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below its surface, and affecting the needle in its eye sees better if the object be moved a little polarity, it must act at a great distance.

Again, if there be any magnetic force, which acts by sympathy between the globe of the earth and heavy bodies, or between that of the moon and the waters of the sea, (as seems most probable from the particular floods and ebbs which occur twice in the month,) or between the starry sphere and the planets, by which they are summoned and raised to their apogees; these must all operate at very great distances.* Again, some conflagrations and the kindling of flames take at very considerable distances, with particular substances, as they report of the naphtha of Babylon. Heat, too, insinuates itself at wide distances, as does also cold, so that the masses of ice which are broken off and float upon the Northern Ocean, and are borne through the Atlantic to the coast of Canada, become perceptible by the inhabitants, and strike them with cold from a distance. Perfumes also (though here there appears to be always some corporeal emission) act at remarkable distances; as is experienced by persons sailing by the coast of Florida, or parts of Spain, where there are whole woods of lemons, oranges, and other odoriferous plants, or rosemary and marjorum bushes, and the like. Lastly, the rays of light and the impression of sound act at extensive distances.

Yet all these powers, whether acting at a small or great distance, certainly act within definite distances, which are well ascertained by nature: so that there is a limit depending either on the mass or quantity of the bodies, the vigour or faintness of the powers, or the favourable or impeding nature of the medium, all of which should be taken into account and observed. We must also note the boundaries of violent motions, such as missiles, projectiles, wheels, and the like, since they are also manifestly confined to certain limits.

Some motions and virtues are to be found of a directly contrary nature to these, which act in contact, but not at a distance; namely, such as operate at a distance, and not in contact, and again act with less force at a less distance, and the reverse. Sight, for instance, is not easily effective in contact, but requires a medium and distance; although I remember having heard from a person, deserving of credit, that in being cured of a cataract, (which was done by putting a small silver needle within the first coat of the eye, to remove the thin pellicle of the cataract, and force it into a corner of the eye,) he had distinctly seen the needle moving across the pupil. Still, though this may be true, it is clear that large bodies cannot be seen well or distinctly, unless at the vertex of a cone, where the rays from the object meet at some distance from the eye. In old persons, the

* Observe the approximation to Newton's theory.

farther, and not nearer. Again, it is certain, that in projectiles the impact is not so violent at too short a distance as a little afterwards.* Such are the observations to be made on the measure of motions as regards distance.

There is another measure of motion in space which must not be passed over, not relating to progressive, but spherical motion: that is, the expansion of bodies into a greater, or their contraction into a lesser sphere. For, in our measure of this motion, we must inquire what degree of compression or extension bodies easily and readily admit of, according to their nature, and at what point they begin to resist it, so as, at last, to bear it no farther; as, when an inflated bladder is compressed, it allows a certain compression of the air, but, if this be increased, the air does not suffer it, and the bladder is burst.

We have proved this by a more delicate experiment. We took a metal bell, of a light and thin sort, such as is used for salt-cellars, and immerged it in a basin of water, so as to carry the air contained in its interior down with it to the bottom of the basin. We had first, however, placed a small globe at the bottom of the basin, over which we placed the bell. The result was, that if the globe were small, compared with the interior of the bell, the air would contract itself, and be compressed without being forced out, but, if it were too large for the air readily to yield to it, the latter became impatient of the pressure, raised the bell partly up, and ascended in bubbles.

To prove, also, the extension (as well as the compression) which air admits of, we adopted the following method. We took a glass egg, with a small hole at one end; we drew out the air by violent suction at this hole, and then closed the hole with the finger, immersed the egg in water, and then removed the finger. The air being constrained by the effort made in suction, and dilated beyond its natural state, and, therefore, striving to recover and contract itself, (so that if the egg had not been immersed in water, it would have drawn in the air with a hissing sound,) now drew in a sufficient quantity of water to allow the air to recover its former dimensions.†

It is well ascertained, that rare bodies (such as air) admit of considerable contraction, as has been before observed; but tangible bodies (such as water) admit of it much less readily, and to a less extent. We investigated the latter point by the following experiment.

We had a leaden globe made, capable of containing about two pints, wine measure, and of tolerable thickness, so as to support considerable

* Query.

