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his face, and told Simon that on the last day, when the books should be opened, he would meet with the just judgment of God for all his cruelties. Three women only recanted; they were forcibly held back by the noble lady of Marly, the mother of Bouchard, Lord of Montmorenci; terror and consternation succeeded to the enthusiastic fervour which had hitherto supported them, and consenting to be converted, they were saved from the flames.

AMUSEMENTS IN SCIENCE. No. VIII.

GEOMETRY.-Part 5.

To draw a right angle without any other instrument than a straight stick and two or three pegs. Draw the straight line F A c B, and h make FA, A c, and c B, equal \ to each other; from c draw CI: the straight line c D d in any direction, make c D equal to c A, and draw the line D h through the point A, draw the line F G, through any part of D h, and make E G equal to E F. The point G will then be exactly perpendicular to A, and the line GA, when drawn, will be at right angles with A B, and consequently the angle A is a right angle. To measure the superficial contents of a rectangular piece of ground. Suppose A B to be equal to twenty feet, and c B to nine feet; multiply | twenty by nine, which produces one hundred and eighty; this would be the contents of the square plot of ground A B C D, and consequently, the contents of the triangular plot would be equal to one-half one hundred and eighty, namely, ninety feet.

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Fig. 1.

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A BRICKLAYER had to construct a wall whose length in the direction A B C was twenty-four feet. The onehalf of this wall, namely, from B to c, had to be built

Fig. 3. A B C

over a piece of rising ground, so that the base of this part of the wall would necessarily be more than twelve feet. In making out his account he charged more for this half of the wall than for that which was built on level ground from A to B. A geometrician assured him that the square contents of both portions of the wall were exactly alike, which may be proved in this manner. Cut two pieces of card

Fig. 4. Fig. 5. board in the form shown in figs.'4 and 5, to represent the two parts of the wall; lay the piece representing the straight wall on the curved piece, and it will be found that the angles which project at A and B will exactly fill up the spaces at E and F. The piece of pasteboard representing the straight wall, may thus be proved to be exactly sufficient to form a piece equal to that representing the curved wall. You may then lay the curved piece upon the straight one, and reversing the experiment, prove that the curved piece

is capable of forming a rectangular piece equal to the other.

ON EMPLOYMENTS WHICH INJURE THE
EYE-SIGHT.
No. I.

A POPULAR DESCRIPTION OF THE ORGANS OF SIGHT.

MAN in his present temporary position on the globe, is subject to all the physical laws which, under the direction of a superintending Providence, govern the universe. He is endowed with certain perceptions, by whose means alone, he communicates with the exterior world and acquires all his knowledge. These perceptive faculties are admirably fitted for use in the strict sense of the word, and it seems to be a law of nature, as rigid as it is grand and beautiful, that the natural laws are self-acting; that is, they bear with and inflict of themselves their own penalties. If, for example, we exceed the use of any one faculty; so soon as the use intended by nature is exceeded, the abuse of the faculty begins, and then also the penalty attached to the law of nature, which regulates the use, begins. Pain is the most apparent symptom of abuse, and usually accompanies it ; but the most awful, and awful because mysterious, operation of the penalty is, the slow and premature loss of the use of the faculty either in part or wholly: the faculty then ceases to act; and its possessor, because he has abused one of nature's gifts, is deprived of it. And here there is no court of appeal: it is useless to urge ignorance of the powers of the faculty, since nature began by inflicting her penalty by slow degrees, either by imparting to the possessor small increments of pain, or partial deprivation of the power of the faculty, so as to urge, as it were, upon the owner, gently, and in her own beautiful way, the necessity of complying with those laws which never vary, by chiding him for being so hard a taskmaster as to exact from a faithful servant a task which it was never calculated to supply. Many of the arts of life furnish employments which injuriously affect the faculties of those employed in them : what these pursuits are, and how they operate, is a curious and instructive inquiry, into which, as far as respects the organ of sight, we are now about to enter, with the hope that our readers generally will find it useful, and some of them in particular will, we doubt not, find the subject one of more than common interest as it affects themselves peculiarly. We shall point out how, in many employments, the faculty of vision is injuriously affected or abused, and the simple and practicable means of removing the abuse. We select the organ * of sight as being probably the most extensively useful of all our faculties, and the one most liable to abuse. We propose, in order to the due comprehension of our present subject, to describe the organ and function of the eye somewhat fully; and as many of the visual imperfections to be hereafter described are the results of the writer's own personal experience, the present paper may be considered partly as an exposition of the writer's own visual defects, and also how such defects may be traced to a large variety of causes more or less energetic in their action, but whose proximate operation is nearly the same. 1. The eye, which, from the wonderful power of its exterior expression, and the exquisite beauty of its internal arrangements, is said to be “Nature's masterpiece,” is a globular structure placed within an orbit, or funnel-shaped cavity, on one side of the root of the nose and under the arch of the forehead. The

