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1. THE PURIFICATION AND APPLICATION OF human things,) as I shall disclose to you these THE MIND. things with the fullest conviction, with the deep

2. THE LIGHT OF NATURE, OR METHOD OF IN- est forecast of my mind, and after the profoundest research into the present state of knowledge, in


3. NATURE ILLUMINATED, OR THE TRUTH OF the method of all others the most legitimate. THINGS.

C. I. Legitimate Mode of Statement.

"And what," you will say, "is this legitimate method? Have done with artifice and circumlocution; show me the naked truth of your design, I find, my son, that men in showing forth, and that I may be able to form a judgment for myno less in concealing the knowledge which they self." I would, my dearest son, that matters think they have acquired, have not acted in a were in such a state with you as to render this spirit of good faith and of duty. No less mis- possible. Do you suppose that when all the enchievous, though perhaps less shameful, is the trances and passages to the minds of all men are error of those who, with good intentions, but lit- infested and obstructed with the darkest idols, and tle wisdom, are ignorant of the art and rules these deep-seated and burned in, as it were, into proper for setting forth their several subjects. their substance, that clear and smooth spaces can We do not intend, however, to begin a complaint be found for receiving the true and natural rays of either this perversity or ignorance in the ex- of objects? A new process must be instituted, pounders of knowledge. Had they, by unskilful by which to insinuate ourselves into minds so enteaching, broken down the weight of the subjects tirely obstructed. For as the delusions of the taught, it might, no doubt, have been matter insane are removed by art and ingenuity, but agof just indignation. But, in teaching inaptitude, gravated by violence and opposition, so must we it was natural to expect absurdity. I, however, adapt ourselves here to the universal insanity. far different from such instructors, intend to im- What! do even those less difficult requisites perpart to you not fictions of imagination or shadows taining to the legitimate method of delivering of words; not a mixture of religion; not certain knowledge, appear to you such light and easy commonplace observations, or certain well-known matters? That it be ingenuous, that is, afford experiments adjusted to conformity with fanciful no handle or occasion for error; that it have a theories, but to bind, and place at your command, certain native and inseparable quality, both to nature with her offspring about her; and can this conciliate belief, and repel the injuries of time, so be supposed a theme fit to be debased by preten- that the knowledge so delivered, like a vigorous sion or unskilfulness, or other defective treatment. and healthy plant, may daily shoot and thrive; So may I exist, my son, and so may I extend the that it appear to place itself in, and adapt itself to now deplorably narrow limits of man's dominion the situation of its proper and reasonable reader: over the universe to the permitted boundaries, whether I shall show in the sequel all these qua(which is the only object of my prayers among | lities or not, I appeal to futurity.

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Or the generation of sound, and the first per- | customary, and as it were invariable, when trials cussion. and observations have grown into art, that the Of the lasting of sound, and of the perishing mathematic and practic is pursued, the physic is and extinction of sounds.

Of the confusion and perturbation of sounds. Of the accessory aids and impediments of sounds.

Of the stay of sound, and the diversity of mediums.

Of the penetration of sounds.

Of the carriage of sounds, and their direction or spreading, and of the area which sound fills, together and severally.

Of the variety of the bodies, which yield sound; and the instruments; and of the species of sounds which occur.

Of the multiplication, majoration, diminution, and fraction of sounds.

Of the repercussion of sounds, and echo. Of the consent and dissents of audibles and visibles, and of other (so called) spiritual species. Of the quickness of the generation and extinction of sound, and the time in which they are effected.

Of the affinity or non-affinity which sound hath with the motion, local and perceptible, of the air in which it is carried.

Of the communication of the air percussed and elided, with the ambient air, and bodies, or their spirits.

left. Moreover, optic fareth some whit better; for not only the art of painting, and beauty, and symmetry are propounded unto optic, but the contemplation of all visibles; but unto music, only musical tones. Therefore we do inquire of sounds.

Of the Generation of Sound, and the First Percussion.

The collision, or elision, as they speak, meaning thereby some section or cutting of the air, which they will have to be the cause of sound, imports neither the form, nor the secret process of sound, but is a term of ignorance and superficial contemplation.

Sound is diffused and moves with so small an impulse in its generation; also so far, and that in round, not much depending on the first direction; withal so smoothly, without any evident motion, found either by flame, or by feathers and straws, or in any other manner; that it seems altogether hard that the form of sound should be any cutting, or local and perceptible motion of the air, howsoever this may hold the part of the efficient.

