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determined pretty nearly the stature of those he wa conversing with by the direction of their voices; and he made tolerable conjectures respecting their tempers and dispositions by the manner in which they conducted their conversation "
ý 51. Application of habit to the touch.
The sense of touch, like the others, may be exceedingly improved by habit. The more we are obliged to call it into use, the more attention we pay to its intimations. By the frequent repetition, therefore, under such circumstances, these sensations not only acquire increased intenseness in themselves, but particularly so in reference to our notice and remembrance of them. But it is desirable to confirm this, as it is all other principles from time to time laid down, by an appeal to facts, and by careful induc
tions from them.
Diderot relates of the blind man of Puiseaux, mention ed in a former section, that he was capable of judging of his distance from the fireplace by the degree of heat, and of his approach to any solid bodies by the action or pulse of the air upon his face. The same thing is recorded of many other persons in a similar situation; and it may be regarded as a point well established, that blind people who are unable to see the large and heavy bodies presenting themselves in their way as they walk about, generally estimate their approach to them by the increased resistance of the atmosphere. A blind person, owing to the increased accuracy of his remaining senses, especially of the touch, would be better trusted to go through the various apartments of a house in the darkness of midnight, than one possessed of the sense of seeing without any artificial light to guide him.
In the celebrated Dr. Saunderson, who lost his sight in very early youth, and remained blind through life, although he occupied the professorship of mathematics in the English University of Cambridge, the touch acquired such acuteness that he could distinguish, by merely letting them pass through his fingers, spurious coins, which were so well executed as to deceive even skilful judges who could see.*
* Memoirs of the Manchester Philosophical Society, vol. i., p. 164.
The case of a Mr. John Metcalf, otherwise called Blind Jack, which is particularly dwelt upon by the author of the Article in the Memoirs just referred to, is a striking one. The writer states that he became blind at an early period; but, notwithstanding, followed the profession of a wagoner, and occasionally of a guide in intricate roads during the night, or when the tracks were covered with snow. At length he became a projector and surveyor of highways in difficult and mountainous districts; an employment for which one would naturally suppose a blind man to be but indifferently qualified. But he was found to answer all the expectations of his employers, and most of the roads over the Peak in Derbyshire, in England, were altered by his directions. Says the person who gives this account of Blind Jack, "I have several times met this man, with the assistance of a long staff, traversing the roads, ascending precipices, exploring valleys, and investigating their several extents, forms, and situations, so as to answer his designs in the best manner."
In the interesting Schools for the Blind which have recently been established in various parts of the world, the pupils read by means of the fingers. They very soon learn by the touch to distinguish one letter from another, which are made separately for that purpose of wood, metals, or other hard materials. The printed sheets which they use are conformed to their method of studying them. The types are much larger than those ordinarily used in printing; the paper is very thick, and being put upon the types while wet, and powerfully pressed, the letters on it are consequently raised, and appear in relief. The pupils having before learned to distinguish one letter from another, and also to combine them into syiiables and words, are able after a time to pass their. fingers along the words and sentences of these printed theets, and ascertain their meaning, with a good degres of rapidity.
§ 52. Other striking instances of habits of touch.
The power of the touch will increase in proportion to the necessity of a reliance on it. The more frequent the resort to it, the stronger will be the habit; but the neces
sity of his frequent reference to it will be found to be peculiarly great where a person is deprived of two of his other senses is noticed of James Mitchell, whose case has been already referred to, that he distinguished such articles as belonged to himself from the property of others by this sense. Although the articles were of the same form and materials with those of others, it would seem that he was not at a loss in identifying what was his own. It will be recollected that he could neither see nor hear, and was, of course, speechless. He was obliged, therefore, to depend chiefly on the touch. This sense was the principal instrument he made use of in forming an acquaintance with the strangers who frequently visited him. And what is particularly remarkable, he actually explored by it, at an early period, a space round his father's residence of about two hundred yards in extent, to any part of which he was in the practice of walking fearlessly and without a guide, whenever he pleased.
