Part 8 (1/2)

It is true that man can accustom himself to nearly all kinds of odor, even to those that at first are very disagreeable He indeed not unfrequently so vitiates the sense of smell as actually to prefer those scents which, to persons who have preserved the integrity of this sense, are regarded as exceedingly offensive, and even filthy But why, let ive us the sense of smell? Was it to be thus perverted? No, indeed: it ithout doubt, that we rance of flowers and herbs, of food and drink; and also that we uish between air that is pure and healthful, and that which is ireeable to the senerally unwholesorateful to this sense are salubrious, and those odors which are pleasant are healthful, while air which is ungrateful will generally be found injurious to health, as will also all those odors which are unpleasant to this sense when in a healthful state He who has had occasion to enter a crowded court-room, lecture-room, church, or assembly-room of whatever kind, which has been occupied for a considerable time without adequate ventilation, can not fail to reans when first he inhaled the vitiated atht have become accustoh insensible to its noisome influence But let such and all others be well assured that, however offensive such a fetid atmosphere may be to the smell, it is equally injurious to the health And let those who, having returned fro walk or healthful exercise in a salubrious atmosphere, have had occasion to revisit the s-roo sleep, perceive, in the sickening smell, a sufficient cause for all their pains and aches, and wonder how they survived such a gross violation of the organic laws

All of the senses may be improved by education The sense of smell constitutes no exception to this rule Let none be discouraged, then; for the ans to pure air, the more will they require it, and the more readily will they detect the presence of the least impurity

This sense becomes very acute in deaf persons, and even more so in the case of those that are blind The reason is obvious; for, as they are led of necessity to rely upon it more than persons who have all the senses, it becoe of the properties of whatever is sub persons rarely partake of any article of food, and especially of any thing neithout first s it, and blind persons never; for this is the only e of its wholeso it

Whatever stupefies the brain, impairs the healthy action of the nerve of smell, or thickens the membrane that lines the nasal cavities, and thus diminishes the sensibility of the nerves ramified upon it, injures this sense All these effects are produced by the habitual use of snuff, which, when introduced into the nose, diminishes the sensibility of the nerves, and thickens the lining h the nostrils sometimes become completely obstructed It is on this account that most habitual snuff-takers are compelled to open their mouths in order to breathe freely It has been well said, that if Nature had intended that the nose should be used as a snuff-hole, she would doubtless have put it on the other end up

THE SENSE OF HEARING--The external ear, although curiously shaped, is not the an whose function it is to take cognizance of sounds In the transmission of sound to the brain, the vibrations of the air produced by the sonorous body are collected by the external ear, and conducted through the auditory canal to the drued that it htened like the head of an ordinary drum That its motion may be free, the air contained within the drum has free coe, called the Eustachian tube, leading to the back of the ree of deafness ensues But when the obstruction is re or otherwise, a crack or sudden noise is generally experienced, acco

The ear-drum performs a two-fold office; for while it aids in the transmission of sound from without to the internal ear, it at the sa of the sound is effected by the relaxation of a muscle when sounds are so acute as to be painful; but when listening to low sounds, the drum is rendered tense by the contraction of this muscle, and the sounds become, by this means, more audible The vibrations ular bony cavity--to the internal ear, which is filled with a watery fluid In this fluid the filaments of the auditory nerve terminate, which receive and transmit the sound to the brain

The ear has the power of judging of the direction froly exemplified in the fact that when horses or ht, those in front direct their ears forward, and those in the rear turn them backward, while those in the center turn the to be actuated by a feeling to watch the common safety This is also illustrated by four or six horse teams, and is a fact hich coach, and many other animals The external ear of es are said to have the power oftheir ears at pleasure, like a horse, to catch sounds as they come from different directions; but few men in civilized life retain this power

The acuteness of this sense inequal, depends upon the size of the ear In tie They are thus apprized of the approach of an enemy in time to flee to a place of safety

