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smell and to odours grateful and offensive in the case of animals. But the capacity of touch and taste, like a prophet and interpreter, delivers to the mind all the modes either of forcible appeal, or of benign and insinuating flattery to the sense, which are incident to inanimate substances, and all the forms they assume under the influence of these affections. For compressions, expansions, corrosions, separations, and the like, are, in things without life, invisible in their progress, and are not perceived till the effect is manifest. But all violence to the organization of animals is accompanied with a sense of pain, according to their different kinds and peculiar natures, owing to that sentient essence which pervades their frames. And from this principle may be inferred the knowledge whether haply any animal possesses some additional sense, besides those commonly observed, and what senses and how many can possibly exist in the whole circle of animated nature. For from the affections of matter duly analyzed, will follow the number of the senses, if there be only the sufficing organs for the operation of such senses, and the presence of spirit to inform them.

Of violent Motion, that it is the rapid Motion and Discursation of the Particles of a Body, in consequence of Pressure, but perfectly invisible.

VIII.

Violent motion, (as it is termed,) by which missiles, as stones, arrows, cannon balls, and the like, move through the air, is of all descriptions of motion nearly the most familiar. And we may note here, the singular and supine indifference which men have discovered in observing and investigating this kind of motion. Nor is a faulty way of tracing the nature and power of it attended with only trivial loss; since it is of unlimited use, and as it were the life and informing principle of projectiles, engines, and all the applications of mechanical power. Yet many conceive that they have completely acquitted themselves of their part in the investigation, if they but pronounce such motion to be violent, and contradistinguish it from natural. And no doubt it is the system of Aristotle and his school, to instruct men what to say, not what to think; to teach a man by what devices of affirming or denying, he may get clear of a disputant in argument, not how, by force of thought, he may get clear of a difficulty in the conviction of his own mind. Others, rather more attentive, laying hold of the position that two bodies cannot exist in one place, say that it follows as a consequence that the stronger body propel, and the weaker be dislodged: that this dislodging or flight, if a less force is used, continues no longer than the duration of the original impulse, as in protrusion; but if a greater, the

impulsion continues for a time, even after the removal of the impelling body, till it gradually slackens, as in throwing. And here, again, according to another inveterate habit of the same school, they catch only at the commencement of the thing, indifferent to its progression and termination, and drag in all that follows under the head of the beginning; whence, with an overweening haste and impatience, they break off their train of thought in the midst. For in what they say of bodies giving way at the impelling force, there is something; but why the motion should continue after the urging body is withdrawn, and consequently the necessary alternative of the weaker and stronger body mingling is at an end, of this they say nothing, not sufficiently apprehending the scope of their own observations.

Others, however, more attentive and steady in investigating, having marked the force of the air in winds and the like instances, which is capable of throwing down trees and towers, have supposed that the force which urges and accompanies projectiles, after the first impulsion, ought to be referred to the air accumulating and rushing in behind the body in motion, by the impulse of which that body is borne along, like a ship in the expanse of water. And such persons, at least, do not quit their subject, but carry their thought to its conclusion; yet they, nevertheless, do not attain to the truth. The cause in reality is this. The principal motion seems to be in the parts of the volant body itself, which parts being imperceptible to vision, on account of their extreme tenuity, escape the notice of men, not sufficiently attentive to their subject, and passing it over with a cursory glance. But to one who gives it a sounder examination, it is clearly evident, tha. the harder bodies are, they are the more impatient of pressure, the more acutely sensitive to it, as it were; so much so, that if disturbed ever so little from their natural position, they endeavour with great velocity of movement to free themselves from its effect, and resume their original state. To effect which, the several parts, beginning with the part struck, successively propel one another, in the same way as an external force, and keep up that motion vigorously; hence results a continuous and, though invisible, intense vibration of the parts. And this we see exemplified in glass, sugar, and similar brittle substances, which, it they be divided by a blade or edged instrument, are, as it were, in a moment broken down in other parts distant from the line described by the blade. Which evidently proves that the motion of pressure travels to the parts of these substances successively. This motion pervading all the parts of the body, and trying, as it were, their compactness, causes the breaking down of that part, where, from the structure, the cohesion is weak. Yet does not this motion, though it agitates and

