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water appears hot if the hand be told, and cold if as those of a lion, an eagle, a rose, gold, or the the hand be hot.

Aph. 14.

Any one may readily see how poor we are in history, since in the above tables, besides occasionally inserting traditions and report instead of approved history and authentic instances, (always, however, adding some note if their credit or authority be doubtful,) we are often forced to subjoin, "Let the experiment be tried."-"Let further inquiry be made."

like. The moment for discussing these will ar rive, when we come to treat of the latent process, and latent conformation and the discovery of them as they exist in what are called substances, or concrete natures.

Nor, again, would we be thought to mean (even when treating of simple natures) any abstract forms or ideas, either undefined or badly defined in matter. For when we speak of forms, we mean nothing else than those laws and regulations of simple action, which arrange and constitute any simple nature, such as heat, light, weight, in every species of matter, and in a susceptible subject. The form of heat, or form of light, therefore, means no more than the law of heat, or the law of light. Nor do we ever ab

operative branch of philosophy. When, therefore, we say, (for instance,) in our investigation of the form of heat, reject rarity, or rarity is not of the form of heat, it is the same as if we were to say, "Man can superinduce heat on a dense body," or the reverse, "Man can abstract or ward off heat from a rare body."

15. We are wont to term the office and use of these three tables, the presenting a review of instances to the understanding; and when this has been done, induction itself is to be brought into action. For on an individual review of all the instances, a nature is to be found, such as always to be pre-stract or withdraw ourselves from things, and the sent and absent with the given nature, to increase and decrease with it, and as we have said, to form a more common limit of the nature. If the mind attempt this affirmatively from the first, (which it always will when left to itself,) there will spring up phantoms, mere theories and ill-defined notions, with axioms requiring daily correction. These will, doubtless, be better or worse, accord- But if our forms appear to any one to be someing to the power and strength of the understand- what abstracted, from their mingling and uniting ing which creates them. But it is only for God, heterogeneous objects, (the heat, for instance, of (the bestower and creator of forms,) and perhaps the heavenly bodies, appears to be very different for angels and intelligences, at once to recognise from that of fire; the fixed red of the rose and the forms affirmatively, at the first glance of contem-like, from that which is apparent in the rainbow, plation man at least is unable to do so, and is or the radiation of opal or the diamond;* death only allowed to proceed first by negatives, and by drowning, from that by burning, the sword, then to conclude with affirmatives, after every apoplexy, or consumption; and yet they all agree species of exclusion. in the common natures of heat, redness, and

16. We must therefore effect a complete solu-death,) let him be assured that his understanding tion and separation of nature; not by fire, but by is enthralled by habit, by general appearances and the mind, that divine fire. The first work of hypotheses. For it is most certain that, however legitimate induction, in the discovery of forms, heterogeneous and distinct, they agree in the form is rejection, or the exclusive instances of individual natures, which are not found in some one instance, where the given nature is present, or are found in any one instance where it is absent, or are found to increase in any one instance where the given nature decreases, or the reverse. After an exclusion correctly effected, an affirmative form will remain as the residuum, solid, true, and well defined, whilst all volatile opinions go off in smoke. This is readily said, but we must arrive at it by a circuitous route. We shall, perhaps, however, omit nothing that can facilitate our pro-clusion or rejection of natures, found by the tables gress.

or law which regulates heat, redness, or death; and that human power cannot be emancipated and freed from the common course of nature, and expanded and exalted to new efficients and new modes of operation, except by the revelation and invention of forms of this nature. But after this union of nature, which is the principal point, we will afterwards, in its proper place, treat of the divisions and ramifications of nature, whether ordinary or internal, or more real.

18. We must now offer an example of the ex

of review, not to be of the form of heat; first, premising, that not only each table is sufficient for the rejection of any nature, but even each sin gle instance contained in them. For it is clear from what has been said, that every contradictory

17. The first and almost perpetual precaution and warning which we consider necessary is this: that none should suppose from the great part assigned by us to forms, that we mean such forms as the meditations and thoughts of men have hitherto been accustomed to. In the first place, we do not at present mean the concrete forms, which (as we have observed) are in the common course of things compounded of simple natures, enumerated above.