This passage shows that the pressure of the external at mosphere, which forces the water into the egg, was not, in Bacon's time, understoou.

pressure. We poured water into it through an aperture, which we afterwards closed with melted lead, as soon as the globe was filled with water, so that the whole became perfectly solid. We next flattened the two opposite sides with a heavy hammer, which necessarily caused the water to occupy a less space, since the sphere is the solid of greatest content; and when hammering failed, from the resistance of the water, we inade use of a mill or press, till at last the water, refusing to submit to a greater pressure, exuded, like a fine dew, through the solid lead. We then computed the extent to which the original space had been reduced, and concluded that water admitted such a degree of compression when constrained by great violence.

The more solid, dry, or compact bodies, such as stones, wood, and metals, admit of much less, and, indeed, scarcely any perceptible compression, or expansion, but escape by breaking, slipping forward, or other efforts; as appears in bending wood, or steel for watch-springs, in projectiles, hammering, and many other motions, all of which, together with their degrees, are to be observed and examined in the investigation of nature, either to a certainty, or by estimation, or comparison, as opportunity permits.

46. In the twenty-second rank of prerogative instances, we will place the instances of the course, which we were also wont to call water instances; borrowing our expression from the water hour-glass, employed by the ancients instead of those with sand. They are such as measure nature by the moments of time, as the last instances do by the degrees of space. For all motion or natural action takes place in time, more or less rapidly, but still in determined moments, well ascertained by nature. Even those actions which appear to take effect suddenly, and in the twinkling of an eye, (as we express it,) are found to admit of greater or less rapidity.

In the first place, then, we see that the return of the heavenly bodies to the same place, takes place in regular times, as does the flood and ebb of the sea. The descent of heavy bodies towards the earth, and the ascent of light bodies towards the heavenly sphere, take place in definite times, according to the nature of the body, and of the medium through which it moves. The sailing of ships, the motions of animals, the transmission of projectiles, all take place in times, the sums of which can be computed. With regard to heat, we see that boys in winter bathe their hands in the flame without being burned; and conjurors, by quick and regular movements, overturn vessels filled with wine or water, and replace them without spilling the liquid, with several similar instances. The compression, expansion, and eruption of several bodies, takes place more or less rapidly, according to the nature of the body, and its motion, but still in definite moments.

VOL. III.-52

In the explosion of several cannon at once, (which are sometimes heard at the distance of thirty miles,) the sound of those nearest to the spot, is heard before that of the most distant. Even in sight, (whose action is most rapid,) it is clear that a definite time is necessary for its exertion, which is proved by certain objects being invisible from the velocity of their motion, such as a musket ball. For the flight of a ball is too swift to allow an impression of its figure to be conveyed to the sight.

This last instance, and others of a like nature, have sometimes excited in us a most marvellous doubt, no less than whether the image of the sky and stars is perceived as at the actual moment of its existence, or rather a little after, and whether there is not (with regard to the visible appearance of the heavenly bodies) a true and apparent time, as well as a true and apparent place, which is observed by astronomers in parallaxes.* It appeared so incredible to us, that the images or radiations of heavenly bodies could suddenly be conveyed through such immense spaces to the sight, and it seemed that they ought rather to be transmitted in a definite time. That doubt, however, (as far as regards any great difference between the true and apparent time,) was subsequently completely set at rest, when we consider the infinite loss and diminution of size as regards the real and apparent magnitude of a star, cccasioned by its distance, and at the same time ob. served at how great a distance (at least sixty miles) bodies which are merely white can be suddenly seen by us. For there is no doubt, that the light of heavenly bodies not only far surpass the vivid appearance of white, but even the light of any flame (with which we are acquainted) in the vigour of its radiation. The immense velocity of the bodies themselves, which is perceived in their diurnal motion, and has so astonished thinking men, that they have been more ready to believe in the motion of the earth, renders the motion of radiation from them (marvellous as it is in its rapidity) more worthy of belief. That which has weighed most with us, however, is, that if there were any considerable interval of time between the reality and the appearance, the images would often be interrupted and confused by clouds formed in the mean time, and similar disturbances of the medium. Let this suffice with regard to the simple measures of time.

