Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: PART I. HOME GEOGRAPHY. CHAPTER III. SAND MODELLING IN ELEMENTARY GEOGRAPHY. The study of relief has given rise to many devices for aiding the imagination to picture the surfaces of the continents. Maps made of papier-mache, layers of cardboard or leather, stamped paper, carved wood, putty, clay, plaster of Paris, and various glue and whiting mixtures have been used with success; but the device best known and most extensively used is sand modelling. The excellent results obtained from this natural language of form seem to insure its general adoption. Before discussing its practical value in the schoolroom, it may be well to consider the laws that condition the development of form perception. Although psychologists and physiologists may differ widely as to the perception of extension or the first and second dimensions, by sight, binocular vision, touch, or the muscular sense, they agree that the original sense of solid form or the third dimension is touch or rather the muscular sense of grasp, just as that of color is sight, and of sound, hearing. Sensations of roughness, sharpness, roundness, surfaceslope, relief and the like are occasioned by touch primarily. But from early childhood, in seeing and feeling objects at the same time, we have learned to associate the light and shade perceived upon an object with the sensation of touch, and thus acquired the faculty of judging of form by sight. For example, we feel carefully the surface of a ball, occasioning the sensation of roundness. At the same time, we perceive the gradual blending of light and shade upon the surface. The touch sensation is associated with that of sight, so that either may readily recall the other; and a similar light and shade perceived elsewhere may suggest the sensation of roundness. In the same ...