* This general law or form, has been well illustrated by Newton's discovery of the decomposition of colours. i. e. the common link or form which connects the various kinds of natures, such as the different hot or red natures See Aphorism 3 Part 2.

instance destroys an hypothesis as to the form. Still, however, for the sake of clearness, and in order to show more plainly the use of the tables, we redouble or repeat the exclusive.

reject principal nature, by which we mean that which exists positively, and is not caused by a preceding nature.

There are other natures to be rejected; but we

An Example of the exclusive Table, or of the Rejec- are merely offering examples, and not perfect Rejectables. tion of Natures from the Form of Heat.

1. On account of the sun's rays reject elementary (or terrestrial) nature.

2. On account of common fire, and particularly subterranean fires, (which are the most remote and secluded from the rays of the heavenly bodies.) reject celestial nature.

3. On account of the heat acquired by every description of substances, (as minerals, vegetables, the external parts of animals, water, oil, air, &c.) by mere approximation to the fire or any warm body, reject all variety and delicate texture of bodies.

4. On account of iron and ignited metals, which warm other bodies, and yet neither lose their weight nor substance, reject the imparting or mixing of the substance of the heating body. 5. On account of boiling water and air, and also those metals and other solid bodies which are heated, but not to ignition, or red heat, reject flame or light.

6. On account of the rays of the moon and other heavenly bodies, (except the sun,) again reject flame or light.

7. On account of the comparison between redhot iron and the flame of spirits of wine, (for the iron is more hot and less bright, whilst the flame of spirits of wine is more bright and less hot,) again reject flame and light.

8. On account of gold and other ignited metals, which are of the greatest specific density, reject rarity.

9. On account of air, which is generally found to be cold and yet continues rare, reject rarity.

10. On account of ignited iron,* which does not swell in bulk, but retains the same apparent dimension, reject the absolute expansive motion of the whole.

None of the above natures are of the form of heat; and man is freed from them all in his operation upon heat.

Aph. 19.

In the exclusive table are laid the foundations of true induction, which is not, however, completed until the affirmative be attained. Nor is the exclusive table perfect, nor can it be so at first. For it is clearly a rejection of simple natures; but if we have not as yet good and just notions of simple natures, how can the exclusive table be made correct? Some of the above, as the notion of elementary and celestial nature and rarity, are vague and ill-defined. We, therefore, who are neither ignorant nor forgetful of the great work which we attempt, in rendering the human understanding adequate to things and nature, by no means rest satisfied with what we have hitherto enforced; but push the matter farther, and contrive and prepare more powerful aid for the use of the understanding, which we will next subjoin. And, indeed, in the interpretation of nature, the mind is to be so prepared and formed, as to rest itself on proper degrees of certainty, and yet to remember, (especially at first,) that what is present, depends much upon what remains behind.

20. Since, however, truth emerges more readily from error than confusion, we consider it useful to leave the understanding at liberty to exert itself, and attempt the interpretation of nature in the affirmative, after having constructed and weighed the three tables of preparation, such as we have laid them down, both from the instances there collected, and others occurring elsewhere. Which attempt we are wont to call the liberty of the understanding, or the commencement of interpre

The first Vintage of the Form of Heat.

11. On account of the expansion of the air in | tation, or the first vintage. thermometers, and the like, which is absolutely moved and expanded to the eye, and yet acquires no manifest increase of heat, again reject absolute or expansive motion of the whole.

12. On account of the ready application of heat to all substances, without any destruction or remarkable alteration of them, reject destructive nature or the violent communication of any new

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It must be observed that the form of any thing is inherent (as appears clearly from our premises) in each individual instance in which the thing itself is inherent, or it would not be a form. No contradictory instance, therefore, can be alleged. The form, however, is found to be much more conspicuous and evident in some instances than in others; in those, for example, where its nature is less restrained and embarrassed, and reduced to rule by other natures. Such instances we ar wont to term coruscations, or conspicuous in stances. We must proceed then to the first vin tage of the form of heat.

From the instances taken collectively, as wel

s singly, the nature whose limit is heat appears to be motion. This is chiefly exhibited in flame, which is in constant motion, and in warm or boiling liquids, which are likewise in constant motion. It is also shown in the excitement or increase of heat by motion, as by bellows and draughts: for which see Inst. 29, Tab. 3, and by other species of motion, as in Inst. 28 and 31, Tab. 3. It is also shown by the extinction of fire and heat upon any strong pressure, which restrains and puts a stop to motion; for which see Inst. 30 and 32, Tab. 3. It is further shown by this circumstance, namely, that every substance is destroyed, or at least materially changed, by strong and powerful fire and heat: whence it is clear that tumult and confusion are occasioned by heat, together with a violent motion in the internal parts of bodies, and this gradually tends to their dissolution.