• We may here state, that an organ is the physiological drrangement of parts through which the function, or work done by the organ, acts. Thus the eye is the organ of sight; seeing, therefore, is the function. The ear is the organ of hearing, and hearing the function, &c.

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eye-ball is a little smaller than this socket or orbit, to allow of free motion in every direction: this motion is effected by means of a muscular arrangement attached to the white of the eye, and the motion is rendered easy, and at the same time the eye is defended from injury or compression in its motion, by a quantity of fat which in health is secreted in the orbit, forming several soft cushions on which the globe of the eye rests. When this fat is absorbed by any emaciating disease, the eye sinks within its socket, and a person is then familiarly termed “holloweyed.” The eye itself is composed chiefly of three humours (one of which is solid and the others fluid), and four membranous coats or tunics: the humours completely fill the eye, and give it its shape, and at the same time support the membranous coats. The white of the eye, or the slerotica, so named from its hardness, is the exterior coat, and forms the whole of the outer eye-ball, with the exception of about one-fifth, which latter space is occupied by the cornea, (so called from its horny texture,) a transparent shield placed in front of the eye, through which the rays of light pass uninterruptedly. The cornea receives its lustre and polish from the eyelids, which are constantly engaged in folding over it; and our readers will doubtless call to mind that one of the first acts of the cold though active hand of Death, is to dull the transparency of this beautiful convex mirror, which reflects all objects presented to it; while life, health, and youth, preserve its properties unimpaired. The tendency of age is to flatten the cornea, and to diminish its transparency and polish; hence, it is said, that the eye of age is dim; and by a converse application the eye of youth is said to be lustrous, sparkling, beaming, &c., since in this case the cornea is a convex mirror, whose polish reflects light from its surface, while its transparency transmits light into the eye for the purposes of vision. The white of the eye is lined internally with a membrane of a more delicate structure, called the choroid coat, or tunic, which is covered with a black non-transparent pigment, placed there for the purpose of absorbing the rays of light when the purpose of vision has been served. Within the choroid coat is the retina, (so called from its reticulated or net-like structure,) which is a very delicate membrane, formed from the expansion of the optic nerve, which enters the eye at a point nearly opposite the pupil. In the centre of the retina there is a small spot surrounded with a yellow margin; this spot is miscalled the foramen centrale, or central hole; for it is not a hole but a spot; and it is remarkable, that while the whole of the retina receives upon itself the images of external objects, and is highly susceptible of luminous impressions, the foramen centrale is incapable of luminous excitation by means of light of ordinary intensity, and it does not, as far as we know, assist the visual powers of the eye. Behind the cornea we find a coloured membrane

drawn across the eye; this membrane is called the

iris, (a Latin word for the rainbow,) and is the distinguishing feature by which the colour of eyes is determined, its anterior surface being in some animals richly and variously coloured. The iris is perforated nearly in its centre by the pupil”, which is a hole for the admission of light into the interior chambers of the eye; and it is a fact no less extraordinary than beautiful, that the iris is furnished with a self-adjusting apparatus, to which there is no parallel throughout the whole of human invention, by means of which the pupil is contracted or enlarged,

a: The Latin word pupilla signifies the ball, the apple or sight of e eye.