For that sound is so suddenly generated, and straightway dies, it seems necessary that either its generation do a little thrust the air from its nature, and its perishing restore it, as in the compressions of waters, whereas a body cast into the

Of the forming or articulation of sound.
Of the very impression of sounds upon the water makes many circles in the waters, that


come of the water at first compressed, afterward

Of the organ of hearing, and its disposition and restoring itself into its proper consistence and diindisposition, helps, and hindrances.

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mension; (which we have used to call the motion of liberty;) or that, contrariwise, the generation of sound be an impression pleasant and kindly, that winneth upon the air, and whereunto the air freely stirreth itself, and that its extinction be from some enmity, which suffers not the air longer to enjoy that agitation and impression; as in the generation of the very body of flame, wherein the generation of the flame appears to be made with alacrity, but by the air and other environing adversaries presently to be destroyed.

The whistling which is made by the mouth,

Instances of the percussion of a hard body against the air, are seen in musical stringed instruments; in the whistling of an arrow, as it flies through the air; in the beating of the air, although it strike not any hard body; also, in regals, their sound is given by the air striking against water; in the pipe they call the nightingale-pipe, which gives a sound continually tumbling; in water agitated and restoring itself again; and in the toys wherewith children please themselves, (they call them cocks,) in imitation of the voices of birds; likewise in other hydraulics.

without use of a whistle, may be effected by suck- | back of the hand, or upon the forehead, cracks by ing in of the breath toward the inner parts of the eruption of the air. mouth, not only by expelling of the breath outwards; and clearly all sucking of the air inwards gives a sound, which seems exceeding worthy of remark: because the sound is generated against the perceptible motion of the air, so as the first impulsion of the air appears plainly to be the remote efficient, and no part of the form of sound. In like manner, if there be an egg of glass taken, and the air through a small hole forcibly sucked out; then the hole stopped with wax, and it be laid by for a time; if afterwards the wax be removed from the hole, you shall hear plainly the hissing of the air entering into the egg, being drawn, to wit, by the inner air, after forcible rarefaction, restoring itself. So as in this trial also, sound is generated contrarily to the perceptible motion of the air.

In like manner, in the toy that is called a jew'sharp, holding the sides betwixt the teeth, the little tongue of iron is drawn outwards and jarred, when it flies back inwards against the air that is in the mouth, and thence is a sound created.

And in these three trials it may not be doubted but that sound is generated by the percussion of the air inwards towards the mouth on the egg of glass.

Sound is generated by percussions. The percussion is either of air against air, or of a hard body against the air, or of a hard body against a hard body.

The instance of the percussion of air against air chiefly prevails in the human voice, and in the voices of birds and of other animals; next in musical wind instruments; also in ordnance, greater and less, where the percussion that gives the sound is generated chiefly by the percussion of the confined air that issues from the mouth of the piece against the outer air; for the bullet wherewith it is charged makes not much to the noise. Neither is the percussion of a soft body against a soft body only seen in the percussion of air against air, but also of air against flame, as in the raising of a flame with bellows; also flames amongst themselves, when one drives another, yield a certain roaring; but whether the air assist here may be further inquired. Also, all flame that suddenly taketh, if it be of any greatness, makes a sound, rather, as I think, in displacing of the air than of itself. Also in eruptions, there is percussion made of the spirit breaking out against the air adjacent; as in the cracklings made by dry leaves, or bay-salt, and many other things, when cast into the fire; and in thunder, either by the spirit oreaking out from the cloud, or wallowing and tossed to and fro, as in the more hollow and lengthened rolling of thunder; also we see in sport, that a fresh rose-leaf gathered together so as it shall contain air, and struck upon the

Instances of the percussion of a hard body against a hard body, are found either simply, or with communication of some air enclosed beside that air, which is cut or elided between the hard bodies percussed; simply, as in all hammering or knocking of hard bodies, with communication of air penned in, as in bells and drums.

A stone cast forcibly into the water gives a sound; as do the drops of rain falling upon the water, and no less wave dashing against wave, in which there is percussion betwixt a hard body and water.

It seemeth to be constant in the generation of all sound, that there are certain parts of air, and that air is required between the bodies percussed; which air, in the percussion of a hard body against the air, and of a hard body against a hard body, appears manifestly to be cut or elided. I judge that flame should suffice for this in the stead of air, as if in the midst of a great flame a bell should be rung, or stones knocked together; but in the percussion of air against air this elision or separation appears more dark, but the air seems only to be beaten and driven, and that in a soft voice, very gently. But it seems, even in this kind, to need that there be some elision of the air percussed by the air percussing: for even in air moved by a fan, the air from the side of the fan, and when air is blown out of bellows, the blast of air from the mouth, divides the other air. But concerning this kind of elision of the air, which happens when the percussion of air against air createth sound, as in the voice, let inquiry be made further.