What we have said with regard to motion must be thus understood, when taken as the genus of heat it must not be thought that heat generates motion, or motion heat, (though in some respects this be true.) but that the very essence of heat, or the substantial sclf* of heat, is motion and nothing else, limited, however, by certain differences which we will presently add, after giving some cautions for avoiding ambiguity.

Sensible heat is relative, and regards man, not the universe; and is rightly held to be merely the effect of heat on animal spirit. It is even variable in itself, since the same body (in different states of sensations) excites the feeling of heat and of cold; this is shown by Inst. 41, Tab. 3.

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It is also shown in all boiling liquids, which swell, rise, and boil up to the sight, and the process of expansion is urged forward till they are converted into a much more extended and dilated body than the liquid itself, such as steam, smoke, or air.

It is also shown in wood, and combustibles where exudation sometimes takes place, and evaporation always.

It is also shown in the melting of metals, which, being very compact, do not easily swell and dilate, but yet their spirit, when dilated and desirous of further expansion, forces and urges its thicker parts into dissolution, and if the heat be pushed still farther, reduces a considerable part of them into a volatile state.

It is also shown in iron or stones, which, though not melted or dissolved, are, however, softened. The same circumstance takes place in sticks of wood, which become flexible when a little heated in warm ashes.

It is most readily observed in air, which instantly and manifestly expands with a small degree of heat, as in Inst. 38, Tab. 3.

It is also shown in the contrary nature of cold. For cold contracts and narrows every substance; so that, in intense frosts, nails fall out of the wall, and brass cracks, and heated glass, exposed suddenly to the cold, cracks and breaks. So the air by a slight degree of cold contracts itself, as in Inst. 38, Tab. 3. More will be said of this in the inquiry into cold.

Nor is it to be wondered at if cold and heat exhibit many common effects, (for which see Inst. 32, Tab. 2,) since two differences, of which we shall presently speak, belong to each nature: although in the present difference the effects be diametrically opposed to each other. For heat occasions an expansive and dilating motion, but cold a contracting and condensing motion.

Nor should we confound the communication of heat or its transitive nature, by which a body grows warm at the approach of a heated body, with the form of heat. For heat is one thing, and heating another. Heat can be excited by friction without any previous heating body, and, therefore, heating is excluded from the form of II. The second difference is a modification of heat. Even when heat is excited by the approach the preceding, namely, that heat is an expansive of a hot body, this depends not on the form of motion, tending towards the exterior, but at the heat, but on another more profound and common same time bearing the body upwards. For there nature; namely, that of assimilation and multi-is no doubt that there be many compound motions; plication, about which a separate inquiry must be as an arrow or dart, for instance, has both a rotamade. tory and progressive motion. In the same way the motion of heat is both expansive and tending upwards.

The notion of fire is vulgar, and of no assist ance; it is merely compounded of the conjunction of heat and light in any body, as in ordinary flame and red-hot substances.

Laying aside all ambiguity, therefore, we must lastly consider the true differences which limit motion and render it the form of heat.

I. The first difference is, that heat is an expansive motion, by which the body strives to dilate itself, and to occupy a greater space than before. This difference is principally seen in flame, where the smoke or thick vapour is clearly dilated and bursts into flame.

"Quid ipsum," the ro re v cival of Aristotle. Vor. III.-49

This difference is shown by putting the tongs or poker into the fire. If placed perpendicularly with the hand above, they soon burn it, but much less speedily if the hand hold them sloping of from below.

It is also conspicuous in distillations per descen sum, which men are wont to employ with delicate flowers, whose scent easily evaporates. Their industry has devised placing the fire above instead of below, that it may scorch less. For not only flame but all heat has an upward tendency

Let an experiment be made on the contrary 2 K

nature of cold; whether its contraction be down- is very slow, and attacks very minute particles, wards, as the expansion of heat is upwards. no heat is perceived. Take, therefore, two iron rods or two glass tubes, alike in other respects, and warm them a little, and place a sponge, dipped in cold water, or some snow below the one and above the other. We are of opinion that the extremities will grow cold in that rod first where it is placed beneath; as the contrary takes place with regard to heat.