according as light is more or less abundant. In man this apparatus seems to be self-acting, and not to depend upon the will, except in a few rare cases, where individuals have been known to possess the power of spontaneously regulating the motions of the iris; but this power, like that by which a very few persons have been able to move about the outer ear, after the manner of some of the lower animals, seems lost to the great bulk of mankind. It will doubtless have been noticed, that on quitting a wellillumined room, where the pupil is small, that is, in its contracted state, in consequence of the abundant presence of light, and going out into a dark street, we are apt, at first, to suppose that the night is more than usually obscure; but, as we proceed, objects become more and more visible, and we are apt to exclaim, “It is not so dark as it was!" while, in all probability, the change, if any, is in the observer's own eye, since the fibrous arrangement which regulates the motions of the pupil, being relieved from the stimulus of a large quantity of light, gradually relaxes, and allows the pupil to expand, so as to admit as much light as possible in the obscure situation into which we now suppose it is transferred. It is believed that the motions of the pupil in the eyes of feline animals, such as cats, &c., and animals of prey generally, are voluntary; that is, they are regulated by the will of the animal, and serve the purposes of sudden and extraordinary adjustment, which may be required by the animal while engaged in its nocturnal pursuit after food. The iris divides the interior globe of the eye into two very unequal parts, or chambers; that before the iris is called the anterior chamber, and contains a limpid colourless liquid, called the aqueous humour, from its similarity to water, and the space behind the iris (which has been called the curtain of the eye, from the beautiful manner in which it seems to fold and unfold), is named the posterior chamber, and contains a small hard double convex lens, called the crystalline lens, (from its resemblance to crystal;) and the vitreous humour (from its similarity to molten glass), which completely fills up all the rest of the eye. The crystalline lens in its posterior, and most convex face, is exactly fitted to a concavity in the forepart of the vitreous humour; it is said to be enclosed in a transparent bag, called a capsula, and it is surrounded by what are termed the ciliary processes, which form an opaque circle round the lens, and impede all rays which might otherwise be transmitted by its side: the lens itself is composed of triangular pieces, which in their turn are formed of concentric scales. The substance of the lens increases in density: that is, its structure becomes more compact from the circumference to its centre, for the purpose of correcting what is called its spherical aberration f. The form of this lens varies in different animals according to their habits and places of abode. In the eye of the cod-fish it is spherical, and such of our readers as have seen a boiled cod's-head at table, will probably have noticed a white opaque ball in the eye of the animal; this is the crystalline lens of the codfish, which containing albumen, becomes of an opaque white, similar to the white of egg (which is almost pure albumen) when subjected to the heat of boiling water. The vitreous humour occupies the whole of the space between the crystalline lens and the retina. This humour is contained within cells, and resembles + The object of spherical lenses is to converge the rays of light to a point or focus, but in practice it is found that the rays deviate somewhat from this point, and this deviation is called spherical aberration; the latter term implies a wandering or straying. Two

causes are assigned to this phenomenon; 1st, the form of curvature of the lens; 2nd, the different refrangibilities of different rays of light.

(to use a rough analogy) honey contained in the cells of the honeycomb: this humour and the cells which contain it are both transparent. .

Having thus pointed out the principal parts of the eye and their uses, we may briefly allude to a few external appendages of the same organ. The bony projection of the eyebrows forms a sort of arched abode for the eye, to shield its delicate tenant from external violence, and from too much light; and, like a projecting roof, the brow is furnished with a ridge of hairs, the eyebrows, which arrest or entangle any small substances, solid or fluid, which might otherwise fall or trickle upon the eye. The eyelids, or semioval curtains which cover the great aperture of the orbit, graduate the light falling upon the eye by the extent of their separation, or exclude it when they are closed, although to a small extent light does enter at the line of junction of the two lids. The eyelashes are hairs which border the edges of the lids, arranged in three or four rows. Their direction is curved; those from the upper lid proceeding upwards, and those from the under lid downwards. Their length and fulness varies in different individuals; their colour is generally that of the eyebrow, and their purpose is that of an additional screen to the eye. The lachrymal ducts in which tears are secreted, in their usual healthy and natural state, supply the eye with moisture, which is spread over its surface by means of the eyelids: these ducts are situated a little within the nose.

REVOLUTIONS OF THE SEASONS.

. . . . . . . . . I solitary court
The inspiring breeze, and meditate upon the book
Of nature, ever open; aiming thence,
Warm from the heart, to learn the moral song.

