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the steel a power of adhering to steel, as a homo. geneous substance, the power of the magnet breaking through the sluggishness of the steel. With regard to the assistance of motion, it is seen in wooden arrows or points, which penetrate more deeply into wood than if they were tipped with iron, from the similarity of the substance, the swiftness of the motion breaking through the sluggishness of the wood; of which two last experiments we have spoken above, in the aphorism on clandestine instances.*

have obscured all others, yet they know but little | magnet when armed with steel, for it excites in about it, and commit many errors in its estimate. Let the eighth be that which we term the motion of lesser congregation, by which the homogeneous parts in any body separate themselves from the heterogenous and unite together, and whole bodies of a similar substance coalesce and tend towards each other, and are sometimes congregated, attracted, and meet, from some distance; thus, in milk the cream rises after a certain time, and in wine the dregs and tartar sink; which effects are not to be attributed to gravity and levity only, so as to account for the rising of some parts and the sinking of others, but much more to the desire of the homogeneous bodies to meet and unite. This motion differs from that of need in two points: 1st. Because the latter is the stimulus of a malignant and contrary nature; whilst in this of which we treat, (if there be no impediment or restraint,) the parts are united by their affinity, although there be no foreign nature to create a struggle; 2dly. Because the union is closer and more select. For, in the other motion, bodies which have no great affinity unite, if they can but avoid the hostile body, whilst in this, substances which are connected by a decided kindred resemblance, come together and are moulded into one. It is a motion existing in all compound bodies, and would be readily seen in each, if it were not confined and checked by the other affections and necessities of bodies which disturb the union.

The confinement of the motion of lesser congregation, which arise from the power of the predominant body, is shown in the decomposition of blood and urine by cold. For, as long as these substances are filled with the active spirit, which regulates and restrains each of their component parts, as the predominant ruler of the whole, the several different parts do not collect themselves separately on account of the check; but as soon as that spirit has evaporated, or has been choked by the cold, then the decomposed parts unite, according to their natural desire. Hence, it happens, that all bodies which contain a sharp spirit (as salts, and the like) last, without decomposition, owing to the permanent and durable power of the predominating and imperious spirit.

The confinement of the motion of lesser congregation, which arises from external motion, is very evident in that agitation of bodies, which This motion is usually confined in the three preserves them from putrefaction. For all putrefollowing manners: by the torpor of the bodies; faction depends on the congregation of the homoby the power of the predominating body; by ex-geneous parts, whence, by degrees, there ensues ternal motion. With regard to the first, it is a corruption of the first form, (as it is called,) and certain that there is more or less sluggishness in the generation of another. For, the decompositangible bodies, and an abhorrence of locomotion: tion of the original form, which is itself the union so that, unless excited, they prefer remaining con- of the homogeneous parts, precedes the putrefactented with their actual state, to placing them- tion, which prepares the way for the generation selves in a better position. There are three of another. This decomposition, if not intermeans of breaking through this sluggishness: rupted, is simple; but if there be various obstaheat; the active power of a similar body; vivid cles, putrefactions ensue, which are the rudiments and powerful motion. With regard to the first, of a new generation. But, if (to come to our heat is, on this account, defined as that which present point) a frequent agitation be excited, by separates heterogeneous, and draws together ho- external motion, the motion towards union (which mogeneous substances; a definition of the peri- is delicate and gentle, and requires to be free from patetics, which is justly ridiculed by Gilbert, all external influence) is disturbed, and ceases; who says it is as if one were to define man to be which we perceive to be the case in innumerable that which sows wheat and plants vineyards; instances. Thus, the daily agitation or flowing being only a definition deduced from effects, and of water prevents putrefaction; winds prevent those but partial. But, it is still more to be the air from being pestilent; corn, turned about blamed, because those effects, such as they are, and shaken in granaries, continues clean; in are not a peculiar property of heat, but a mere short, every thing which is externally agitated, accident, (for cold, as we shall afterwards show, will, with difficulty, rot internally. does the same,) arising from the desire of the homogeneous parts to unite; the heat then assists them in breaking through that sluggishness, which before restrained their desire. With regard to the assistance derived from the power of a similar body, it is most conspicuous in the

We must not omit that union of the parts of bodies which is the principal cause of induration and desiccation. When the spirit or moisture, which has evaporated into spirit, has escaped

* See Aphorism 25.

