texture of this organ would excite some fear that it might readily suffer injury; but the eye may be compared to a room with a blind (iris), pane of glass (the cornea), and strong shutters (the lids), which do not resist violence, but endure it, without suffering injury, being so active, flexible, and resilient, that its very vibrations form its armour, as the yielding wave bears the haughty bark. The muscles, glands, nerves, and bones are more fully described in the diagram, which is drawn from a section adopted by that intelligent authority, Dr. Franz. The muscles move the eye towards the object; it centralizes upon every object, every letter of a book separately, but with such activity, that in a moment the eye has reported to the brain every object and colour in a room. The lachrymal glands supply all that lubricating moisture which prevents superficial injury to the organ in its active motion-the tears appear through the small orifices, and pass into the duct away. The optic nerves and arteries, the various humours, transparencies, and powers should be subjects of the greatest interest to those who delight in the study of the organs and physical abilities of the human frame: yet the author fears a more elaborate consideration of this part of these subjects would be scarcely acceptable in a little book, the chief object of which is (in a popular manner) to attract attention and deeper solicitude to the subject, and thus incite the reader to a more extensive examination of the nature (physically and philosophically) of this most solemnly interesting and highly important organ.

CHAPTER V.

COMPARISON WITH THE OTHER SENSES.

OUR subject rather invites a few words on the comparative character of the senses. Enjoyment appears universally to be the main end and rule, the ordinary and natural condition; while pain is but the casualty, the exception, the necessary remedy, which is ever tending to a remoter good, in due consideration to an ever higher law of nature. Here, as in every part of the physical economy, nature has endowed these organs with a direct and particular sensibility to those impressions which have a tendency to injure its structure; whereas they delight in those impressions which are not injurious. These external agents, which are capable of affecting the different parts of the nervous system, so as to produce sensation, are governed by laws peculiar to themselves. Their struc

ture is adapted in each particular to receive the impressions made by their respective agents, and are modified in exact conformity with the physical laws they obey. The structure of that part of the nervous system which receives visual impressions, viz., the retina, is adapted to the action of light; and the eye, through which the rays pass, is constructed with strict reference to that object.

The ear is formed to receive delicate impressions from those vibrations of the air which realize sound, and acquires a susceptibility of influences by its own appropriate agents, and by no others. In almost every case the impression

made upon the sentient extremity of the nerve which is appropriated to sensation, is not the direct effect of the external body, but results from the agency of some intervening medium. There is always a portion of the organ of sense interposed between the object and the nerve on which the impression is to be made. The object is never allowed to come in direct contact with the nerves; not even in the sense of touch, for there the organ is defended by the cuticle, through which the impression is made. This observation refers equally to taste and smell, the nerves of which are not only defended by the cuticle, but by secretion of mucous character, which averts any violent excitement. The two senses, which are more relative than others, are the sight and hearing, both which receive their impressions through the medium of the air.

We feel some hesitation on proceeding further on this interesting part of the subject,―viz., the comparison of the organs of sense and their respective physiological distinctions. If we were to go much deeper, we should soon find ourselves amidst those most interesting distinctions of sense, as delineated by the general animal kingdom-the touch of the ant, the sight of the fish, the hearing of the bird, the smell of the dog, &c. We would refer our readers to Buffon, Laurence, Hutin, Roget, and Walker, and conclude this part of our subject with but few observations.

Touch furnishes the relation of mechanical bodies; taste is adapted to chemical relations; smell also to chemical relations, but for the perception of substances in the aëriform state; hearing is for sound and its many modifications, tones which are produced by the internal vibration and motion of the particles of bodies and through the medium of air, &c. Our subject, the sense of sight, is adapted to light and its modifications, colour and shade,

and render to the perception the surface, form, and position of objects through the medium of light.

Sight and hearing seem to bear the most important characteristics, being employed on those objects which form the basis of human knowledge, viz., time and space.

An eloquent and scientific writer, reminds us that the great Mosaic record states, that a deep silence and repose, with a mysterious darkness, prevailed over the chaos of things, and God commenced his work by saying, "Let there be light." The sublime volume of revelation declares that on the last day a trumpet shall sound, announcing the judgment; then, amidst the tumult of the elements, shall the sun, moon, stars, and all temporal things, perish; but the spirit of man shall enter into the bright and resplendent mansions of eternity.

In man all these senses are susceptible of equal and simultaneous action, which is one of his leading distinctions from other animals. The habits and instinct of the brute demand that prompt and excelling vitality should attend particular organs. Even amongst the children of man, it may be observed, some seem more agile in the use of particular senses. The aborigines of some parts of the world will hear more readily and see objects at greater distance than the inhabitants of civilized cities; and this advantage may be traced to the fact, that they are very much in a state of nature, and, therefore, compelled to sustain their existence by daily use of their senses of sight and hearing, and have, at times, no other protection against sudden danger than the acute vigilance of these nerves. The inhabitant of the ice-bound wilds will be seen suddenly to lay upon his face and put his ear on the ice, by which he will learn what is approaching, though unseen. The wild bush man can see through marshy vapours, which would entirely eclipse the object from the eye of the

European. The savage can detect the footsteps of wild animals or his enemy, o'er mountain pass, o'er gloomy moor, and midst deep jungles, which would entirely elude the eye of civilized man. Here also is an evidence of the provident hand of the Creator, whose ample benevolence includes creation round, and not a child of man has been forgotten in his love.

Perhaps a summary of the ability of sight and hearing may be thus stated :—

Sight is adapted to light, colours, form, shape, numbers, &c.; written language, the works of art and nature.

Hearing is adapted to music, tones of all sorts, matter, quality, rest and motion in time; speech, the feelings, the sympathies, the finite and temporal.

There are some useful observations in Lord Malmesbury's Philosophy, and in Oken, of the German school; also in a more familiar, but very valuable work on natural philosophy, by the late Golding Bird.

We fear we are becoming tedious, and too abstracted; but, truth demands a basis; and we rejoice to say, that whenever we investigate the attributes of nature, we look upon eternal beauty and excellence. If we are able to test them by one or all the sciences, we award them the highest approval, and feel the sweetest interest in the investigation. Perhaps no subject is so full of excitement and interest as the economy of our own nature: its anatomy and physiology, its fashion and mechanical appliances are so truly in harmony with the strictest principles of science, whilst its sensibilities have a constant relation to the qualities of things external; indeed, we discern such a proportion of harmony and exact fitness, that the pains of the body, equally with its pleasures, seem appointed to balance and protect its delicate and wonderful structure. We must also observe