2 M 2

permeates the whole, come into view, till a visible of the cause of Motion in Fire-arms, which has been

break or divulsion of continuity takes place. Again, we observe, if we happen to bend and compress between the thumb and forefinger the two ends of a wire, or bit of cane, or the harder part of a pen, (or similar bodies which unite flexibility with a certain degree of elasticity,) they anon spring from the hand. The cause of which motion is evidently discernible not to be in the extremities compressed by the fingers, but in the middle part, which is the seat of forcible pressure, to relieve itself from which, the motion comes into play. And in this instance it is clearly shown, that the alleged cause of motion, the impulsion of the air, is inadmissible. For here there is no concussion to let in a rush of air. This is also proved by a slight experiment, when we press the fresh and smooth ball of a plum, drawing the fingers gradually together, and in this manner let it go. For in that instance also compression is substituted for percussion. But the most conspicuous effect of this interior motion is in the revolutions and gyrations of missiles while flying. The missiles, indeed, proceed onwards, but they make their progression in spiral lines, that is, by straight-lined and rotatory motion together, and indeed this curvilinear motion is so fleet, and at the same time so easy, and somehow so familiar to things, as to excite a doubt in my mind whether it does not depend on some higher principle. Yet I think that the cause of this fact is no other than the same we are now handling. For the concussion of the body occasions an excessive impetus in all its parts and particles, to effect in some way or other their extrication and freedom. The body, therefore, not only acts and flies forth in a straight line, but strives to move from every point in it at once, and, therefore, whirls round; for in both ways it somewhat relieves itself of its impuise. Now this, which in the harder solids is a somewhat recondite and latent property, is in the softer ones evident, and, so to speak, palpable. For as wax, and lead, and similar soft bodies, when struck with a mallet, give way not only in the line of percussion, but laterally every way; so, in like manner, hard or resisting bodies move in a straight line and periphery at once. For the retrocession of soft bodies in their substance, and of hard ones in their place, is the same in its principle, as is evidently seen in the structure of the soft body, and in the affection of the hard one, exhibited in its flight and volant path. Meantime | let none think that besides this motion, (which is the cardinal point,) I do not ascribe a certain degree of effect to the conveyance of the air, which is capable of assisting, obstructing, modifying, and regulating the principal motion; for its power is far from being inconsiderable. And this doctrine of violent or mechanical motion (which has been hitherto unknown) is, as it were, the fountain-head of practical mechanics.

hitherto investigated only in part, and that part comparatively unimportant.

IX.

The theory of fire-arms-of a motion so powerful and so remarkable, is imperfect, and, in the more important part, defective. For it is said in explanation that the gunpowder, after having been converted into flame and volatilized, expands and occupies more space; whence it follows, that as two bodies cannot exist in the same space, otherwise a jumbling of their dimensions would ensue, or the elementary form be destroyed, or a preternatural arrangement of the internal parts of the body be the effect, (for this is what they say,) that the impeding body is ejected or broken. And what they say contains something. For this tendency is both an affection of matter, and an ingredient in the motion itself. Yet they err in this, that in their over hasty way of determining, they jump at once to the necessary consequence of the dilatation of a body, and do not accurately consider what comes first in the order of nature. For that the substance of the gunpowder, after having been converted into flame, must occupy a larger space, is doubtless a thing of necessity; but that the substance of the gunpowder should be inflamed at all, and that so instantaneously, is not determined by a like necessity, but depends on an antagonism, and comparative force of motions. For there is not a doubt, that the compact and heavy body which is expelled or dislodged by this motion, offers considerable resistance before it gives way, and, if it happen to be the stronger, is victorious; that is to say, the flame, in that case, does not cast out the ball, but the ball stifles the flame. If, therefore, instead of gunpowder, you take sulphur, asphaltum, or the like, bodies which are also quickly inflammable, and (as the closeness of particles in bodies hinders ignition) reduce them to a grain like gunpowder, mixing up with it a small quantity of the ashes of the juniper, or some other very combustible wood; yet, should the nitre be wanting, that rapid and powerful motion does not follow: the motion to perfect inflammation is impeded and fettered by the resisting body, so that it cannot fully expand and take effect. For, besides the motion of inflammation, which chiefly arises from the sulphureous part of the gunpowder, there is yet another powerful and violent motion in the case. This is caused by the crude watery ether, which is extricated from the nitre in part, but chiefly from the charcoal, and which not only itself dilates, as exhaled essences are wont to do, on the application of heat, but at the same time (which is the principal circumstance) by a motion of extreme rapidity, flies off and breaks forth from the heat and flame, thus distending and opening passages for the inflam mation to follow. Of this motion we see the