from a porous body, (such as wood, bone, parch- that which is opposed to the motion of lesser conment, and the like,) the thicker parts are drawn gregation, by which bodies, with a kind of antitogether, and united with a greater effort, and in-pathy, avoid and disperse, and separate themduration or desiccation is the consequence; and this we attribute not so much to the motion of connexion, (in order to prevent a vacuum,) as to this motion of friendship and union.

selves from, or refuse to unite themselves with others of a hostile nature. For, although this may sometimes appear to be an accidental motion, necessarily attendant upon that of the lesser Union from a distance is rare, and yet is to be congregation, because the homogeneous parts met with in more instances than are generally cannot unite, unless the heterogeneous be first observed. We perceive it when one bubble dis- | removed and excluded; yet it is still to be classed solves another, when medicines attract humours separately, and considered as a distinct species, from a similarity of substance, when one string because, in many cases, the desire of avoidance moves another in unison with it on different in-appears to be more marked than that of union. struments, and the like. We are of opinion that It is very conspicuous in the excrements of this motion is very prevalent also in animal spi-animals, nor less, perhaps, in objects odious to rits, but are quite ignorant of the fact. It is, particular senses, especially the smell and taste. however, conspicuous in the magnet, and magnetized iron. Whilst speaking of the motions of the magnet, we must plainly distinguish them, for there are four distinct powers or effects of the magnet which should not be confounded, although the wonder and astonishment of mankind has classed them together. 1. The attraction of the magnet to the magnet, or of iron to the magnet, or of magnetized iron to iron. 2. Its polarity towards the north and south, and its variation. 3. Its penetration through gold, glass, stone, and all other substances. 4. The communication of power from the mineral to iron, and from iron to iron, without any communication of the sub-earth. For heat and cold, when in small quantistances. Here, however, we only speak of the first. There is also a singular motion of attraction between quicksilver and gold, so that the gold attracts quicksilver even when made use of in ointment, and those who work surrounded by the vapours of quicksilver are wont to hold a piece of gold in their mouths, to collect the exhalations, which would otherwise attack the heads and bones, and this piece soon grows white.*plete mass, is prevented from so doing by man's Let this suffice for the motion of lesser congregation.

For a fetid smell is rejected by the nose, so as to produce a sympathetic motion of expulsion at the mouth of the stomach; a bitter and rough taste is rejected by the palate or throat, so as to produce a sympathetic concussion and shivering of the head. This motion is visible also in other cases. Thus it is observed in some kinds of antiperistasis, as in the middle region of the air, the cold of which appears to be occasioned by the rejection of cold from the regions of the heavenly bodies; and also in the heat and combustion observed in subterraneous spots, which appear to be owing to the rejection of heat from the centre of the

ties, mutually destroy each other, whilst in larger quantities, like armies equally matched, they remove and eject each other in open conflict. It is said, also, that cinnamon and other perfumes retain their odour longer when placed near privies and foul places, because they will not unite and mix with stinks. It is well known that quicksilver, which would otherwise reunite into a com

spittle, pork, lard, turpentine, and the like, from the little affinity of its parts with those substances, Let the ninth be the magnetic motion, which so that when surrounded by them it draws itself although of the nature of that last mentioned, yet, back, and its avoidance of these intervening obwhen operating at great distances, and on great stacles is greater than its desire of reuniting itself masses, deserves a separate inquiry, especially to its homogeneous parts; which is what they if it neither begin in contact, as most motions term the mortification of quicksilver. Again, the of congregation do, nor end by bringing the sub-difference in weight of oil and water is not the stances into contact, as all do, but only raise only reason for their refusing to mix, but it is also them, and make them swell without any further owing to the little affinity of the two, for spirits effect. For if the moon raise the waters, or of wine, which are lighter than oil, mix very cause moist substances to swell, or if the starry well with water. A very remarkable instance sphere attract the planets towards their apogees, of the motion in question is seen in nitre, and or the sun confine the planets Mercury and Venus crude bodies of a like nature, which abhor flame, to within a certain distance of his mass; these as may be observed in gunpowder, quicksilver, motions do not appear capable of being classed and gold. The avoidance of one pole of the under either of those of congregation, but to be, magnet by iron is not, (as Gilbert has well obas it were, intermediately and imperfectly congre- served,) strictly speaking, an avoidance, but a gative, and thus to form a distinct species. conformity, or attraction to a more convenient

Let the tenth motion be that of avoidance, or situation.


+ Observe this approximation to Newton's theory!

