=Example=--If the child is five feet tall and his shadow measures three feet, the shadow is three-fifths of his height. If the shadow of the tree measures fifteen feet, the height of the tree is twenty-five feet. Further Development of Sight There are two important faculties which are dependent upon the operation of the eye for usefulness and accuracy. They are Visualization and Perception. The games which are given later for the improvement of these important mental operations will also develop the sense of sight. It will be better to use these later exercises where double results can be accomplished. Give all the time possible to the games on pages 59 to 69. THE SENSES OF TASTE AND SMELL For most of the mental operations the three senses already treated are the more important ones. There are some trades in which the senses of taste and smell are also important. These can be cultivated readily by exercises of any nature that stimulate an effort on the part of the children. Many ideas will suggest themselves to you from those given for the other senses. It is advisable to do a good deal of the practice blindfolded so as to separate entirely the sense of sight, and force dependence upon the senses of taste and smell. These two senses are very closely allied. Try the experiment of determining the difference in tea, coffee, milk and water while the eyes are covered and the nose held tightly closed. The degree to which these two senses can be developed is illustrated by the proficiency which is shown by experts and testers who grade tea, coffee and tobacco. The usefulness of their development is to a large degree only of value to those engaged in these lines of trade. The opportunity for their development comes rarely except in connection with work in the trades, and for that reason will not be dealt with at any length here. Using Two of the Senses There are times when the ability to use two of the senses with reasonable accuracy at the same time will be of value. It is not possible for either of the senses to produce perfect attention while working in conjunction with one another. We can attend to only one thing at a time and do it well, but "Divided Attention" is possible. Under the chapter on Attention and Concentration, on page 75, you will find an explanation of "Divided Attention," which should be read before going farther with these exercises. Exercises for Two Senses Combine any of the previous exercises for Eye and Ear, Ear and Feeling, Eye and Feeling, etc., but do not attempt two exercises of the same sense or use two of the same order. At first the attention will alternate between the two exercises, but by persistence the child can learn to carry on two exercises at the same time.