212 PHYSIOLOGY AND HEALTH. 



is interesting to notice with what rapidity these sightless 

 children can read. They must of course perceive one letter 

 at a time, and, at the end of each word, determine what the 

 several letters spell. Yet, with this additional mental pro- 

 cess, they read nearly as fast as we do with the use of oui 

 eyes. This seems very easy when we see them do it ; but if 

 we shut our eyes, and then apply the fingers, not to a whole 

 word, but to a single letter, the letter #, for instance, we 

 shall find it is not so easy for the untrained to decipher the 

 raised marks. If we further attempt to read a word or sen- 

 tence, we shall be lost in the mazes of indistinguishable 

 characters. 



506. The blind are compelled thus to cultivate the sense 

 of touch, to compensate for their deficiency of sight. But 

 the power so to do is not confined to them. We all can do 

 the same, if we apply the same diligence ; and this we could 

 do if we had as strong a motive as they have. The cloth- 

 dresser learns to distinguish, by aid of the sense of touch in 

 his fingers, the qualities oi material, or minute differences 

 of texture, which others -cannot detect. The miller, in the 

 same way, detects the various qualities of meal and flour, 

 which escape the notice of others. In a great many of the 

 arts of life, the sense of touch is thus educated to be used 

 for minute and useful purposes. 



507. This sensibility is blunted by several causes. Cold 

 remarkably diminishes it. Our skin is numb when exposed 

 to a very low temperature, so that men sometimes cut or 

 bruise themselves, in winter, without feeling it; and the first 

 intimation which they have of their injury is the sight of 

 their flowing -blood. This sensibility is also impaired by the 

 natural excretions of the skin, by the mixture of the dead 

 scarf-skin, oil, and perspiration, with the dust and dirt, if not 

 removed from the surface. The blind man will wash his 

 fingers before he attempts to read his raised letters; and 

 the cook will pass through the same process when she leaves 

 her ordinary work, and takes up her fine sewing. 