Let the eleventh motion be that of assimilation, or self-multiplication, or simple generation, by

motions, bodies appear to aim at the mere preservation of their nature, whilst in this they attempt its propagation.

body. The latter proceeds by art, insinuation, and stealth, inviting and disposing the excited towards the nature of the exciting body. The former both multiplies and transforms bodies and substances; thus a greater quantity of flame, air, spirit, and flesh is formed; but in the latter, the powers only are multiplied and changed, and heat, the magnetic power, and putrefaction, in the above instances, are increased. Heat does not diffuse itself, when heating other bodies, by any communication of the original heat, but only by exciting the parts of the heated body to that motion which is the form of heat, and of which we spoke in the first vintage of the nature of heat. Heat, therefore, is excited much less rapidly and readily in stone or metal, than in air, on account of the inaptitude and sluggishness of those bodies in acquiring that motion, so that it is probable that there may be some substances, towards the centre of the earth, quite incapable of being heated, on account of their density, which may deprive them of the spirit by which the motion of excitement is usually commenced. Thus, also, the magnet creates in the iron a new disposition of its parts, and a conformable motion. without losing any of its virtue. So the leaven of bread, yeast, rennet, and some poisons, excite and invite successive and continued motion in dough, beer, cheese, or the human body; not so much from the power of the exciting, as the predisposition and yielding of the excited body.

which latter term we do not mean the simple generation of integral bodies, such as plants or animals, but of homogeneous bodies. By this motion homogeneous bodies convert those which Let the twelfth motion be that of excitement, are allied to them, or, at least, well disposed and which appears to be a species of the last, and is prepared, into their own substance and nature. sometimes mentioned by us under that name. It Thus flame multiplies itself over vapours and is, like that, a diffusive, communicative, transioily substances, and generates fresh flame; the tive, and multiplying motion; and they agree reair over water and watery substances multiplies markably in their effect, although they differ in itself and generates fresh air; the vegetable and their mode of action, and in their subject-matter. animal spirit, over the thin particles of a watery The former proceeds imperiously, and with auor oleaginous spirit contained in its food, multi-thority; it orders and compels the assimilated to plies itself and generates fresh spirit; the solid be converted and changed into the assimilating parts of plants and animals, as the leaf, flower, the flesh, bone, and the like, each of them assimilate some part of the juices contained in their food, and generate a successive and daily substance. For let none rave with Paracelsus, who (blinded by his distillations) would have it, that nutrition takes place by mere separation, and that the eye, nose, brain, and liver, lie concealed in bread and meat, the root, leaf, and flower, in the juice of the earth; asserting that just as the artist brings out a leaf, flower, eye, nose, hand, foot, and the like, from a rude mass of stone or wood, by the separation and rejection of what is superfluous; so the great artist within us brings out our several limbs and parts by separation and rejection. But to leave such trifling, it is most certain that all the parts of vegetables and animals, as well the homogeneous as organic, first of all attract those juices contained in their food, which are nearly common, or at least not very different, and then assimilate and convert them into their own nature. Nor does this assimilation, or simple generation, take place in animated bodies only, but the inanimate also participate in the same property, (as we have observed of flame and air,) and that languid spirit, which is contained in every tangible animated substance, is perpetually working upon the coarser parts, and converting them into spirit, which afterwards is exhaled, whence ensues a diminution of weight, and a desiccation of which we have spoken elsewhere.* Nor should we, in speaking of assimilation, neglect to mention the accres tion which is usually distinguished from aliment, and which is observed when mud grows into a mass between stones, and is converted into a stony substance, and the scaly substance round the teeth is converted into one no less hard than the teeth themselves; for we are of opinion that there exists in all bodies a desire of assimilation, as well as of uniting with homogeneous masses. Each of these powers, however, is confined, although in different manners, and should be diligently investigated, because they are connected with the revival of old age. Lastly, it is worthy of observation, that in the nine preceding

* See the citing instances, Aphorism 40.