III. The third difference is this. That heat is not a uniform expansive motion of the whole, but of the small particles of the body; and this motion being at the same time restrained, repulsed, and reflected, becomes alternating, perpetually hurrying, striving, struggling, and irritated by the repercussion; which is the source of the violence of flame and heat.

But this difference is chiefly shown in flame and boiling liquids, which always hurry, swell, and subside again in detached parts.

It is also shown in bodies of such hard texture as not to swell or dilate in bulk, such as red-hot iron, in which the heat is most violent.

It is also shown in a comparison of the dissolution of iron and gold. For goid is dissolved without the excitement of any heat, but iron with a vehement excitement of it, although almost in the same time: because, in the former, the penetration of the separating acid is mild, and gently insinuates itself, and the particles of gold yield easily, but the penetration of iron is violent, and attended with some struggle, and its particles are more obstinate.

It is partially shown also in some gangrenes and mortifications of flesh, which do not excite great heat or pain from the gentle nature of the putrefaction.

Let this suffice for a first vintage, or the commencement of the interpretation of the form of heat by the liberty of the understanding.

From this first vintage, the form or true defini. tion of heat (considered relatively to the universe and not to the sense) is briefly thus. "Heat is an expansive motion, restrained and striving to

It is also shown by the fires burning most exert itself in the smaller particles." The expan briskly in the coldest weather.

sion is modified by "its tendency to rise though expanding towards the exterior;" and the effort is modified by its not being sluggish, but active and somewhat violent.

It is also shown by this; that when the air is dilated in the thermometer uniformly and equably, without any impediment or repulsion, the heat is not perceptible. In confined draughts also, al- With regard to the operative definition, the though they break out very violently, no remark-matter is the same. "If you are able to excite a able heat is perceived, because the motion affects the whole, without any alternating motion in the particles. For which reason try whether flame do not burn more at the sides than in its centre.

It is also shown in this, that all burning proceeds by the minute pores of bodies, undermining, penetrating, piercing, and pricking them as if with an infinite number of needlepoints. Hence all strong acids (if adapted to the body on which they act) exhibit the effects of fire from their corroding and pungent nature.

The difference of which we now speak is common also to the nature of cold, in which the contracting motion is restrained by the resistance of expansion, as in heat the expansive motion is restrained by the resistance of contraction.

Whether, therefore, the particles of matter penetrate inwards or outwards, the reasoning is the same, though the power be very different, because we have nothing on earth which is intensely cold.

IV. The fourth difference is a modification of the preceding; namely, that this stimulating or penetrating motion should be rapid and never sluggish, and should take place not in the very minutest particles, but rather in those of some tolerable dimensions.

It is shown by comparing the effects of fire with those of time. Time dries, consumes, undermines, and reduces to ashes as well as fire, and, perhaps. to a much finer degree, but as its motion

dilating or expansive motion in any natural body, and so to repress that motion and force it on itself as not to allow the expansion to proceed equally, but only to be partially exerted, and partially repressed, you will, beyond all doubt, produce heat;" without any consideration as to whether the body be of earth (or elementary, as they term it) or imbued with celestial influence, luminous or opaque, rare or dense, locally expanded or contained within the bounds of its first dimensions, verging to dissolution or remaining fixed, animal, vegetable, or mineral, water, or oil, or air, or any other substance whatever susceptible of such mo tion. Sensible heat is the same, but considere relatively to the senses. Let us now proceed to further helps.

21. After our tables of first review, our rejection or exclusive table and the first vintage derived from them, we must advance to the remaining helps of the understanding with regard to the interpretation of nature, and a true and perfect induction; in offering which we will take the examples of cold and heat where tables are necessary, but where fewer instances are required we will go through a variety of others; so as neither to confound investigation nor to narrow our doc. trine.

In the first place, therefore, we will treat of prerogative instances; 2. Of the supports of induction; 3. Of the correction of induction; 4. Of varying the investigation according to the nature

of the subject; 5. Of the prerogative natures with respect to investigation, or of what should be the first or last objects of our research; 6. Of the limits of investigation, or a synopsis of all natures that exist in the universe; 7. Of the application to practical purposes, or of what relates to man; 8. Of the preparations for investigation; 9. And, lastly, of the ascending and descending scale of axioms.

