Yes; larger bodies do attract more than smaller ones. Do heavy bodies attract with more force than light ones? Yes; heavy bodies do attract more than light ones, although they may be of the same size. Where are all substances drawn by the attraction of gravitation? They are all drawn towards the centre of the earth. Why are substances drawn towards the centre of the earth? Because the earth is larger than any substance on or near its surface. In what direction do all objects fall through the air? They all fall towards the centre of the earth. Which way then do we call “down”? _Down_ is always towards the centre of the earth. Which way do we call “up”? _Up_ is always away from the centre of the earth. Where must all plumb lines or perpendicular lines point? They must all point with one end towards the centre of the earth. When the earth turns over, can any substance fall away from its surface? No; all things are drawn to the earth with so much force that they cannot fall away. Upon what does the weight of a body depend? The weight of a body depends upon the force with which it is drawn towards the earth. What kind of substances are attracted with the most force? Those that are the most dense, like the metals; hence, they are the heaviest. What causes a liquid to form into a drop at the mouth of a bottle? The attraction of cohesion causes the drop to be formed. What causes the drop to fall to the earth? The attraction of gravitation causes the drop to fall to the earth. When water is poured from a tumbler, why does it run down the side of the tumbler? Because the attraction of cohesion draws the water to the side of the tumbler, as is shown in Fig. 27. [Illustration: Fig. 27.] Why does a spout prevent the water from running down the side of the vessel? Because the spout is curved so that its lowest point is where the water falls from it; hence, gravitation causes the water to fall directly to the earth, as is shown in Fig. 28. [Illustration: Fig. 28.] Does the air obstruct bodies when falling through it? Yes; air obstructs all bodies when falling through it; but it obstructs light bodies more than heavy ones. Do all bodies fall with equal rapidity in a vacuum? Yes; all bodies fall with equal rapidity in a vacuum. What bodies fall through the air most rapidly? Those that are the heaviest or most dense; because they are the smallest in bulk. Do heavy bodies increase in velocity as they descend? They do increase rapidly in velocity as they descend. How far does a heavy body like lead fall in one second? It falls sixteen feet in one second. A falling body increases thirty-two feet in velocity for every second of time it is in falling. During the first second it falls sixteen feet. During the second second, it falls sixteen feet plus thirty-two feet, or forty-eight feet. During the third second, it falls forty-eight feet plus thirty-two feet, or eighty feet, etc.