the ship. 24. The water pours back into the sea from the mouths of the pumps. 25. As the sailors move back and forth on the ship during a storm, they walk with their legs spread far apart. 26. Although the ship tips far from side to side, it rights itself. 27. However far the ship tips, the surface of the water in the bottom stays almost horizontal. 28. While the ship is in danger, the people put on life preservers, which are filled with cork. 29. When the ship rocks violently, people who are standing up are thrown to the floor, but those who are sitting down do not fall over. 30. If the ship fills with water faster than the engines can pump it out, the ship sinks. CHAPTER TWO MOLECULAR ATTRACTION SECTION 6. _How liquids are absorbed: Capillary attraction._ Why do blotters pull water into themselves when a flat piece of glass will not? How does a towel dry your face?