PERsons of reflection and sensibility contemplate with interest the scenes of nature. The changes of the year impart a colour and character to their thoughts and feelings. When the seasons walk their round, when the earth buds, the corn ripens, and the leaf falls, not only are the senses impressed, but the mind is instructed ; the heart is touched with sentiment, the fancy amused with visions. To a lover of mature and of wisdom, the vicissitude of seasons conveys a proof and exhibition of the wise and benevolent contrivance of the Author of all things. When suffering the inconvenience of the ruder parts of the year we may be tempted to wonder why this rotation is necessary, why we could not be constantly gratified with vernal bloom and fragrance, or Summer beauty and profusion. We imagine that, in a world of our creation, there would always be a blessing in the air, and flowers and fruits on the earth. The chilling blast and driving snow, the desolated field, withered foliage, and naked tree, should make no part of the scenery which we would produce. A little thought, however, is sufficient to show the folly, if not impiety, of such distrust in the appointments of the great Creator. The succession and contrast of the seasons give scope to that care and foresight, diligence and industry, which are essential to the dignity and enjoyment of human beings, whose happiness is connected with the exertion of their faculties. With our present constitution and state, in which impressions on the senses enter so much into our pleasures and pains, and the vivacity of our sensations is affected by comparison, the uniformity and continuance of a perpetual Spring would greatly impair its pleasing effect upon our feelings. The present distribution of the several parts of the

year is evidently connected with the welfare of the whole, and the production of the greatest sum of being and enjoyment. That motion in the earth, and change of place in the sun, which cause one region of the globe to be consigned to cold, decay, and barrenness, impart to another heat and life, fertility and beauty. Whilst in our climate the earth is bound with frost, and the chilly smothering snows are falling, the inhabitants of another behold the earth first planted with vegetation and apparelled in verdure, and those of a third are rejoicing in the appointed weeks of harvest.

Each season comes attended with its benefits, and beauties, and pleasures. All are sensible of the charms of Spring. Then the senses are delighted with the feast that is furnished on every field and on every hill. The eye is sweetly delayed on every object to which it turns. It is grateful to perceive how widely, yet chastely, nature hath mixed her colours and painted her robe; how beautifully she hath scattered her blossoms and flung her odours. We listen with joy to the melody she hath awakened in the groves, and catch health from the pure and tepid gales that blow from the mountains.

When the Summer exhibits the whole force of active nature, and shines in full beauty and splendour, when the succeeding season offers its purple stores and golden grain, or displays its blended and softened tints; when the Winter puts on its sullen aspect, and brings stillness and repose, affording a respite from the labours which have occupied the preceding months, inviting us to reflection, and compensating for the want of attractions abroad by fire-side delights and home-felt joys. In all this interchange and variety we find reason to acknowledge the wise and benevolent care of the God of the seasons. We are passing from the finer to the ruder portions of the year. The sun emits a fainter beam, and the sky is frequently overcast. The garden and fields have become a waste, and the forests have shed their verdant honours. The hills are no more enlivened by the bleating of flocks, and the woodland no longer resounds with the song of birds. In these changes we see evidences of our instability, and images of our transitory state.

So flourishes and fades majestic man.

Our life is compared to a falling leaf. When we are disposed to count on protracted years, to defer any serious thoughts of futurity, and to extend our plans through a long succession of seasons, the spectacle of the fading, many-coloured woods, and the naked trees, affords a solitary admonition of our frailty. It should teach us to fill the short year of life, or that portion of it which may be allotted to us, with useful employments and harmless pleasures; to practise that industry, activity, and order, which the course of the natural world is constantly preaching.

Let not the passions blight the intellect in the spring of its advancement, nor indolence nor vice canker the promise of the heart in the blossom. Then shall the summer of life be adorned with moral beauty, the autumn yield a harvest of wisdom and virtue, and the winter of age be cheered with pleasing reflections of the past, and bright hopes of the future.—Monthly Anthology

