ed sight. are the

strike the optic nerve, and produce the sensation which is callThose branches which are spread over the tongue organ of taste. Those that are extended through the cavities of the nostrils are called the olfactory nerves. When the small particles of matter that escape from odoriferous bodies, come in contact with these nerves, they produce the sensation of smell.

The nerves that constitute the organ of hearing are extended over the cavity of the ear behind the tympanum, or eardrum. This cavity is filled with a liquid, and when the drum of the ear is caused to vibrate, by the air which is set in motion by sonorous bodies, it produces undulations of this liquid upon these nerves, and thus the sensation of sound is produced. The sense of feeling, by the expansion of other nerves, is extended all over the body, excepting the nails and the hair. It is by the action of matter in its different forms on these several senses, that the mind obtains ideas, and that ideas are imparted from one mind to another.

Perception never takes place, unless some material object makes an impression upon one of the senses. In the case of the eye, the ear, and the nostrils, the object which is regarded as the cause of the sensation, does not come immediately in contact with the organs of sense. When we see a body, we consider it as the cause of that perception, but it is not the body that comes in contact with the organ of sight, but merely the particles of light reflected from that body. In the case of smell, the fragrant body is regarded as the cause of the sensation, but the body that acts on the sense is the material particles of perfume that flow from that body.

Thus also with hearing. We consider the sonorous body as the cause; but the sensation is produced through the medium of the air, which affects the drum of the ear. But in the case of taste and touch, the body, which is regarded by the mind, as the cause, must come in contact with the nerves of the tongue or body, to produce the sensation.

Smell.

The sense of smell is one which greatly conduces to the preservation, the comfort, and happiness of man. It is a continual aid to him in detecting polluted atmosphere, or unhealthy food. The direct enjoyment it affords, is probably less in amount, than that derived from any of the other senses. Yet were we deprived of all the enjoyment gained through this source, we should probably find the privation much greater than we at first might imagine. When we walk forth among the beauties of nature, the fresh perfumes, that send forth their incense, are sources both of immediate and succeeding gratification. The beautiful images of nature, which rise to the mind in our imaginative hours, would lose many of their obscure but charming associations, were the fields stripped of the fragrance of their greens, and the flowers of their sweet perfumes. Nature would appear to have lost that moving spirit of life, which now ever rides upon the evening zephyrs and the summer breeze. As it is, while we walk abroad, all nature seems to send forth its welcome, while to its Maker's praise,

"Each odorous leaf,"

Each opening blossom, freely breathes abroad
Its gratitude, and thanks Him with its sweets.

Taste.

We

When a sapid body is applied to the organ of taste, two sensations are produced, one of touch, and one of taste. are conscious of the difference of these sensations, when we apply a tasteless body to the tongue, and then immediately apply one which has taste. In the last case we have the sensation of touch as before, and in addition to it, the sensation of taste. It is probable however that the same set of nerves serve both purposes.

It is one of the numberless evidences of the goodness of our Creator, that the process which is necessary for the preservation of life, and which depends upon the voluntary activity of every human being, should be connected with a sense, which affords such gratification, that the duty is sought as a pleasure. Were mankind led to seek food, merely in the exercise of reason, for the purpose of preserving life, multitudes through carelessness and forgetfulness, would be perpetually neglecting that regular and necessary supply of aliment, without which, the animal system would become deranged and enfeebled. By the present constitution of the body, the gratification of this sense, is an object of desire, and thus we are continually reminded of our duty, and led to it as a source of enjoyment.

Nor is it the gratification of this sense, which is the only source of enjoyment connected with it. The regular periods for repast, bring around the social board, those united to each other by the tenderest ties of kindred and affection. These become seasons of cheerful hilarity and relaxation, seasons of cessation from daily cares, seasons for the interchange of kind feelings and intellectual stores; and while the mere gratification of sense is one source of pleasure, to this is often added the "feast of reason and the flow of soul." The effects on the best feelings, in thus assembling to participate in common blessings, is scarcely ever appreciated. Did every individual of our race retire to secrecy and solitude to satisfy the cravings of nature, how much would the sum of human happiness be diminished! But thus has our benevolent Creator contrived, that one source of enjoyment should serve as an occasion for introducing many more.

Hearing.

The sense of hearing is one more connected with the intellectual and moral powers of man, than either taste or smell, as it is through the medium of this organ that both music and

speech operate on the human mind. We can form some imperfect estimate of the amount of happiness derived from this sense, by imagining the condition of mankind, were they at once and forever deprived of this source of improvement and enjoyment. The voice of sympathy, friendship, and love, would be hushed. The eloquence of the forum, the debates of the legislature, the instructions of the pulpit would cease. The music of nature, its sighing winds, and dashing waters would be stilled, and the warbling of the groves would charm no more. The sound of pipe, and harp, and solemn harmonies of voice, would never again waken the soul to thrilling and nameless emotions. Man would walk forth in silence and solitude, where now, ten thousand sounds of active life, or cheerful hum of business, or music of language and of song, charm and animate the soul.

The operation of mere sound, disconnected with the ideas which are often conveyed by it, is a subject of curious speculation. Sounds differ from each other in tone, in pitch, and in force or strength. The difference in tone may be illustrated by the sounds of a clarionett, compared with the sound of a bell, or of the human voice. Every instrument, and every human voice, has each a peculiar tone by which it is distinguished from all others. The difference in pitch is shown by sounding a low and high note in succession, on an instrument. The difference in force is exhibited by singing or speaking loud or soft.

There are certain sounds that in themselves are either agreeable or disagreeable from their tone alone. Thus the sound of a flute is agreeable, and that of the filing of a saw, is disagreeable. Sounds also are agreeable according as they succeed each other.

Melody is a succession of agreeable tones, arranged in some regular order as it respects their duration and succession. Some melodies are much more agreeable to the ear than others. Some melodies produce a plaintive state of mind; oth

ers exhilarate, and this without regard to any thing, except simply the nature of the sounds and their succession. Thus a very young infant, by a certain succession of musical tones, can be made either to weep in sorrow, or smile with joy.

Harmony is a certain combination of sounds which are agreeable to the ear, and it is found that the mind can be much more powerfully affected by a combination of harmonious sounds, than by any melody. The effect of music on certain minds is very powerful, often awakening strange and indescribable emotions. It has been therefore much employed both to heighten social, patriotic, and devotional feeling.

There is probably nothing which produces stronger and more abiding associations in the mind than musical sounds. As an example of this, may be mentioned the national air which is sung by the Swiss in their native valleys. It is said that when they become wanderers in foreign lands, so strongly will this wild music recall the scenes of their childhood and youth, their native skies, their towering mountains, and romantic glens, with all the strong local attachments that gather around such objects, that their heart sickens with longing desires to return. And so much was this the case with the Swiss of the French armies that Buonaparte forbade this air being played among his troops. The Marseilles Hymn, which was chanted in the scenes of the French Revolution, was said to have been perfectly electrifying, and to have produced more effect than all the eloquence of orators, or machinations of plotting statesmen.

The mind seems to acquire by experience only, the power of determining the place whence sounds originate. It is probable that at first, sounds seem to originate within the ear of the person who hears, and even after long experience, cases have been known, when a person suddenly waked from sleep, imagined the throbbing of his own heart was a knocking at the door. But observation and experience soon teach us, the direction and the distance of sounds. The art of the ventrilo