thermometer is a conspicuous instance of the expansive motion, which (as has been observed) constitutes the chief part of the form of heat. For although flame clearly exhibit expansion, yet, from its being extinguished every moment, it does not exhibit the progress of expansion. Boiling water again, from its rapid conversion into vapour, does not so well exhibit the expansion of water in its own shape: whilst red hot iron and the like are so far from showing this progress, that, on the contrary, the expansion itself is scarcely evident to the senses, on account of its spirit being repressed and weakened by the compact and coarse particles which subdue and restrain it. But the thermometer strikingly exhibits the expansion of the air as being evident and progressive, durable and not transitory.

Take another example. Let the required nature be weight. Quicksilver is a conspicuous instance of weight: for it is far heavier than any other substance, except gold, which is not much heavier; and it is a better instance than gold for the purpose of indicating the form of weight. For gold is solid and consistent, which qualities must be referred to density, but quicksilver is liquid, and teeming with spirit, yet much heavier than the diamond and other substances considered to be most solid. Whence it is shown that the form of gravity or weight predominates only in the quantity of matter, and not in the close fitting of it.

25. In the fourth rank of prerogative instances we will class Clandestine instances; which we are also wont to call twilight instances. They are as it were opposed to the conspicuous instances: for they show the required nature in its lowest state of efficacy, and as it were its cradle and first rudiments, making an effort, and a sort of first attempt, but concealed and subdued by a contrary nature. Such instances are, however, of great importance in discovering forms, for as the conspicuous tend easily to differences, so do the clandestine best lead to genera; that is to those common natures of which the required natures are only the limits.

As an example: let consistency, or that which confines itself, be the required nature, the opposite of which is a liquid or flowing state. The clandestine instances are such as exhibit some weak and low degree of consistency in fluids, as a water bubble, which is a sort of consistent and bounded pellicle formed out of the substance of the water. So eaves' droppings, if there be enough water to follow them, draw themselves out into a thin thread, not to break

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the continuity of the water, but if there be not enough to follow, the water forms itself into a round drop, which is the best form to prevent a breach of continuity: and at the moment the thread ceases, and the water begins to fall in drops, the thread of water recoils upwards to avoid such a breach. Nay in metals, which when melted, are liquid but more tenacious, the melted drops often recoil and are suspended. There is something similar in the instance of the child's looking-glass, which little boys will sometimes form of spittle between rushes, and where the same pellicle of water is observable: and still more in that other amusement of children, when they take some water rendered a little more tenacious by soap, and inflate it with a pipe forming the water into a sort of castle of bubbles, which assumes such consistency by the interposition of the air as to admit of being thrown some little distance without bursting. The best example is that of froth and snow, which assume such consistency as almost to admit of being cut, although composed of air and water, both liquids. All these circumstances clearly show that the terms liquid and consistent are merely vulgar notions adapted to the sense, and that in reality all bodies have a tendency to avoid a breach of continuity, faint and weak in bodies composed of homogeneous parts (as is the case with liquids), but more vivid and powerful in those composed of heterogeneous parts: because the approach of heterogeneous matter binds bodies together, whilst the insinuation of homogeneous matter loosens and relaxes them.

But

Again to take another example; let the required nature be attraction or the cohesion of bodies. The most remarkable conspicuous instance with regard to its form is the magnet. The contrary nature to attraction is non-attraction, though in a similar substance. Thus iron does not attract iron, lead lead, wood wood, nor water water. the clandestine instance is that of the magnet armed with iron, or rather that of iron in the magnet so armed. For its nature is such that the magnet when armed does not attract iron more powerfully at any given distance, than when unarmed; but if the iron be brought in contact with the armed magnet, the latter will sustain a much greater weight than the simple magnet, from the resemblance of substance in the two portions of iron, a quality altogether clandestine and hidden in the iron, until the magnet was introduced. It is manifest, therefore, that the form of cohesion is something which is vivid and robust in the magnet,

and hidden and weak in the iron. It is to be observed also that small wooden arrows without an iron point, when discharged from large mortars, penetrate further into wooden substances (such as the ribs of ships or the like), than the same arrows pointed with iron;* owing to the similarity of substance, though this quality was previously latent in the wood. Again, although in the mass, air does not appear to attract air, nor water water; yet when one bubble is brought near another, they are both more readily dissolved from the tendency to contact of the water with the water, and the air with the air. These clandestine instances (which are, as has been observed, of the most important service) are principally to be observed in small portions of bodies, for the larger masses observe more universal and general forms, as will be mentioned in its proper place.

26. In the fifth rank of prerogative instances we will class Constitutive instances, which we are wont also to call collective instances. They constitute a species or lesser form, as it were, of the required nature. For since the real forms (which are always convertible with the given nature) lie at some depth, and are not easily discovered, the necessity of the case and the infirmity of the human understanding require that the particular forms, which collect certain groups of instances (but by no means all) into some common notion, should not be neglected, but most diligently observed. For whatever unites nature, even imperfectly, opens the way to the discovery of the form. The instances, therefore, which are serviceable in this respect are of no mean power, but endowed with some degree of prerogative.