The ear-trumpet--which is a tube wide at one end, where the sound enters, and narrow at the other, where the ear is applied--is constructed on this principle, its sides being so curved that, according to the law of reflection, all the sound which enters it is brought to a focus in the narrow end It thus increases many fold the intensity of a sound which reaches the ear through it, and enables a person who has becoain with pleasure in society The concave hand held behind the ear answers in soree the purpose of an ear-trueons of Syracuse, was a notorious instance of a sound-collecting surface The roof of the prison was so formed as to collect the words, and even whispers, of the unhappy prisoners, and to direct the

Acuteness of hearing requires the healthy action of the brain, and particularly of that portion of it from which the auditory nerve proceeds, combined with perfection in the structure and functions of the different parts of the ear The best , is to observe well the general laws of health, and particularly to avoid every thing that will in the least impair the structure or healthy action of the parts immediately concerned in the exercise of this function Inflammatory fevers, affections of the brain, and injuries upon the head, are a Hence the i them, whether in the family or in the school The instances are not fehich deafness, and the i of the mental faculties, have resulted fro the ears” This inhuman practice is likely to result in injury to the dru thisits vibratory character Inflammation of the ear-drum, either acute or chronic, is the common cause of its increased thickness

How often this is produced by blows, the reader e Diminution of the vibratory character of the ear-drum may result from an accumulation of wax upon its outer surface In such cases chronic inflammation of the parts is not unfrequently the result of the injudicious practice of atte the heads of pins into the ear

This wax, it should be known, is designed to subserve an i fro, like the nose, constantly open, is liable to the entrance of foreign bodies, such as dust, insects, and the like But, fortunately, it is not left without the means of defense; for on its inside there are nu each other, interpose a barrier to the entrance of every thing but sound Moreover, between the roots of these hairs there are nulands, that secrete a nauseous, bitter hich, by its offensiveness, either deters insects froles them and prevents their advance in case they do enter This wax, then, is very serviceable But its usefulness does not stop here

When the ear beco becomes imperfect, as also when it is thin and purulent This wax not unfrequently beco less or more deafness But this forh it has existed for years; for, having softened the accu animal oil into the ear, they may be removed by the injection of warm soap-suds, which is an effectual and safe re is perhaps as susceptible of cultivation as any of the senses The Indian in the forest, who is accustomed to listen to the approach of his ene as to be able to detect sounds that would be inaudible to persons living amid the din of civilized life The blind, also, who of necessity are led to relypersons, excel in the acuteness of their hearing They recognize their acquaintances by the exercise of this sense as readily as persons usually do by that of sight, an attain persons make, and yet one that is perhaps within the reach of ninety-nine persons in every hundred The blind judge with great accuracy the distance of persons in conversation, of carriages in motion, and of all sonorous bodies whose vibrations reach their ears They even estiht of buildings by the reflection or interception of sound It is in consequence of the acuteness of this sense, acquired by careful cultivation, that the blind, as a class, have becouished for their pre-eminence in instrumental music This enables them also to cultivate vocal music with more than ordinary success

The due cultivation of the sense of hearing will contribute vastly to pro If it be true, as we are told it is by those who have been engaged in teaching both the deaf and the blind, that the absence of hearing is even a e than that of sight, weitself, or in the ly lessen the accuracy of the knowledge we receive through that organ The e very often is conveyed not so much by the words themselves as in the tones of voice in which the words are uttered If, therefore, the hearing be indistinct, or there be no habit formed of careful attention to the inflections of sound, the impressions received from e hear reeable, and be inefficient, even if it be not positively inarticulate We owe it to others, no less than to ourselves, then, to cultivate the powers of the voice--the coe of thought, sentih so common, is the most perfect of all instruments for the translected! how shamefully is it misused! It can be fully developed and h the influence of the ear If this organ be neglected, the voice must needs be ih life ireeable, because they were not carefully trained in early life to articulate distinctly, much less to utter _musical_ sounds The opinion is confidently expressed by those who are best qualified to decide the , if proper attention were paid early enough to the use they ans of sound The careful training of these should be considered an indispensable part of a school-teacher's as well as of a parent's duty