Let the thirteenth motion be that of impression, which is also a species of motion of assimilation, and the most subtile of diffusive motions. We have thought it right, however, to consider it as a distinct species, on account of its remarkable difference from the two last. For the simple motion of assimilation transforms the bodies themselves, so that if you remove the first agent, you diminish not the effect of those which succeed: thus, neither the first lighting of flame, nor the first conversion into air, are of any importance to the flame or air next generated. So, also, the motion of excitement still continues for a considerable time after the removal of the first agent. as in a heated body on the removal of the original heat, in the excited iron on the removal of the magnet, and in the dough on the removal of the

leaven. But the motion of impression, although diffusive and transitive, appears, nevertheless, to depend on the first agent, so that, upon the removal of the latter, the former immediately fails and perishes; for which reason also it takes effect in a moment, or at least a very short space of time. We are wont to call the two former motions the motions of the generation of Jupiter, because when born they continue to exist; and the latter, the motion of the generation of Saturn, because it is immediately devoured and absorbed. It may be seen in three instances; 1. In the rays of light; 2. In the percussions of sounds; 3. In magnetic attractions as regards communication. For, on the removal of light, colours and all its other images disappear, as, on the cessation of the first percussion and the vibration of the body, sound soon fails; and although sounds are agitated by the wind, like waves, yet it is to be observed, that the same sound does not last during the whole time of the reverberation. Thus, when a bell is struck, the sound appears to be continued for a considerable time, and one might easily be led into the mistake of supposing it to float and remain in the air during the whole time, which is most erroneous. For the reverberation is not one identical sound, but the repetition of sounds; which is made manifest by stopping and confining the sonorous body; thus, if a bell be stopped and held tightly, so as to be immovable, the sound fails, and there is no further reverberation; and if a musical string be touched after the first vibration, either with the finger, (as in the harp,) or a quill, (as in the harpsichord,) the sound immediately ceases. If the magnet be removed, the iron falls. The moon, however, cannot be removed from the sea, nor the earth from a heavy falling body, and we can, therefore, make no experiment upon thein, but the case is the same.

may be put, for it must also revolve round certain poles, and why should they be placed where they are, rather than elsewhere? The polarity and variation of the needle come under our present head. There is also observed in both natural and artificial bodies, especially solids rather than fluids, a particular collocation and position of parts, resembling hairs or fibres, which should be diligently investigated, since, without a discovery of them, bodies cannot be conveniently controlled or wrought upon. The eddies observable in liquids by which, when compressed, they successively raise different parts of their mass before they can escape, so as to equalize the pressure, is more correctly assigned to the motion of liberty.

Let the fifteenth motion be that of transmission, or of passage, by which the powers of bodies are more or less impeded or advanced by the medium, according to the nature of the bodies and their effective powers, and also according to that of the medium. For one medium is adapted to light, another to sound, another to heat and cold, another to magnetic action, and so on with regard to the other actions.

Let the sixteenth be that which we term the royal or political motion, by which the predominant and governing parts of any body check, subdue, reduce, and regulate the others, and force them to unite, separate, stand still, move, or assume a certain position, not from any inclination of their own, but according to a certain order, and as best suits the convenience of the governing part, so that there is a sort of dominion and civil government exercised by the ruling part over its subjects. This motion is very conspicuous in the spirits of animals, where, as long as it is in force, it tempers all the motion of the other parts. It is found in a less degree in other bodies, as we have observed in blood and urine, which are not Let the fourteenth motion be that of configura- decomposed until the spirit, which mixed and tion or position, by which bodies appear to desire retained their parts, has been emitted or extina peculiar situation, collocation, and configuration guished. Nor is this motion peculiar to spirits with others, rather than union or separation. This only, although in most bodies the spirit predomiis a very abstruse motion, and has not been well nates, owing to its rapid motion and penetration; investigated; and, in some instances, appears to for the grosser parts predominate in denser booccur almost without any cause, although we be dies, which are not filled with a quick and active mistaken in supposing this to be really the case. spirit, (such as exists in quicksilver or vitriol,) For if it be asked, why the heavens revolve from so that unless this check or yoke be thrown off east to west, rather than from west to east, or why by some contrivance, there is no hope of any they turn on poles situated near the Bears, rather transformation of such bodies. And let not any than round Orion or any other part of the heaven, one suppose that we have forgotten our subject, such a question appears to be unreasonable, since because we speak of predominance in this clas these phenomena should be received as determi-sification of motions, which is made entirely nate, and the objects of our experience. There with the view of assisting the investigation of are, indeed, some ultimate and self-existing phenomena in nature, but those which we have just mentioned are not to be referred to that class: for we attribute them to a certain harmony and consent of the universe, which has not yet been properly observed. But if the motion of the earth from west to east be allowed, the same question

wrestling instances, or instances of predomi nance. For we do not now treat of the general predominance of motions or powers, but of that of parts in whole bodies, which constitutes the particular species here considered.