And, although all exclusion advances affirmation, yet this takes place more directly in the same than in different subjects. But, if the form (18 it is quite clear, from what has been advanced) exhibit itself in one subject, it leads to all. The more simple the migration is, the more valuable is the instance. These migrating instances are, moreover, very useful in practice, for, since they manifest the form, coupled with that which 22. Amongst the prerogative instances we will causes or destroys it, they point out the right pracfirst mention solitary instances. Solitary in- tice in some subjects, and thence there is an easy stances are those which exhibit the required transition to those with which they are most nature in subjects that have nothing in common allied. There is, however, a degree of danger with any other subject than the nature in ques- which demands caution, namely, lest they should tion; or which do not exhibit the required nature | refer the form too much to its efficient cause, and in subjects resembling others in every respect except that of the nature in question. For these instances manifestly remove prolixity, and accelerate and confirm exclusion, so that a few of them are of as much avail as many.

For instance: let the inquiry be the nature of colour: Prisms, crystalline gems, which yield colours not only internally but on the wall, dews, &c., are solitary instances. For they have nothing in common with the fixed colours in flowers and coloured gems, metals, woods, &c., except the colour itself. Hence we easily deduce that colour is nothing but a modification of the image of the incident and absorbed light, occasioned in the former case by the different degrees of incidence, in the latter by the various textures and forms of bodies. These are solitary instances as regards similitude.

Again, in the same inquiry, the distinct veins of white and black in marble, and the variegated colours of flowers of the same species, are solitary Instances: for the black and white of marble, and the spots of white and purple in the flowers of the stock, agree in every respect but that of colour. Thence we easily deduce that colour has not much to do with the intrinsic natures of any body, but depends only on the coarser, and, as it were, mechanical arrangement of the parts. These are solitary instances as regards difference. We call them both solitary or wild, to borrow a word from

the astronomers.

23. In the second rank of prerogative instances we will consider Migrating instances. In these, the required nature passes towards generation, having no previous existence, or towards corruption, having first existed. In each of these divisions, therefore, the instances are always twofold, or rather, it is one instance, first in motion or on its passage, and then brought to the opposite conclusion. These instances not only hasten and confirm exclusion, but also reduce affirmation, or the form itself, to a narrow compass. For, the form must be something conferred by this migration, or, on the contrary, removed and destroyed by it.

*This very nearly approaches to Sir I. Newton's discovery

the decomposition of light by the prism.

imbue, or, at least, tinge the understanding with a false notion of the form from the appearance of such cause; which is never more than a vehicle or conveyance of the form. This may easily be remedied by a proper application of exclusion.

Let us then give an example of a migrating instance. Let whiteness be the required nature. An instance which passes towards generation, is glass in its entire, and in its powdered state; or water in its natural state, and when agitated to froth. For glass, when entire, and water, in its natural state, are transparent and not white, but powdered glass and the froth of water are white, and not transparent. We must inquire, therefore, what has happened to the glass or water in the course of this migration. For, it is manifest that the form of whiteness is conveyed and introduced by the bruising of the glass and the agitation of the water. But nothing is found to have been introduced but a diminishing of the parts of the glass and water, and the insertion of air. Yet this is no slight progress towards discovering the form of whiteness, namely, that two bodies, in themselves more or less transparent, (as air and water, or air and glass,) when brought into contact in minute portions, exhibit whiteness, from the unequal refraction of the rays of light.

But here we must also give an example of the danger and caution of which we spoke. For instance; it will readily occur to an understanding perverted by efficients, that air is always necessary for producing the form of whiteness, or that whiteness is only generated by transparent bodies, which suppositions are both false, and proved to be so by many exclusions. Nay, it will rather appear, (without any particular regard to air or the like) that all bodies which are even in such of their parts as affect the sight, exhibit transparency, those which are uneven and of simple texture, whiteness, those which are uneven and of compound but regular texture, all the other colours except black, but those which are uneven and of a compound, irregular, and confused texture, exhibit blackness. An example has been given, therein the required nature of whiteness. An instance fore, of an instance migrating towards generation

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