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ON THE PLEASURE OF ACQUIRING KNOWLEDGE. In every period of life, the acquisition of knowledge is one of the most pleasing employments of the human mind. But in youth, there are circumstances which make it productive of higher enjoyment. It is then that everything has the charm of novelty; that curiosity and fancy are awake; and that the heart swells with the anticipations of future eminence and utility. Even in those lower branches of instruction which we call mere accomplishments, there is something always pleasing to the young in their acquisition. They seem to become every well educated - person; they adorn, if they do not dignify humanity; and, what is far more, while they give an elegant employment to the hours of leisure and relaxation, they afford a means of contributing to the purity and innocence of domestic life. But in the acquisition of knowledge of the higher kind,-in the hours when the young gradually begin the study of the laws of mature, and of the faculties of the human mind, or of the magnificent revelations of the Gospel, there is a pleasure of a sublimer nature. The cloud, which in their infant years, seemed to cover nature from their view, begins gradually to resolve. The world in which they are placed, opens with all its wonders upon their eye; their powers of attention and observation seem to expand with the scene before them; and, while they see, for the first time, the immensity of the universe of God, and mark the majestic simplicity of those laws by which its operations are conducted, they feel as if they were awakened to a higher species of being, and admitted into nearer intercourse with the Author of Nature. It is this period, accordingly, more than all others, that determines our hopes or fears of the future fate of the young. To feel no joy in such pursuits; to listen carelessly to the voice which brings such magmificent instruction; to see the veil raised which conceals the counsels of the Deity, and to show no emotion at the discovery, are symptoms of a weak and torpid spirit, of a mind unworthy of the advantages it possesses, and fitted only for the humility of sensual and ignoble pleasure. Of those, on the contrary, who distinguish themselves by the love of knowledge, who follow with ardour the career that is open to them, we are apt to form the most honourable presages. It is the character which is natural to youth, and which, therefore, promises well of their maturity. We foresee for them, at least, a life of pure and virtuous enjoyment; and we are willing to anticipate no common share of future usefulness and splendour. In the second place, the pursuits of knowledge lead not only to happiness but to honour. “Length of days is in her right hand, and in her left are riches and honour.” It is honourable to excel even in the most trifling species of knowledge, in those which can amuse only the passing hour. It is more honourable to excel in those different branches of science which are connected with the liberal professions of life, and which tend so much to the dignity and wellbeing of humanity. It is the means of raising the most obscure to esteem and attention; it opens to the just ambition of youth, some of the most distinguished and respected situations in society; and it places them there, with the consoling reflection, that it is to their own industry and labour, in the providence of God, that they are alone indebted for them. But, to excel in the higher attainments of knowledge,_to be distinguished in those greater pursuits which have commanded the attention, and exhausted the abilities

of the wise in every former age, is, perhaps, of all the distinctions of human understanding, the most honourable and grateful. When we look back upon the great men who have gone before us in every part of glory, we feel our eye turn from the career of war and of ambition, and involuntarily rest upon those who have displayed the great truths of religion, who have investigated the laws of social welfare, or extended the sphere of human knowledge. These are honours, we feel, which have been gained without a crime, and which can be enjoyed without remorse. They are honours, also, which can never die, -which can shed lustre upon the humblest head, and to which the young of every succeeding age will look up, as their brighest incentives to the pursuit of virtuous fame.—ALIson.

THE FEATHER OF A PEACOCK.

IN its embryo the feather of a peacock is little more than a bladder containing a fluid, while every one knows the general structure of those long ones which form the train. The star is painted on a great number of small feathers, associated in a regular plane; as those have found their way from the root, through this long space of three feet, without error of arrangement or pattern, in more millions of feathers than imagination can conceive. If this is sufficiently wonderful, the examination of each fibre of this canvass (to adopt this phrase,) will much increase the wonder. Taking one-half of the star, the places and proportions of the several colours differ in each of those, as do their lengths and obliquities, yet a single picture is produced, including ten outlines, which form also many irregular yet unvarying curves. And, further, the opposed half corresponds in every thing; while this complicated picture is not painted after the texture is formed, but each fibre takes its place ready painted, yet never failing to produce the pattern. If this is chance, the coloured threads of a tapestry might as well unite by chance to produce a picture; while every annual renewal is equally accurate, as it has been in every such animal since the creation. And whatever the other chances may be, enormous as they are against the hypothesis, this further number cannot be evaded, because it would be to abandom the very principle of chance, to say that renewal, or perpetuation, were governed by laws. If the system is to mean what it pretends to do, every feather that ever existed must have been the result of fortunate chances. This would be enough, had this object not demanded the arithmetical calculation; for, omitting all else, who would even hope to reproduce the star from the same separated materials, under any number of chances 2

But the entire analysis I need not make in words; it can be done by any one on the subject itself, and with a more satisfactory effect. Let him take each fibre separately, note the number of the colours, their gradations, the very different modes of those on the different fibres, and the very different places of those colours on them, with the still more remarkable differences in those fragments of the many outlines included in the star. The painter, who best knows the difficulty of producing gradations on even a fixed plane, will best also conceive the impossibility of producing, under any number of chances, such a coloured plane, from a hundred separated fibres previously painted, or even of thus producing the much easier outlines.