Let the seventeenth motion be the spontaneous motion of revolution, by which bodies having a

tendency to move, and placed in a favourable situation, enjoy their peculiar nature, pursuing themselves and nothing else, and seeking as it were to embrace themselves. For bodies seem either to move without any limit, or to tend towards a limit, arrived at which, they either revolve according to their peculiar nature, or rest. Those which are favourably situated, and have a tendency to motion, move in a circle with an eternal and unlimited motion; those which are favourably situated and abhor motion, rest. Those which are not favourably situated move in a straight ine, (as their shortest path,) in order to unite with others of a congenial nature. This motion of revolution admits of nine differences; 1. With regard to the centre about which the bodies move; 2. The poles round which they move; 3. The circumference or orbit relatively to its distance from the centre; 4. The velocity or greater or less speed with which they revolve; 5. The direction of the motion, as from east to west, or the reverse; 6. The deviation from a perfect circle, by spiral lines at a greater or less distance from the centre; 7. The deviation from the circle by spiral lines at a greater or less distance from the poles; 8. The greater or less distance of these spirals from each other; 9. And, lastly, the variation of the poles, if they be movable; which, however, only affects revolution when circular. The motion in question is, according to common and long received opinion, considered to be that of the heavenly bodies. There exists, however, with regard to this, a considerable dispute between some of the ancients as well as moderns, who have attributed a motion of revolution to the earth. A much more reasonable controversy, perhaps, exists, (if it be not a matter beyond dispute,) whether the motion in question (on the hypothesis of the earth's being fixed) is confined to the heavens, or rather descends and is communicated to the air and water. The rotation of missiles, as in darts, inusket balls, and the like, we refer entirely to the motion of liberty.

Let the eighteenth motion be that of trepidation, to which (in the sense assigned to it by astronomers) we do not give much credit; but in our serious and general search after the tendencies of natural bodies, this motion occurs and appears worthy of forming a distinct species. It is the motion of an (as it were) eternal captivity; when bodies, for instance, being placed not altogether according to their nature, and yet not exactly ill, constantly tremble, and are restless, not contented with their position, and yet not daring to advance. Such is the motion of the heart and the pulse of animals, and it must necessarily occur in all bodies which are situated in a mean state, between conveniences and inconveniences; so that being removed from their proper position, they strive to escape, are repulsed, and again continue to make the attempt.


Let the nineteenth and last motion be one which can scarcely be termed a motion, and yet is one; and which we may call the motion of repose, or of abhorrence of motion. It is by this motion that the earth stands by its own weight, whilst its extremes move towards the middle, not to an imaginary centre, but in order to unite. It is owing to the same tendency, that all bodies of considerable density abhor motion, and their only tendency is not to move, which nature they preserve, although excited and urged in a variety of ways to motion. But if they be compelled to move, yet do they always appear anxious to recover their former state, and to cease from motion, in which respect they certainly appear active, and attempt it with sufficient swiftness and rapidity, as if fatigued and impatient of delay. We can only have a partial representation of this tendency, because with us every tangible substance is not only not condensed to the utmost, but even some spirit is added, owing to the action and concocting influence of the heavenly bodies.

We have now, therefore, exhibited the species or simple elements of the motions, tendencies, and active powers, which are most universal in nature; and no small portion of natural science has been thus sketched out. We do not, however, deny that other instances can, perhaps, be added, and our divisions changed according to some more natural order of things, and also reduced to a less number; in which respect we do not allude to any abstract classification, as if one were to say, that "bodies desire the preservation, exaltation, propagation, or fruition of their nature;" or, that "motion tends to the preservation and benefit either of the universe, (as in the case of those of resistance and connection,) or of exten sive wholes, (as in the case of those of the greater congregation, revolution, and abhorrence of motion,) or in particular forms, as in the case of the others. For, although such remarks be just, yet, unless they terminate in matter and construction, according to true definitions, they are speculative and of little use. In the mean time, our classification will suffice, and be of much use in the consideration of the predominance of powers, and examining the wrestling instances which constitute our present subject.

For, of the motions here laid down, some are quite invincible, some more powerful than others, which they confine, check, and modify; others extend to a greater distance, others are more immediate and swift, others strengthen, increase, and accelerate the rest.

The motion of resistance is most adamantine and invincible. We are yet in doubt whether such be the nature of that of connection; for we cannot with certainty determine whether there be a vacuum, either extensive or intermixed with matter. Of one thing, however, we are satisfied, that the reason assigned by Leucippus and De

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