It is not merely the absolute, but still more the relative measure of motions and actions which must be inquired into, for this latter is of great use and application. We perceive that the flame of fire-arms is seen sooner than the sound is heard, although the ball must have struck the air before the flame, which was behind it, could escape: the reason of which is, that light moves with greater

*This is a singular approximation to Romer's discovery of time being required for the propagation of light. 2 M

perfume, not inferior to the flower itself, for a whole year. It must be observed, however, that the perfume does not acquire its full strength, till about a month after the infusion. In the distillation of aromatic plants macerated in spirits of wine, it is well known that an aqueous and useless phlegm rises first, then water containing more of the spirit, and lastly, water containing more of the aroma; and many observations of the like kind, well worthy of notice, are to be made in distillations. But let these suffice as examples.

velocity than sound. We perceive, also, that vi- | not altogether remained there for more than one sible images are received by the sight with greater hour and a half, there remains a most pleasing rapidity than they are dismissed, and for this reason, a violin string touched with the finger appears double or triple, because the new image is received before the former one is dismissed. Hence, also, rings when spinning, appear globular, and a lighted torch, borne rapidly along at night, appears to have a tail. Upon the principle of the inequality of motion, also, Galileo attempted an explanation of the flood and ebb of the sea, supposing the earth to move rapidly, and the water slowly, by which means the water, after accumulating, would at intervals fall back, as is shown in a vessel of water made to move rapidly. He has, however, imagined this on data which cannot be granted, (namely, the earth's motion,) and, besides, does not satisfactorily account for the tide taking place every six hours.

An example of our present point, (the relative measure of motion,) and, at the same time, of its remarkable use of which we have spoken, is conspicuous in mines filled with gunpowder, where immense weights of earth, buildings, and the like, are overthrown and prostrated by a small quantity of powder; the reason of which is decidedly this, that the motion of the expansion of the gunpowder is much more rapid than that of gravity, which would resist it, so that the former has terminated before the latter has commenced. Hence, also, in missiles, a strong blow will not carry them so far as a sharp and rapid one. Nor could a small portion of animal spirit in animals, especially in such vast bodies as those of the whale and elephant, have ever bent or directed such a mass of body, were it not owing to the velocity of the former, and the slowness of the latter in resisting its motion.

In short, this point is one of the principal foundations of the magic experiments, (of which we shall presently speak,) where a small mass of matter overcomes and regulates a much larger, if there be but an anticipation of motion, by the velocity of one before the other is prepared to act. Finally, the point of the first and last should be observed in all natural actions. Thus, in an infusion of rhubarb, the purgative property is first extracted, and then the astringent; we have experienced something of the same kind in steeping violets in vinegar, which first extracts the sweet and delicate odour of the flower, and then the more earthy part, which disturbs the perfume; so that if the violets be steeped a whole day, a much fainter perfume is extracted than if they were steeped for a quarter of an hour only, and then taken out; and since the odoriferous spirit in the violet is not abundant, let other and fresh violets be steeped in the vinegar every quarter of an hour, us many as six times, when the infusion becomes so strengthened, that although the violets have

47. In the twenty-third rank of prerogative instances, we will place instances of quantity, which we are also wont to call the doses of nature, (borrowing a word from medicine.) They are such as measure the powers by the quantity of bodies, and point out the effect of the quantity in the degree of power. And, in the first place, some powers only subsist in the universal quantity, or such as bears a relation to the conformation and fabric of the universe. Thus the earth is fixed, its parts fall. The waters in the sea flow and ebb, but not in the rivers, except by the admission of the sea. Then, again, almost all particular powers act according to the greater or less quantity of the body. Large masses of water are not easily rendered foul, small are. New wine and beer become ripe and drinkable in small skins, much more readily than in large casks. If an herb be placed in a considerable quantity of liquid, infusion takes place rather than impregnation, if in less, the reverse. A bath, therefore, and a light sprinkling, produce different effects on the human body. Light dew, again, never falls, but is dissipated and incorporated with the air; thus we see that in breathing on gems the slight quantity of moisture, like a small cloud in the air, is immediately dissolved. Again, a piece of the same magnet does not attract so much iron as the whole magnet did. There are some powers where the smallness of the quantity is of more avail; as in boring, a sharp point pierces more readily than a blunt one; the diamond, when pointed, makes an impression on glass, and the like.

Here, too, we must not rest contented with a vague result, but inquire into the exact proportion of quantity requisite for a particular exertion of power. For one would be apt to suppose that the power bears an exact proportion to the quantity; that if a leaden bullet of one ounce, for instance, would fall in a given time, one of two ounces ought to fall twice as rapidly, which is most erreneous. Nor does the same ratio prevail in every kind of power, their difference being considerable. The measure, therefore, must be determined by experiment, and not by probability or conjecture.

Lastly, we must in all our investigations of nature observe what quantity, or dose, of the body

is requisite for a given effect, and must at the same time be guarded against estimating it at too much or too little.

