'MUCH, or FEELING, sense of. When the mind has connected the complex. ideas derived from the touch with the vi sible appearance of objects, then the sight is indefinitely the most useful medium of knowledge : but in the earliest stages of the intellectual progress, the touch is the most useful ; in fact, as man is formed, it then is absolutely necessary to render the sight productive of most of its present utility. The sense of feeling differs from the other senses in belonging -to every part of the body, external or internal, to which nerves are distributed. The term touch is most correctly applied to the sensibility which is diffused over the sur face of the body. Touch exists with the most exquisite degree of sensibility at the extremities of the fingers and thumbs, and in the lips. The sense of touch is thus very commodiously disposed for the purpose of encompassing smaller bodies, and for adapting itself to the inequalities of larger ones.
The sensations acquired by the sense of feeling are those of heat, hardness, so. lidity, roughness, dryness, motion, dis tance, figures, &c. .and all those corporeal feelings which arise from a healthy or dis eased state of the nerves, and the part of the body to which they belong.
The pains of this sense are more nume rous and vivid than those derived from any other sense ; and therefore the relicts of them, coalescing with one another, con stitute the greatest share of our mental pains, that is, pains not immediately de rived from sensation. On the other hand, its pleasures being faint and rare, in com parison with others, and particularly those of the taste, have but a small share in the formation of the mental pleasures.
The touch is the original medium of our knowledge respecting the real quali ties of substances, and is indeed the sole medium by which we gain a knowledge of external objects. It is by the touch, and by the touch alone, originally, that we distinguish our own bodies from other objects that surround us, and form the impression which every one has, that the objects which affect the sight, the hear ing, &c. are external. When we touch a sensible part of our bodies, we have sen sations conveyed to the mind through two different nervous branches ; when we touch any other body, we have only one sensation.
The impression that they are external objects, that is, objects out of ourselves, which give us the sensations of sound, taste, sight, and smell, is so continually forced upon us by the sensations of touch, that there probably never was found a person, who doubted the existence of the external world as the cause of his sensa tions, except those who have been led to it by reasoning on false principles. Some
very acute speculators have indeed given up the belief in an external world as the cause of their sensations ; but their opini on never did, nor never can, gain much ground ; for it is inconsistent with the perceptions, which, by the constitution of our frame, are necessarily formed from continually recurring sensations. The phi, losophic Berkeley, and a late writer, Drummond, are the principal supporters of this curious system. But if we had not the sense of touch, the other senses would have produced no such impression; sen sations would have appeared to arise in the mind without any connection with external causes of them.
Some philosophers have supposed, that it is the exluisite delicacy of feeling which exists in the hand, and the admi rable mechanism by which it is applied, which is the cause of the superiority of knowledge which man possesses over the lower classes of animals. It cannot be just to attribute to this cause alone this superiority; but indisputably, as man is constituted, it is essential to the degree of superiority now possessed ; and we observe, that that tribe of animals pos sesses the greatest degree of what may be called human wisdom, which has this sense most perfect ; the bended muscle at the end of the elephant's trunk an swering some of the purposes of the hu man fingers.
Touen needle, among assayers, refiners, &c. little bars of gold, silver, and copper, combined together in all the different proportions and degrees of mixture ; the use of which is to discover the de gree of purity of any piece of gold or silver, by comparing the mark it leaves on the touch-stone with those of the bars.
The metals usually tried by the touch stone are, gold, silver, and.copper, either pure, or mixed with one another in dif ferent degrees and proportions, by fusion. In order to find out the purity or quanti ty of baser metal in these various admix tures, when they are to be examined, they are compared with these needles, which are mixed in a known proportion, and prepared for this use. The metals of these needles, both pure and mixed, are all made into lamina: or plates, one twelfth of an inch broad, and of a fourth part of their breadth in thickness, and an inch and a half long ; these being thus prepared, you are to engrave on each a mark, indicating its purity, or the nature and quantity of the admixture in it.