It is well doubted, whether the percussion that produces sound, when the air is percussed by a string, or otherwise, be from the beginning, when the string starting back percusses the air, or a little after, the air, to wit, being compressed by the first percussion, and thereafter acting the part, as it were, of a hard body.

When sound is yielded by the percussion of air against air, it is required that there be an imprisoning or penning of the air in some concave, as in whistling by the mouth, in pipes, in the viol, in the voice; which is divided, where

the air is penned in the hollow of the mouth or throat. In the percussion of a hard body against air is required hardness of the body and quick motion, and sometimes communication with a concave, as in the cittern, lute, beating of the air, &c.; but in the percussion of a hard body against a hard body, the hollow, or the quick motion, is less required.

There is a talk of a white gunpowder, which should give percussion without noise. It is sure that nitre, which is white, is of great force for expulsion, yet in such wise as the speedy kindling doth much enhance both the percussion and the noise; but the quick kindling is caused specially by the coal of willows, which is black. Therefore, if a composition were made of sulphur and nitre, and a modicum of camphor, it is like that the kindling would be slower, and the percussion not so jarring and sharp; whence much might be diminished of the sound, but with loss too in the strength of the percussion. To be further inquired.

It can be taken for an argument, that sound is manifestly some kind of local motion in the air. that it so suddenly fails; because, in all cutting or impulsion of the air, the air quite recovers and restores itself, which also water doth through many circles, albeit not so speedily as the air.

Of the Confusion and Perturbation of Sounds. In the act of sight, visibles from one part impede not visibles from other parts; but all the visibles which offer themselves from every part, lands, waters, woods, the sun, buildings, men, are at once represented to the eyes. But, if so many voices or sounds did at once issue from several parts, the hearing should be plainly confounded, nor might distinctly perceive them.

The greater sound confoundeth the less, that it should not be heard; but spiritual species, as they speak of a diverse kind from sound, confuse not sound, but altogether and at once hang in the air, the one little or nothing troubling the other; as light, or colour, heat and cold, smells, magnetic

Of the Lasting of Sound, and its Perishing and virtues; all these together can hang in the air, nor


The lasting of the sound of a bell that is struck, or of a string, which seems to be prolonged, and gradually to fade, comes not rightly of the first percussion, but the trembling of the body percussed generates in the air continually new sound. For, if that trembling be checked, and the bell or string stayed, the sound quickly dies; as in virginals, where, if the quill be dropped so that it touch the string, the sound ceases.

A bell hanging in the air gives a far louder and more enduring sound if it be chimed upon with a hammer on the outside, than if it stood fixed, and were in like manner chimed upon with a hammer. And of the more enduring sound the reason is rendered already, because it trembleth longer. But that even the first sound in the hanging bell is more resounding, in the standing less, would be further inquired.

Likewise a drinking cup of silver or of glass that is fillipped, if it be left alone, gives a sound louder and more lasting; but if the foot of the cup be steadied with the other hand, a far duller, and of shorter stay.

The sound which is yielded in the viol or cittern is plainly not made by the percussion between the finger, or the quill, and the string, or between the finger, or the quill, and the air, but by the finger impelling, and thereafter the string flying back, and in that recoil percussing the air. Therefore, when the string is moved with a bow, not by the finger, or a quill, the sound can be continued at pleasure, through the roughness of the string of the bow, which is a little smeared with rosin; whence it slides not on the string, nor once strikes it, but holds and continually tortureth it, out of which motion the sound is maintained. VOL. III.-68

yet do greatly hinder or disturb sounds.

The cause wherefore many visibles are at once represented unto the eyes, the one not confounding the other, would seem to be none other but this: that visibles are not seen except in a right line, but sounds are heard even in a line oblique, or arcuate. Therefore, as many objects in the area of the sphere of sight, as are conveyed, there be so many cones of beams, nor ever one cone doth coincide with another; neither do the vertices of the cones meet in the same point, because they are carried by right lines. But sounds, which are carried by lines, both right and arcuate, can meet easily in one point, and so are confused. The same seemeth to be the cause wherefore a more bright colour drowns not a more dim colour; nevertheless, a greater light obscures and hides a weaker light, because light is perceived in an arched line, like as sound. For, although the very flame of a candle be not seen except in a right line, yet does the light that is everywhere spread round attain to the sight in lines, arched in respect of the body of the candle: the like is the case of the sun, or flame. Now, if it be objected that neither is light itself seen except in a right line from air illuminated, it is true; but I think that this as well happens to sound: for neither is sound heard unless in right lines from some part of the sphere of sound, whither the first pulsation arrives. But colour, which is nothing other than the image unequally reflected of the light, spreadeth around so weak species, that it little or nothing tinges the air adjacent, unless where the colours are conveyed in right lines between the object and the eye.