18. In the twenty-fourth rank of prerogative instances, we will place wrestling instances, which we are also wont to call instances of predominance. They are such as point out the predominance and submission of powers compared with each other, and which of them is the more energetic and superior, or more weak and inferior. For the motions and effects of bodies are compounded, decomposed, and combined, no less than the bodies themselves. We will exhibit, therefore, the principal kinds of motions or active powers, in order that their comparative strength, and thence a demonstration and definition of the instances in question, may be rendered more clear. Let the first motion be that of the resistance of matter, which exists in every particle, and completely prevents its annihilation; so that no conflagration, weight, pressure, violence, or length of time. can reduce even the smallest portion of matter to nothing, or prevent it from being something, and occupying some space, and delivering itself, (whatever straits it be put to,) by changing its form or place, or, if that be impossible, remaining as it is, nor can it ever happen that it should either be nothing or nowhere. This motion is designated by the schools (which generally name and define every thing by its effects and inconveniences, rather than by its inherent cause) by the axiom, "that two bodies cannot exist in the same place," or they call it a motion, " to prevent the penetration of dimensions." It is useless to give examples of this motion, since it exists in every body.

Let the second motion be that which we term the motion of connexion, by which bodies do not allow themselves to be separated at any point from the contact of another body, delighting, as it were, in the mutual connexion and contact. This is called by the schools a motion to prevent a vacuum." It takes place when water is drawn up by suction or a syringe, the flesh by cupping, or when the water remains without escaping from perforated jars, unless the mouth be opened to admit the air, and innumerable instances of a like nature.

Let the third be that which we term the motion of liberty; by which bodies strive to deliver themselves from any unnatural pressure or tension, and to restore themselves to the dimensions suited to their mass; and of which, also, there are innumerable examples. Thus, we have examples of their escaping from pressure, in the water in swimming, in the air in flying, in the water again in rowing, and in the air in the undulations of the winds, and in the springs of watches. An exact instance of the motion of compressed air is seen in children's popguns, which they make by scooping out elder branches,

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or some such matter, and forcing in a piece of some pulpy root, or the like, at each end; then they force the root or other pellet with a ramrod to the opposite end, from which the lower pellet is emitted and projected with a report, and that before it is touched by the other piece of root of pellet, or by the ramrod. We have examples of their escape from tension, in the motion of the air that remains in glass eggs after suction, in strings, leather, and cloth, which recoil after tension, unless it be long continued. The schools define this by the term of motion "from the form of the element;" injudiciously enough, since this motion is to be found not only in air, water, or fire, but in every species of solid, as wood, iron, lead, cloth, parchment, &c., each of which has its own proper size, and is with difficulty stretched to any other. Since, however, this motion of liberty is the most obvious of all, and to be seen in an infinite number of cases, it will be as well to distinguish it correctly and clearly; for some most carelessly confound this with the two others of resistance and connection; namely, the freedom from pressure with the former, and that from tension with the latter; as if bodies when compressed yielded or expanded to prevent a penetration of dimensions, and, when stretched, rebounded and contracted themselves to prevent a vacuum. But if the air, when compressed, could be brought to the density of water, or wood to that of stone, there would be no need of any penetration of dimensions, and yet the compression would be much greater than they actually admit of. So, if water could be expanded till it became as rare as air, or stone as rare as wood, there would be no need of a vacuum, and yet the expansion would be much greater than they actually admit of. We do not, therefore, arrive at a penetration of dimensions or a vacuum, before the extremes of condensation and rarefaction, whilst the motion we speak of stops and exerts itself much within them, and is nothing more than a desire of bodies to preserve their specific density, (or, if it be preferred, their form,) and not to desert them suddenly, but only to change by degrees, and of their own accord. however, much more necessary to intimate to mankind (because many other points depend upon this) that the violent motion which we call mechanical, and Democritus (who, in explaining his primary motions, is to be ranked even below the middling class of philosophers) termed the motion of a blow, is nothing else than this motion of liberty, namely, a tendency to relaxation from compression. For, in all simple impulsion or flight through the air, the body is not displaced or moved in space, until its parts are placed in an unnatural state, and compressed by the impelling force. When that takes place, the different parts urging the other in succession, the whole is moved, and that with a rotatory as well as pro

It is,

gressive motion, in order that the parts may, by this means, also, set themselves at liberty, or more readily submit. Let this suffice for the motion in question.