Here, nevertheless, great care must be taken, that after the discovery of several of these particular forms, and the establishing of certain partitions or divisions of the required nature derived from them, the human understanding do not at once rest satisfied, without preparing for the investigation of the great or leading form, and, taking it for ganted that nature is compound and divided from its very root,

Query?

+ The real cause of this phenomenon is the attraction of the surface water in the vessel by the sides of the bubbles. When the bubbles approach, the sides nearest each other both tend to raise the small space of water between them, and consequently less water is raised by each of these nearer sides, than by the exterior part of the bubble, and the greater weight of the water raised on the exterior parts pushes the bubbles together. In the same manner a bubble near the side of a vessel is pushed towards it; the vessel and bubble both drawing the water that is between them. The latter phenomenon cannot be explained on Bacon's hypothesis.

despise and reject any farther union as a point of superfluous refinement, and tending to mere abstraction.

For instance, let the required nature be memory or that which excites and assists memory. The constitutive instances are order or distribution, which manifestly assists memory; topics or commonplaces in artificial memory, which may be either places in their literal sense, as a gate, a corner, a window, and the like, or familiar persons and marks, or any thing else (provided it be arranged in a determinate order), as animals, plants, and words, letters, characters, historical persons, and the like; of which, however, some are more convenient than others. All these common-places materially assist memory, and raise it far above its natural strength. Verse too is recollected and learnt more easily than prose. From this group of three instances, order, the common-places of artificial memory, and verses, is constituted one species of aid for the memory, which may be well termed a separation from infinity. For when a man strives to recollect or recall any thing to memory, without a preconceived notion or perception of the object of his search, he inquires about, and labours, and turns from point to point, as if involved in infinity. But if he have any preconceived notion, this infinity is separated off, and the range of his memory is brought within closer limits. In the three instances given above, the preconceived notion is clear and determined. In the first it must be something that agrees with order; in the second an image which has some relation or agreement with the fixed common-places; in the third words which fall into a verse: and thus infinity is divided off. Other instances will offer another species, namely, that whatever brings the intellect into contact with something that strikes the sense (the principal point of artificial memory), assists the memory. Others again offer another species, namely, whatever excites an impression by any powerful passion, as fear, wonder, shame, delight, assists the memory. Other instances will afford another species: thus those impressions remain most fixed in the memory which are taken from the mind when clear and least occupied by preceding or succeeding notions, such as the things we learn in childhood, or imagine before sleep, and the first time of any circumstance happening. Other instances afford the following species: namely, that a multitude of circumstances or handles, assist the memory, such as writing in paragraphs, reading aloud or recitation. Lastly, other instances afford still another species: thus the things

we anticipate, and which rouse our attention, are more easily remembered than transient events; as if you read any work twenty times over, you will not learn it by heart so readily, as if you were to read it but ten times, trying each time to repeat it, and when your memory fails you looking into the book. There are, therefore, six lesser forms, as it were, of things which assist the memory: namely, 1. The separation of infinity. 2. The connexion of the mind with the senses. 3. The impression in strong passion. 4. The impression on the mind when pure. The multitude of handles. 6. Anticipation.

Again, for example's sake, let the required nature be taste or the power of tasting. The following instances are constitutive: 1. Those who do not smell, but are deprived by nature of that sense, do not perceive or distinguish rancid or putrid food by their taste; nor garlic from roses, and the like. 2. Again, those whose nostrils are obstructed by accident (such as a cold) do not distinguish any putrid or rancid matter from any thing sprinkled with rose water. 3. If those who suffer from a cold blow their noses violently at the very moment in which they have any thing fœtid or perfumed in their mouth, or on their palate, they instantly have a clear perception of the fœtor or perfume. These instances afford and constitute this species or division of taste: namely, that it is in part nothing else than an internal smelling passing and descending through the upper passages of the nostrils to the mouth and palate. But, on the other hand, those whose power of smelling is deficient, or obstructed, perceive what is salt, sweet, pungent, acid, rough, and bitter, and the like, as well as any one else: so that the taste is clearly something compounded of the internal smelling, and an exquisite species of touch which we will not here discuss.

Again, as another example, let the required nature be the communication of quality, without intermixture of substance. The instance of light will afford or constitute one species of communication, heat and the magnet another. For the communication of light is momentary and immediately arrested upon the removal of the original light. But heat and the magnetic force when once transmitted to, or excited in another body, remain fixed for a considerable time after the removal of the source.

In fine the prerogative of constitutive instances is considerable, for they materially assist the definitions (especially in detail) and the divisions or partitions of natures, con