Use the top of a table for your field of operations, and pick out some spot within easy reach of your hand for the target whose range you wish to find. The target may be a penny or a small circle drawn on a piece of white paper. Take a pencil in your hand and imagine it is a shell which you are going to land on the target. It is not quite fair to have a bird's-eye view of the field, so get down on your knees and bring your eyes within a few inches of the top of the table. Now close one eye and making your hand describe an arc through the air, like the arc that a shell would describe, see how nearly you can bring the pencil-point down on the center of the target. Do it slowly, so that your eye may guide the hand throughout its course. You will be surprised to find out how far you come short, or overreach the mark. You will have actually to grope for the target. If by any chance you should score a hit on the first try, you may be sure that it is an accident. Have a friend move the target around to a different position, and try again. Evidently, with one eye you are not a good range-finder; but now use two eyes and you will score a hit every time. Not only can you land the pencil on the penny, but you will be able to bring it down on the very center of the target. The explanation of this is that when you bring your eyes to bear upon any object that is near by, they have to be turned in slightly, so that both of them shall be aimed directly at that object. The nearer the object, the more they are turned in, and the farther the object, the more nearly parallel are the eyes. Long experience has taught you to gage the distance of an object by the feel of the eyes--that is, by the effort your muscles have to make to pull the eyes to a focus--and in this way the eyes give you the range of an object. You do not know what the distance is in feet or inches, but you can tell when the pencil-point has moved out until it is at the same focus as the target. The experiment can be tried on a larger scale with the end of a fishing-rod, but here you will probably have to use a larger target. However, there is a limit to which you can gage the range. At a distance of, say, fifteen or twenty feet, a variation of a few inches beyond or this side of the target makes scarcely any change in the focus of the eyes. That is because the eyes are so close together. If they were farther apart, they could tell the range at much greater distances. SPREADING THE EYES FAR APART