into a prompt and decisive habit, we at once separate these confused elements, supply the breaks in their connection, fill up the deficiencies, and make out a continuous and significant whole. And yet this is done so rapidly, and is so common, that in most cases we imagine there is nothing more than the pure and unmixed sensation. §. 102. 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 inductions from them. Diderot relates of the blind man of Puiseaux mentioned in a former section, that he was capable of judging of his distance from the fire-place 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 * It is a singular circumstance, that something similar to what is here stated of the ability of blind men to discover the nearness or distance of objects by changes in the resistance of the atmosphere, has been noticed by the naturalist, Spallanzani, in respect to bats. He discovered that bats, when perfectly blinded and afterwards set at liberty, had the extraordinary faculty of guiding themselves through the most complicated windings of subterraneous passages, without striking against the walls, and they avoided with great skill, cords, branches of trees, and other obstacles, placed by design in their way. This ability is probably owing to an extreme delicacy in the wing, which is of a very large size in proportion to that of the animal, and is covered with an exceedingly fine net-work of nerves. The bat, as it strikes the air with its wing, receives sensations of heat, cold, and resistance, and, in consequence is enabled to avoid objects, which would otherwise obstruct its flight, apparently in the same way that blind persons perceive a door or a wall by a change in the temperature or in the resistance of the air. 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. * 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 waggoner 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 indiffereutly 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 vallies, 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 • Memoirs of the Manchester Philos. Society, Vol. I, p. 164. 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 leant to distinguish, one letter from another, and also to combine them into syllables and words, are able after a time to pass their fingers along the words and sentences of these printed sheets, and ascertain their meaning with a good degree of rapidity. Perhaps it may occasion some surprise, when we add, that men may not only read by the touch, but may even find a substitute for the hearing in that sense. Persons, who were entirely deaf, have in some instances discovered a perception of the proportion and harmony of sounds. "It will scarcely be credited, (says an English writer, speaking of one in that situation,) that a person thus circumstanced should be fond of music; but this was the fact in the case of Mr. Arrowsmith. He was at a gentleman's glee club, of which I was president at that time, and, as the glees were sung, he would place himself near some article of wooden furniture, or a partition, door, or window shutter, and would fix the extreme end of his finger nails, which he kept rather long, upon the edge of some projecting part of the wood, and there remain until the piece under performance was finished, all the while expressing, by the most significant gestures, the pleasure he experienced from the perception of musical sounds. He was not so much pleased with a solo, as with a pretty full clash of harmony; and if the music was not very good, or I should rather say, if it was not correctly executed, he would show no sensation of pleasure. But the most extraordinary circumstance in this case is, that he was most evidently delighted with those passages, in which the composer displayed his science in modulating the different keys. When such passages happened to be executed with precision, he could scarcely repress the emotions of pleasure which he received within any bounds; for the delight he evinced seemed to border on extacy."* London Quarterly Review, Vol. XXVI, p. 404. §. 103. 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 necessity of this frequent reference to it will be found to be peculiarly great, where a person is deprived of two of his other senses. It 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. This 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. 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. §. 104. 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 knew a man in the Greek island of Hydra, who was ac customed 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 sale belonging to the island, he would tell the name of each one, as she approached, with unerring certainty, while she was still at such a distance as to present to a common eye 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 skillful 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 of Geneva.-"At two years old (he says) it was perceived, that she had lost her hearing, |