Part 4 (1/2)

LETTER VI

THE TEETH _(continued)_

I left off at the _molars_, which are the teeth one selects to crack nuts with; and if I re with scissors

Let us look at the subject from a distance, that wea heavy cart slowly along

Ask it to gallop, and it will answer, ”With all e to draw” And now fancy another flying over the ground with a gig behind it Ask it to exchange the gig for the cart, and it will say, ”Yes; but then I shall have to go slowly”

Whereby you see that with the sath to ith, one has the choice of two things: either of conquering a great resistance slowly, or a slight one quickly

And it is partly on this account, dear child, that I teach you so gradually; for young heads, fresh to the work, are less easily drawn along than others, and have but a certain ath

Hitherto all has been clear as the day Now take your scissors in your left hand; hold the lower ring of the handle firmly between your thuht and io up and down, and watch the blade as it moves The whole of it moves at once, and is put in ht hand But the point e end makes only a very little one--indeed, ine, a different sort of effort is required fro as resistance is allop: it is the horse in the gig; the light work is for hie moves slowly; it is the cart-horse, and takes the heavy labor

I hope I haveof our nut, though you may not suspect it Move your scissors once more in the same way Now, you have before you the pattern of the ts on one side of your face, from the ear to the nose; the upper one, which never er on your upper lip when you either speak or eat), and the lower one which goes up and doo pairs of scissors set points to points give you the whole jaw The _incisors_ are at the points, they gallop up and down, and are worthless for doing hard work; the _ tough has to be dealt with, it comes to them as a matter of course; hence they are the nutcrackers You must own that it is pleasant to reflect thus upon e are doing every day, and the next ti stones of twenty tiht with his iron bar, ask your papa to explain to you the principle of the lever After what I have told you, you will understand it very readily, or at least enough of it to satisfy yourup and down, the lower jaw possesses another less obvious one, by ht to left

This is precisely what naughty children rind their teeth: not that I mean this remark for you, for I have a better opinion of you than to suppose you do such things Those who make such bad use of their jaws deserve to lose the power of everthem thus, and then they would find themselves sadly at a loss how to chew their bread--for their _molars_ would be of but little service to them in such a case; as it is chiefly by this second action of the jaw that the food is pounded Try to chew a bit of bread by onlyyour jaw up and down, and you will soon tire of the attempt

One word more to complete my description of the teeth: that portion of them which is in the jaw is called the _root_; and the _incisors_, which cannot work hard because, like the gig-horses, they have but little resisting power, possess only small and short roots; whereas the _canines,_ whose duty it is to tear the food sideways, would run the risk of being dragged out and left sticking in the substances they are at work upon, if they were not well secured; these, therefore, have roots which go ive us more pain than the others when the dentist extracts them: those famous _eye-teeth_, which so terrify people on such occasions, are the _canines_ of the upper jaw, and lie, in fact, just below the eye

The _ shaken in the sideway : so they do as you would do if you were pushed aside Now you would throw out your feet right and left in order to steady yourself, and thus the ht and left for the same purpose Some have three, some four, and they require no less for the business they have to do

Above the root comes what is called the crown; that is the part of the tooth which is exposed to the air; the part which does the work, and which bears the brunt of all the rubbing Noever hard itworn out by all this fun if it were not covered by a still harder substance, which is called _ena of china plates, and which you can easily distinguish by exaive you a very exact idea of it It is this enaives the teeth the polish and brilliancy we so much admire, and it is desirable to be very careful of it, not out of vanity, though there is no objection to a little vanity on the subject, but because the enamel is the protector of the teeth, and when that is destroyed, you ood-bye to the teeth thear or lemon-juice does intothis protecting armor of the teeth is never to eat the unripe windfalls of fruit, which I have seen unreasonable children pick up in orchards and devour so recklessly They give sufficient warning, by their acidity, that they are not fit for food, and when this warning is neglected, they take their revenge by corroding the enamel of the teeth; not to speak of the disturbance which they afterwards cause in the poor sto of enamel, the teeth would be prematurely worn out, the reason of which is, that the teeth have not the property of growing again, as the nails and hair have When those little geran to describe the teeth, have finished their work, they perish and fall out, like masons hen they have built the house, take their departure forever

But the ”forever” wants explanation For such stern conditions would fall hard on very little children, who, not having coreat value of their teeth, and take all the care they need of theiven

Your first teeth, the _: they are a kind of speci

When you are approaching what is called the age of reason, (and this word ireat deal, my dear child,) the real teeth, the teeth which are to serve you for life, begin to whisper a reasonable, and ill soon, or else never, be fit to take charge of her teeth” No sooner said than done: other masons set to work in other cells, placed under the first set, and as the perradually push out thetheir places ready for them till they came

This is just your case at present, and you now understand your responsibility, and how necessary it is to preserve those good teeth which have placed so generous a confidence in your care of theone, can never be replaced

You have no loss by the exchange; you had twenty-four at first, you will now have twenty-eight Twenty-eight, did I say? nay, you will have thirty-two; but the last four will come later still The last _molars_ on each side, above and below, in both jaill not rown up They are a fastidious and timid set, and will not run any risks; and they are called _wisdom-teeth_, because they do not appear till we are supposed to have arrived at years of discretion Some people do not cut theree that, if they have not become wise by that ti so!

There is much more still to be said about the teeth; but I think I have told you quite enough to teach you the importance of these little bony possessions of yours, which children do not always value as they deserve, and whose safety they endanger as carelessly as if they had fresh supplies of them ready in their pockets If sous to masticate our food properly, it is clear that this process is not an unimportant one

Those, therefore,a et that they are thereby forcing the stolected to do, and this is very bad economy, I can assure you You will see hereafter, e speak about animals, that by a marvellous coreat in proportion to the _in_efficiency of the teeth, and that by the same rule, it is weakest when the jaws are best furnished Now, no jaw is more completely furnished than the human one; it is clear, then, that it should do its oork and not leave it to be done by those who are less able: and the little girl who, in order to finish her dinner more quickly, shi+rks the use of her teeth, and sends food, half chewed, into her sto and vigorous, the other feeble and delicate, allows the first to dawdle at his ease, and puts all the hard work on the other

He would be very unjust in so doing, would he not? And as injustice always meets with its reward, his work is sure to be badly done

Now, the work in question consists in reducing e eat into a sort of pulp or liquid paste, from which the blood extracts at last whatever it requires But the teeth may bite and tear theof the their labors they were not assisted by an indispensable auxiliary To make pap for infants what do we add to the bread after it is cut in little bits? Without being a very clever cook, you will know that it is water which is wanted And thus, to assist us inpap for the blood, Providence has furnished us with a nuans within the mouth, which are always filled ater These are called _salivary glands_ This water oozes out from them of itself, on the least oes up and down The name of this water, as I need scarcely tell you, is _saliva_

When I call it water, it is not merely from its resemblance; _saliva_ is really pure water with a little _albumen_ added Do not be afraid of that word--it is not so alar as it appears to be It _ There is also a little soda in the water, which you know is one of the ingredients of which soap is made And this explains why the saliva becoue set it in ; just as the whites of egg, or soapy water, become frothy hipped up or beaten in a basin

But the albumen and the soda have not been added to the saliva, in our case, merely to make it frothy; that would have been of very little use They give to the water a greater power to dissolve the food into paste, and thus to begin that series of transforradually becomes the fine red blood which shows itself in little drops at the tip of your finger when you have been using your needle aardly