But who will compute this unwieldy sum ? The result alone, the figures expressing the chances against one, that this little object was not the produce of chance, would fill a page; it is equivalent to infinitude against one. Suffice it here, that I inquire of the probability of simply replacing, by chance, the disarranged and intermixed fibres of the star in their original places or order; while, even then, I need not take more than the half, as the result of the total is equally unnecessary and unwieldy. It would be a purposeless parade of arithmetic to detail those figures; if the reader will place a unit before sixty-four zeros, he will have a sufficient conception of these chances for the present purpose. And chances far short of this have ever been held competent to any proof. [Macculloch on the Attributes of God.]

THE MANUFACTURE OF GUN-FLINTS.

THE art of forming Gun-flints was formerly kept a profound secret, at least in France and Germany. The kind of stone employed, is that species of silex, or flint, which is found in irregularly shaped lumps in the chalk formations of the earth. The masses of flint which are best fitted for the purpose, consist of those of a convex surface, approaching to globular, the knobbed and branched flints being generally full of imperfections. The best flint nodules are in general from two to twenty pounds in weight; they should be unctuous, or rather shining, internally, with a grain so fine as to be imperceptible to the eye. The colour should be uniform in the same nodule, and may vary from honey-yellow to a blackish-brown; it is necessary that the fracture should be smooth and equal, and somewhat conchoidal, hollowed like a shell, and should be partially transparent at the thin edges. Four tools are necessary in the manusacture of

Fig. 1. Fig. 2.

flints. 1. An iron hammer, fig. 1, with a square head, not more than two pounds in weight, and seven or eight inches in length: 2. a hammer of well-hardened steel, fig. 2, with two points, a handle seven inches long, and from ten to sixteen ounces in weight: 3. a disk hammer, or roller, fig. 3, like a solid wheel or

Fig. 3. Fig. 4.

T

cylinder, two inches and one-third in diameter, and not exceeding twelve ounces in weight; it is made of steel not hardened, and has a handle six inches long. 4. a chisel, fig. 4, tapering and bevelled at both ends, which should be made of steel not hardened, six, seven, or eight inches long, and two inches wide. With these tools the flints are formed in the following manner:The workman, seated on the ground, places the nodule of flint on his left thigh, and applies slight strokes with the square hammer to divide it into smaller pieces of about a pound and a half in weight, with broad surfaces and an almost even fracture. He then holds the piece of flint in his left hand, not supported, and strikes with the pointed hammer on

the edges of the great planes produced by the first breaking, by which means the white coating of the flint is removed in the form of small scales, and the mass of flint itself laid bare, as shown in fig. 5; after

this he continues to chip off similar scaly portions from the pure mass of flints as AAA, fig. 6, which is a cross section or plan of fig. 5, the shaded portions showing the points removed at each blow. These portions are nearly an inch and a half wide, two inches and a half long, and their thickness in the middle is about one-sixth of an inch: they are slightly convex below, and consequently leave in the part of the flint from which they are separated, a space slightly concave, longitudinally bordered by two rather projecting straight lines or ridges. These ridges produced by the separation of the two scales, must naturally constitute nearly the middle of the subsequent piece; and such scales alone as have their ridges thus placed in the middle are fit for gun-flints. In this manner the workman continues to split or chip the mass of flint in various directions, until the defects usually found in the interior, render it impossible to make the fracture required, or until the piece is reduced too much to be easily broken.

To shape the gun-flint out of these scales, he selects such only as possess the requisite form ; to ascertain this, it is necessary to understand the parts to be distinguished in a gun-flint. These are five in number; A the sloping facet, B B the sides, c the back, D the under sur- b face, which should be rather con- -A- F No vex, and F the upper facet, between N_B : the tapering edge and the back. In

In order to fashion the flint, those scales are selected which contain at least one of the ridges F or A ; he fixes on any tapering border of the scale to form the striking edge; he then divides the scale into pieces, of the proper width of the flint, by means of his chisel; this tool is driven into a solid block of wood, with one of its edges upwards; that part of the flint is placed across this edge where the separation is intended to take place, and a blow from the roulette, or round hammer, on the upper surface, divides it as cleanly as if it were cut; the back of the flint is then made square by the same means.

The last operation is to trim or give the flint a smooth and equal edge; this is done by turning the stone and placing the edge of its tapering edge on the chisel, and striking it a few blows with the round hammer.

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