simplest form in the crackling of the dry leaves of laurel or ivy, when we cast them into the fire, and still more in salt, which approximates more nearly to the substance under examination. We also often observe something like this in the tallow of candles when melted, and in the windy rustle of green wood set on fire. But it is chiefly discernible in quicksilver, which is an extremely crude substance, not unlike the water of a chalybeate spring; and the force of it, if tried by the application of fire, and prevented from egress, not greatly inferior to that of gunpowder itself. Men ought, therefore, to be admonished and conjured from this example, not in their investigation of causes to catch at only one element, and so too lightly to pronounce upon them; but to look around them with caution, and rivet their contemplation more intensely and profoundly.

Of the dissimilarity of things celestial and sublunary, in regard to eternity and mutability, that it has not been proved to be true.

were,

X.

such a prodigious interval, what operations, movements, and changes presented themselves on the face of the globe, in engines, plants, animals, and so on, which on account of their distance would not equal the bulk of the minutest straw. Now, in bodies of such immense bulk and magnitude, that by the vastness of their dimensions they can overcome the greatness of distance, and come into visibility; it is evident from certain comets, that changes take place as they move in the expanse of the heavens. I allude to those comets, which have retained a certain unvaried relation of position to the fixed stars, such as that which in our own day appeared in Cassiopea. But as respects the earth, after having penetrated into the interior recesses of it, leaving that crust and mixture of substances which composes its surface and contiguous parts, there seems to exist there also an eternal immobility, analogous to that supposed to be found in heaven. For it is beyond a doubt, that if the earth underwent changes at an extreme depth beneath its surface, the influence of such changes, even in the region we tread, would produce greater calamities than any we behold. Most

not rise from a great but a very moderate depth, since they affect such an inconsiderable part of the surface. For in proportion as such visitations agitate a wider area of the earth's surface, in the same proportion we are to suppose that their bases and primitive seats enter deeper into the bowels of the earth. These earthquakes, therefore, which are greater, (in the extent of surface agitated I mean, not in violence of tremefaction,) and which but rarely happen, may be assimilated to comets of the description we have mentioned, which are also unusual. So that the proposition with which we set out remains unshaken, namely, that between heaven and earth there is no great difference as respects stability and change. But if any one is influenced to a different opinion by the regularity and seeming exactness of the motion of the

The received opinion that the universe is regu-earthquakes, certainly, and volcanic eruptions, do larly divided and discriminated by spheres, as it and that there is one system of heavenly and another of sublunary being, appears to have been adopted, not without rational grounds, provided the opinion is applied with proper modifications. For there is no doubt that the regions situated beneath the lunar orb, and above it, differ in many and important respects. Yet is not that belief more certain than this other, that the bodies in both spheres have tendencies, appetencies, and motions which are common to both. We ought then to imitate the unity of nature, to discriminate those spheres rather than rend them asunder, and not break down the continuity of our contemplation. But with respect to another received opinion, that the heavenly bodies undergo no change, but that the terrestrial or elementary (as they are called) are subject to change; and that the mat-heavenly bodies, we have before us the ocean, the ter of the last resembles a courtezan ever seeking the embracement of new bodies, but of the other a matron linked to one in stable and inviolable union; it seems but a popular notion, weak, and originating in appearances and superstition. This notion appears to be tottering, and without foundation, when viewed in either way. For neither does their imagined eternity consist with heaven, nor their mutability with earth. For, with respect to heaven, we cannot rest upon it as a reason for changes not happening there, that they do not emerge to our view, the view of man being prevented no less by distance of place than by tenu-plants, minerals, as a surface or cuter integument ity of bodies. For various changes are found to take place in the air, as is evident in heat, cold, smells, sounds, which do not fall within the line of sight. Nor, again, I suppose, would the eye, if placed in the orb of the moon, descry across

solitary handmaid as it were of eternity, which exhibits no less unchangeable uniformity than they. Lastly, if any one shall still insist, that nevertheless it cannot be denied, but that on the surface of the globe, and the part contiguous to it, changes innumerable take place, but that in heaven it is not so, we would have him thus answered; that we do not carry the parallel through every part; and yet if we take the upper and middle regions of air (as they are termed) for a surface and exterior integument of heaven, just as among us we regard that space over which are distributed animals,