Let there be a trial made with a double recorder, in which let there be two fipples, at each end one, so as they may be played in unison: the hollow

pipe being of a double length, and continued in | ness; and let this be distinctly inquired, not only one; let two together play the same tune at either whether they hear any sound at all from above. end, and let it be noted whether the sound be confused, or amplified, or dulled.

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To inquire, which bodies, and of what solidity and thickness, altogether debar and shut out sound; as, also, which more or less dull, although they intercept it not wholly. For as yet is it not known which mediums interposed be more propitious, which more adverse. Therefore, let there be trial made in gold, stone, glass, cloth, water, oil, and of the thickness of each. Hereof is all need to inquire further.

Air is the aptest, and, as it were, the sole medium of sound. Again, the moister air (I judge) better conveyeth sound than the drier; but in a fog what happeneth I remember not. Also, the night air better than by day; but this can be

ascribed to the silence.

Inquire touching the medium of flame, what its operation shall be in respect of sound; whether, to wit, a flame of some thickness altogether stop and intercept sound, or at least deaden it more than the air. This can be seen in bonfires.

Also, to inquire concerning the medium of air vehemently agitated. For, although wind carry sound, yet I deem that any vehement wind doth somewhat trouble sound, so as it shall be heard less far, even with the wind, than in still weather, of which let there be more inquiry made.

To see what sound brass or iron, red-hot, yields, struck with a hammer, compared to that which it gives cold.

Of the Penetration of Sounds.

The aëtites, or eagle stone, hath like a kernel or yolk of the stone, which being shaken makes a flat sound; so a hawk's bell, [stopped,] but a much clearer if there be a chink.

Let inquiry be made of divers, if they hear at all under water, especially that is of any deep

which is made in the air, but also, whether they hear the percussion of the body of the water within the water, where no air is. I have made this trial in a bath; a pail of a good size with the mouth turned over was, in such wise, pressed evenly down, as it carried the air fairly down with it, in its hollow, below the water, to the depth of a hand-breath; and in this manner the pail was held down with the hands, that it should not overturn nor rise: then a diver put his head within the pail, and did speak: his voice was heard, speaking; and even his speech was articulately distinguished, but wonderfully shrill, and almost like a whistling, as the voice useth to be heard in a play of puppets.

Let it be exactly inquired, so as it be clearly rendered positive whether sound can be generated, except there be air betwixt the percussing and the percussed body. As, if two pebbles hanging by a string be let down into a basin of water, or a river, and shaken, so as they shall strike together in the midst of the water; or let an open pair of tongs be thrust down into the water, and there knapped; and let it be noted whether they give a sound, and what. I do suppose that divers, in swimming, make no noise under the water; unless there may perchance be some, by the succession of motion under the surface of the water, and the water thence striking the air.

There is no doubt but in bladders tied, and not quite full, and shaken, there is a sound given, namely, of the liquor contained in them, and no less a sound is given on letting down a stone into water, when it strikes the bottom of the vessel. But in the former trial air is intermingled; in the second, the percussion of the bottom of the vessel by the stone communicates with the air without the vessel. But, after the first percussion, it needeth not that there be air intermediate through the whole area of the sphere deferent; for that is shown by the trial of one speaking in a pail under the water, where part of the deferent from the water is not air, but the wood of the pail, and the water; whence the sound is sharpened, and minished, and lost.

But, because it is manifest that sound passes through and penetrates hard bodies, (as potters' earth and glass;) and it is also most certain (although hitherto concealed from men's observation) that there is, in every tangible body, some pneumatical part, besides the gross parts intermixed, it is to be considered whether penetration of sound of this kind come not thence, for that the pneumatical or aerial parts of the tangible body communicate with the outer air.

Take a vessel of silver, and another of wood, full of water; take a pair of iron tongs, and knap them in the water in the vessels, at the distance of a thumb's breadth, perhaps, or more, from the

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