Let the sixth be that which we term the motion of acquisition, or the motion of need. It is that by which bodies placed amongst others of a heterogenous and, as it were, hostile nature, if they meet with the means or opportunity of avoiding them and uniting themselves with others of a more analagous nature, even when these latter are not closely allied to them, immediately seize and, as it were, select them, and appear to consider it as something acquired, (whence we derive the name,) and to have need of these latter bodies. For instance, gold, or any other metal in leaf, does not like the neighbourhood of air; if, therefore, they meet with any tangible and thick substance, (such as the finger, paper, or the like,) they immediately adhere to it, and are not easily torn from it. Paper, too, and cloth, and the like, do not agree with the air, which is inherent and mixed in their pores. They readily, therefore, imbibe water or other liquids, and get rid of the air. Sugar, or a sponge, dipped in water or wine, and though part of it be out of the water or wine, and at some height above it, will yet gradually absorb them. Hence, an excellent rule is derived for the opening and dissolution of bodies. For, (not to

Let the fourth be that which we term the motion of matter, and which is opposed to the last. For, in the motion of liberty, bodies abhor, reject, and avoid a new size or volume, or any new expansion or contraction, (for these different terms have the same meaning,) and strive, with all their power, to rebound and resume their former density. On the contrary, in the motion of matter they are anxious to acquire a new volume or dimension, and attempt it willingly and rapidly, and occasionally by a most vigorous effort, as in the example of gunpowder. The most powerful, or, at least, most frequent, though not the only instruments of this motion, are heat and cold. For instance, the air, if expanded by tension, (as by suction in the glass egg,) struggles anxiously to restore itself; but if heat be applied, it strives, on the contrary, to dilate itself, and longs for a larger volume, regularly passing and migrating into it, as into a new form, (as it is termed :) nor, after a certain degree of expansion, is it anxious to return, unless it be invited to do so by the ap-mention corrosive and strong waters, which force plication of cold, which is not indeed a return, but a fresh change. So, also, water, when confined by compression, resists, and wishes to become as it was before, namely, more expanded; but if there happen an intense and continued cold, it changes itself readily and of its own accord, into the condensed state of ice; and if the cold be long continued, without any intervening warmth, (as in grottos and deep caves,) it is changed into crystal or similar matter, and never resumes its form.

their way,) if a body can be found which is more adapted, suited, and friendly to a given solid, than that with which it is by some necessity united, the given solid immediately opens and dissolves itself to receive the former, and excludes or removes the latter.* Nor is the effect or power of this motion confined to contact, for the electric energy (of which Gilbert and others after him have told so many fables) is only the energy excited in a body by gentle friction, and which does not endure the air, but prefers some tangible substance, if there be any at hand.

Let the fifth be that which we term the motion of continuity. We do not understand by this, sim- Let the seventh be that which we term the mople and primary continuity with any other body, tion of greater congregation, by which bodies are (for that is the motion of connexion,) but the con-borne towards masses of a similar nature, for intinuity of a particular body in itself. For it is most certain, that all bodies abhor a solution of continuity, some more and some less, but all partially. In hard bodies, (such as steel and glass,) the resistance to an interruption of continuity is most powerful and efficacious, whilst, although in liquids it appears to be faint and languid, yet it is not altogether null, but exists in the lowest degree, and shows itself in many experiments, such as bubbles, the round form of drops, in thin threads which drip from roofs, the cohesion of glutinous substances, and the like. It is most conspicuous, however, if an attempt be made to push this separation to still smaller particles. Thus, in mortars, the pestle produces no effect after a certain degree of contusion, water does not penetrate small fissures, and the air itself, notwithstanding its subtilty, does not penetrate the pores of solid vessels at once, but only by long continued insinuation.

stance, heavy bodies towards the earth, light to the sphere of heaven. The schools termed this natural motion, by a superficial consideration of it, because produced by no external visible agent, which made them consider it innate in the sub stances; or, perhaps, because it does not cease, which is little to be wondered at, since heaven and earth are always present, whilst the causes and sources of many other motions are sometimes absent, and sometimes present. They, therefore, called this perpetual and proper, because it is never interrupted, but instantly takes place when the others are interrupted, and they called the others adscititious. The former, however, is in reality weak and slow, since it yields, and is inferior to the others as long as they act, unless the mass of the body be great; and although this motion have so filled men's minds, as almost to

This is one of the most useful practical methods in cbymistry at the present day

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