of earth, we behold in both manifold reproductions and vicissitudes, in full operation. It would, therefore, seem that all the disorder, contention, and commotion of the universe, has its seat on the frontiers of heaven and earth alone. As in civit

society, it often happens in the ordinary course of | ness in heaven," it is also said that "generations things, that the borders of two adjacent kingdoms pass away, but the earth abideth for ever." And

are wasted with a perpetual succession of inroads and affrays, while the interior provinces of either kingdom enjoy continued and profound tranquillity. And none who bestows a proper attention on the subject will make an objection of religion. For it was only a heathen flourish to ascribe to a material heaven the quality of being impregnable to decay. The sacred Scriptures ascribe eternity and destructibility equally to heaven and earth, though they assign to them a different glory and an unequal reverence. For if it be recorded, that "the sun and moon bear faithful and eternal wit

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THE

THEORY OF THE FIRMAMENT.

BUT as so many foiling inconveniences are bodies that are simple and perfect, not of such as found to spring up on all sides, it should be deemed satisfactory if any thing can be avouched less revolting.

are compounded and imperfectly mixed,) are clearly those two bodies, air and flame. But these are to be propounded as bodies utterly heterogeneous, not, as is commonly supposed, that flame is nothing else than air set on fire. To these correspond, in the higher regions, the ethereal and sidereal nature, as, in the inferior, water and oil, and in the still deeper parts, mer

Let us, therefore, construct a scheme of the universe, according to that measure of history hitherto known to us, reserving for our future judgment all new lights, after history, and through history, our philosophy, by induction, may have reached a maturer age. But we will, in the out-cury and sulphur, and generally crude and fat set, premise some points that have reference to the matter composing the heavenly bodies, whence their motion and formation may be better understood; afterwards setting forth our thoughts and ideas of that motion itself, the chief subject under discussion.

Nature, then, in the separating of matter, seems to have drawn an impassable bar between the rare and dense, and to have assigned the globe of the earth to the order of the dense; but every thing, from the very surface of the earth, and its waters, to the utmost extremity of the firmament, to that of the rare or volatile, as it were, to twin classes of first principles, not indeed of equal but of suitable portions. Nor indeed does either the water clinging to the clouds, or the wind pent up in the earth, disarrange this natural and appropriate position of things: but this difference, between rare or volatile, and dense or tangible, is entirely primordial or essential, and is what the system of the universe chiefly has recourse to. It proceeds from a state of things the most simple possible this is from the abundance and scarceness of matter, in proportion to its extension. What belong to the order of subtile or volatile, as found here among us, (we are speaking of those

bodies, or, in other words, bodies that have a repugnance to, and such as are susceptible of, flame; (for salts are of a compounded nature, consisting of crude and at the same time also of inflammable parts.) It is now to be seen by what compact these two great families of things, air and flame, shall have occupied by far the greater part of the universe, and what are those parts they hold in the system. In air nearest to the earth, flame lives but a momentary life, and utterly perishes. But after the air has begun to be more depurate from the effluviæ of the earth and well rarefied, the nature of flame through various* adventures explores its way, and tries to take its station in the air, and after a time acquires some duration, not from succession, as with us, but in identity; which takes place for a time in some of the feebler comets, which are in a manner of an intermediate nature between a successive and a fixed flame; the flamy nature, however, is not fixed or established, before its arrival at the body of the moon. There the flame lays down

* Per varios casus, per tot discrimina rerum, Virg. Æn. iii 208. Per varios casus tentat et experitur,' may be translated, 'after various adventurous efforts tries,' or, 'adven

turous through many casualties tries.'

† Identitus: quævis actio repetita.

subdued, and assimilated, so as to thoroughly endure and become subservient to the sidereal. Wherefore, from the earth to the summit of the firmament are found three genera of regions, and, as it were, three stages, as relate to the region in which flame is extinguished, the region in which flame disperses itself; moreover, to quibble about contiguity and continuity in soft and flowing bodies, would be an utter vulgarism. Nevertheless, that point should be understood, namely, that nature is accustomed to advance to spaces by gradual steps, then, of a sudden, by leaps, and to alternate this sort of process, otherwise no fabric

sible degrees; for what a jump as respects the expansion of matter is there from water to air, even ever so dense or clouded, and yet these bodies, so different in their nature, are joined together in position and superficies without any medium or interposing distance: nor is it a less leap as to a substantial nature, from the region of the air to the region of the moon; in like manner, a prodigious one from the firmament. Wherefore, if any one shall have taken for continuous and contiguous, not from the manner of their annexation, but from the diversity of the bodies connected, those three regions we have spoken of, they can only be held for contiguous in their limits.