The ear will find appropriate discipline in distinguishi+ng, without aid fro of a door, the shutting of a knife, the dropping of various coins, theof different articles of furniture, etc Itthe direction fro acquaintances by their natural voices, and in detecting the counterfeit voices of co the ele all the different enus and species of birds by their chirping, of the distance and nature of sonorous bodies of various kinds, etc, etc These are so this sense: others will suggest thehtful reader

THE SENSE OF SIGHT--The sense of sight, which is the most refined and admirable of all the senses, still reenerally serve as interpreters between the material universe without and the spirit within But it is ht that we are enabled to hold converse with the external world Without it we should be deprived of a large portion of the pleasures of life not only, but even of the h the sense of vision that the wisdom, power, and benevolence of the Deity are chiefly manifested to us

I shall describe the apparatus of vision only so far as is necessary in order to subserveobject, which is the preservation and i it tributary to intellectual and an of vision, is an optical instrument of the most perfect construction It is surrounded by _coats_, which contain refracting mediums, called _humors_ There are three coats, called the _sclerotic_, the _choroid_, and the _retina_; and three humors, called the _aqueous_, the _crystalline_, and the _vitreous_

The _sclerotic_ or outer coat, called also the white of the eye, is an opaque, fibrous membrane It has almost the firmness of leather, possesses little sensibility, and is rarely exposed to inflammation or other diseases It invests the eye on every side except the front, and besidesits internal and delicate structure, serves for the attach in the fore part of this opaque coat is filled by the transparent _cornea_, which reseroove in the front part of the sclerotic coat in the salass is received into its case

But for this arrangeain admission to the eye

The _choroid coat_, which constitutes the second investing membrane of the eye, is of a dark brown color upon its outer surface, and of a deep black within The internal surface of thisblack paint, upon which the retina is spread out, and which is of great importance in the function of vision, as it seeht immediately after they have struck upon the sensible surface of the retina

The _retina_, which is the third and innermost membrane of the eye, is the expansion of the optic nerve, and constitutes the iement of the humors of the eye, and so perfectly are they adapted to the functions they are called upon to perfor the pupil is so refracted as to paint upon the retina an exact ie of the objects from which it proceeds The optic nerve, whose expansion fore and transmits it to the mind

Arnott has well remarked, that ”a whole printed sheet of a newspaper may be represented on the retina on less surface than that of a finger nail; and yet not only shall every word and letter be separately perceivable, but even any ile letter Or, ht an eye is turned up to the blue vault of heaven, there is portrayed on the little concave of the retina the boundless concave of the sky, with every object in its just proportions There a ed clouds, and surrounded by a thousand twinkling stars, so that to an animalcule supposed to be within and near the pupil, the retina lory”

Besides these three coats, and the cornea which constitutes about one fifth of the anterior portion of the outer coat, it is necessary to notice the _iris_, so called from its variety of color in different persons, and upon which alone the color of the eye depends The iris is a circular membrane situated just behind the cornea, and is attached to one of the coats at its circumference In its center is a small round hole, called the _pupil_; and soht of the eye, as no light can enter the eye except through it The iris possesses the power of dilating and contracting, so as to ade in the size of the pupil is effected by two sets of e froin of the pupil, and constitute the _radiated muscle_ The outer ends of these fibers are attached to the sclerotic coat, which is unyielding; hence, when they contract, the pupil _enlarges_ to receive ht The other set is coo round in the iris from the border to the pupil, and constitute the _orbicular muscle_, the contraction of which _diht enters the eye, the excited and sensitive retina ier, and the nerves, which are plentifully distributed to the iris, stimulate the orbicular muscle to contract, and the radiated one to relax, by which the size of the pupil is lessened But when the light which enters the pupil is insufficient to transe of objects to the brain, the orbicular muscle relaxes, and the radiated one contracts, so as to enlarge the pupil The contraction of the pupil is readily seen when a person passes froht is first brought into a roo Any personhi frohted room So, also, when a person looks at an object near the eye, the pupil contracts, but when he looks at an object more remote, it dilates The muscles of the iris are somewhat under the control of the will; for ree, at pleasure Soreat extent