It is related of the deaf and blind girl in the Hartford Asylum, that it is impossible to displace a single article in her drawers without her perceiving and knowing it; and that, when the baskets of linen are weekly brought from the laundress, she selects her own garments without hesitation, however widely they may be dispersed among the mass. This is probably owing, at least in great part, to habits of touch, by means of which the sense is rendered exceedingly acute.-Diderot has even gone so far as to conjecture that persons deprived of both sight and hearing would so increase the sensibility of touch as to locate the seat of the soul in the tips of the fingers
53. Habits considered in relation to the sight.
The law of habit affects the sight also. By a course of training this sense seems to acquire new power. The length and acuteness of vision in the mariner who has long traversed the ocean has been frequently referred to. --A writer in the North American Review (July, 1833) says, he once 66 knew a man, in the Greek island of Hydra, who was accustomed to take his post every day for thirty years on the summit of the island, and look out for the approach of vessels; and although there were over
three hundred sail belonging to the island, he would tell the name of each one as she approached with unering certainty, while she was still at such a distance as to present to a common eve only a confused white blur upon the clear horizon." There are numerous instances to the same effect, occasioned by the situations in which men are placed, and the calls for the frequent exercise of the sight. The almost intuitive vision of the skilful engineer is, beyond doubt, in most cases merely a habit. He has so often fixed his eye upon those features in a country which have a relation to his peculiar calling, that he instantly detects the bearing of a military position, its susceptibility of defence, its facilities of approach and retreat, &c.
No man is born without the sense of touch, but many are born without the sense of hearing; and, wherever this is the case, we are entitled to look for habits of sight Persons under such circumstances naturally and necessarily rely much on the visual sense, whatever aids may be had by them from the touch. Hence habits; and these imply increased quickness and power, wherever they exist. It is a matter of common remark, that the keenness of visual observation in the DEAF and DUMB is strikingly increased by their peculiar circumstances. Shut out from the intercourse of speech, they read the minds of men in their movements, gestures, and countenances. They notice with astonishing quickness, and apparently without any effort, a thousand things which escape the regards of others. This fact is undoubtedly the foundation of the chief encouragement which men have to attempt the instruction of that numerous and unfortunate class of their fellow-beings. They can form an opinion of what another says to them by the motion of the lips; and sometimes even with a great degree of accuracy. That this last, however, is common, it is not necessary to assert; that it is possible, we have the testimony of well-authenticated facts. In one of his letters, Bishop Burnet mentions to this effect the case of a young lady at Geneva.-" At two years old," he says, "it was perceived that she had lost her hearing, and ever since, though she hears great noises, yet hears nothing of what is said to her; but, by
observing the motion of the lips and mouths of others, she acquired so many words, that out of these she has formed a sort of jargon in which she can hold conversation whole days with those who can speak her language. She knows nothing of what is said to her, unless she sees the motion of their lips that speak to her; one thing will appear the strangest part of the whole narrative. She has a sister with whom she has practised her language more than with anybody else, and in the night, by laying her hand on her sister's mouth, she can perceive by that what she says, and so can discourse with her in the dark.” (London Quarterly Review, vol. xxiv, p. 399.)
Such are the views which have been opened to us in considering the law of HABIT in connexion with the senses; and we may venture to say with confidence, that they are exceedingly worthy of notice. There are two suggestions which they are especially fitted to call up. They evince the striking powers of the human mind, its irrepressible energies, which no obstacles can bear down. They evince also the benevolence of our Creator, who opens in the hour of misery new sources of comfort, and compensates for what we have not, by increasing the power and value of what we have.
54. Sensations may possess a relative, as well as positive increase of power.
There remains a remark of some importance to be made in connexion with the general principle which has been brought forward, and as in some measure auxiliary to it; for it will help to explain the more striking instances of habits, if any should imagine that the fact of mere repetition is not sufficient to account for them. Our sensations and perceptions may acquire not only a direct and positive, but a relative and virtual increase of power.
This remark is thus explained. We shall hereafter see the truth of an important principle to this effect, that there will be a weakness of remembrance in any particular case in proportion to the want of interest in it. Now hundreds and thousands of our sensations and perceptions are not remembered, because we take no interest in them. Of course they are the same, relatively to our amount of