its extinguishable part, and protects itself on all sides, but yet it is a flame, weak without vigour, and having little of radiation of that kind; that is, neither vivid from its own nature, nor much excited by a contrary one; neither is it sincere, but, from its composition with an ethereal substance, such as is there met with, it is stained and mixed up. And in the region of Mercury flame has not very plentifully established itself, since, by the accumulation of its whole amount, it is able to form only a small planet, and that withal labouring and struggling, like an ignis fatuus, with a great and highly disturbed diversity of fluctuating motions, and not bearing to be sepa- | could be formed did she always proceed by insenrated but for a small distance from the guardian protection of the sun. Moreover, after we arrive at the region of Venus, the flamy nature begins to gain strength and to wax brighter, and to be collected into a globe of a tolerable size; nevertheless, she also is the handmaid of the sun, and shudders with an abhorrence of any greater recession from him. But in the region of the sun, flame is set, as it were, on a throne, the mean being among the flames of the planets, for there it is stronger and more glittering than the flames of the fixed stars, on account of the greater restraining* influence shed all around, and the closest possible union. But flame in the region of Mars is observed to be likewise powerful, denoting by its splendour the sun's vicinity, yet existing of its But now it is time to notice, in a clear and exown proper virtue, and admitting of a separation plicit manner, the amount and nature of what this from the sun to the extent of the whole diameter our theory, relating to the substance-matters of a of the firmament. In the region of Jupiter, how-system, may establish, as also of what it may ever, flame, laying aside, in a gradual manner, give the negative to, in order that it may be mainthis emulation, appears more serene and clear, tained or overthrown. It denies that vulgar not so much from its proper nature, (as the planet opinion, that flame is air ignited, by affirming that Venus, she being more sparkling,) but from being those two bodies, air and flame, are clearly heteless moved and excited by the nature spread rogeneous, like water and oil, sulphur and meraround him;† in which region it is probable that cury. It negatives that vacuum coacervatum held takes place, which Galileo devised, to wit, that by Gilbert, to obtain among the scattered spheres, the firmament there begins to be studded with but affirms that the spaces are filled with aerial stars, although from their minuteness invisible. or a flamy nature. It denies that the moon is an But, again, in the region of Saturn the nature of aqueous, or a dense, or a solid body, but affirms flame seems to become somewhat languid and that it is of a flamy nature, though it be gentle faint, as being both farther removed from an alli-withal, and weak, being indeed the first rudiment ance with the sun, and exhausted by the neigh- and the last sediment of celestial flame; since bouring constellated firmament. Lastly, a flamy | flame, (according to its density,) no less than air and sidereal nature having overpowered the ethereal nature, gives a constellated firmament composed of an ethereal and sidereal nature, as the globe of the earth is of continent and waters scattered up and down on this side and that side, the ethereal substance being however overruled, * Antiperistasin : εpísaσts signifies, generally, 'circumstance: but, in Athen. 1. 5, it also denotes circuitus: ai δὲ τῆς περισάσεως θύραι τὸν ἀριθμὸν ἔικοσι οὖσαι, portæ, quæ in circuitu erant, viginti, &c.; therefore, the illustrious author may mean by 'antiperistasis,' the attractive influence of the sun opposed to, and which detains [cohibet] the

planets in their orbits.

+ Or," from the nature spread around him being less," &c.,

according as irritata and exasperata are taken in the nominative or ablative case.

VOL. I.-53

and liquids, admits of innumerable degrees. It establishes that flame, justly and freely posited, becomes fixed and subsists, no less than air and water; nor is it a momentary thing, and only successive in its bulk, by renewal and feeding, as is the case here with us. It maintains that flame has a natural tendency to go and collect itself into globes, after the manner of an earthy nature, but not at all like air and water, which are ga thered together in orbs and the interstices of globes, but never into perfect globes. It avers that the same flamy nature in the proper place, (that is) in the constellated firmament, is dispersed in infinite round atoms, but yet. in such s rt thai

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