The thumb method. Determination of distance
In order to develop a good eye in oneself, one should constantly exercise in determining distances, measure them more often by eye and with the help of calculations, determine the steepness of slopes, the width and speed of a river, etc., for example, when hunting or walking, it’s necessary to mentally determine the distance to any surrounding objects and check it in steps. And the more such tasks the hunter solves, the better. Good, experienced hunters, as is well known, determine the corresponding distances with great accuracy.
Assume that you need to measure the distance to the pedestrian. In this case, you should extend your hand with the raised thumb and close one eye (the right eye closes when the pedestrian moves from right to left). At that moment, when a pedestrian is covered with a finger, you need to close your left eye and open the right one. A pedestrian at the same time seem pushed back.
Now it is necessary to count how many steps a pedestrian will have time to make until the moment when he again covers his finger. The distance to the pedestrian will be equal to the number of steps multiplied by 10. Suppose that he managed to take 16 steps: 16x10 = 160 steps. If at the same time we assume that the step of a person is equal on average to 0.75 m, then to a pedestrian 120 m.