The Sense of Touch.
The sensations of smelling, tasting, hearing, and seeing, are conveyed by distinct organs, severally devoted to these objects, and all confined to the head. But the sense of touch, or feeling, extends over almost every part of the body. Though we may call every sensation feeling, yet what is properly denominated the sensation of touch, consists of the feeling or sensation excited by bodies brought in contact with the skin, and especially the tips of the fingers.
It is by the sense of touch, that men and other animals are able to perceive certain external qualities of objects. It is by this sense that we acquire ideas of hardness, softness, roughness, smoothness, heat and cold, weight and pressure, form and distance.
The accuracy of this sense is much improved by habit. In some cases, when persons have become deaf or blind, the sense of touch has grown so acute as partially to supply the loss of the sense of seeing or hearing. Blind persons have sometimes been able to determine the qualities of objects, with wonderful accuracy, by touch, and even to distinguish the colors of cloths, by being able to discriminate between the substances used in giving these their hues.