3.-GLARING INSTANCES, where the nature sought appears most conspicuous. Thus, if the inquiry be into the expansive motion of heat-the sudden lighting of gas, supposing flame to partake of the nature of heat, exhibits its expansive nature to the sense, but is momentary. Mr. Leslie's experiment on ignited solids shews the expansive nature of heat, but the progress is not immediately visible to the senses. The thermometer shews the expansive nature of heat, both in its progress and duration, and is a glaring instance of the expansive nature of heat.
4.-CLANDESTINE INSTANCES, where the nature appears in its weakest virtue and imperfect state, as froth or bubbles, or the looking glasses made by children, in a loop of a rush, in bubbles of soapy water, &c.
5.-CONSTITUENT INSTANCES, or a separation of the nature sought into the different natures, of which it is composed.
Thus, let the inquiry be "memory," or the means of exeiting and helping the memory.
Things sink deepest in the mind which are made when it is free and disengaged, as in childhood; or when it is in a state of repose, as upon approaching sleep, or just after having awoke; or when alien thoughts are excluded by the influence of strong passions; as impressions which are new, are caused by fear or accompanied by blushing, delight, &c. When parish-boys walk the bounds of their parishes, they are struck to impress the fact on their minds.
Things sink deepest on the mind which are impressed by a multitude of circumstances; as proving the same geometrical proposition by different forms of proof; algebraic, fluxional, geometrical, &c.; or learning the same moral truth in prose and in verse, and in different styles in each.
Difficulty of acquisition seems to be another mode of fixing the impression, according to the proverb,-Light come, light go.
It seems, therefore, that one of the constituent parts of the Art of Memory is the Art of making strong impressions; and that it depends upon the state of the patient, or on freedom of mind; and upon the conduct of the agent in variety and difficulty of acquisition.
The Art of recalling any given Impression forms another constituent part of the Art of Memory.
That which is addressed to the senses strikes more forcibly than that which is addressed to the intellect; the image of a huntsman pursuing a hare, or an apothecary setting his boxes in order, or a man making a speech, or a boy reciting verses by heart, or an actor upon the stage, are more easily remembered than the notions of invention, disposition, elocution,
memory, and action. Images, therefore, and places for artificial memory greatly help it, and raise it far above its natural powers. This doctrine upon which there are many valuable treatises, lately enumerated in a work published upon this branch of the Art of Memory, it seems that Bacon himself practised: for Aubrey, in his description of Lord Bacon's house at Gorhambury, says: "Over this portico is a stately gallery, where glass windows are all painted; and every pane with several figures of beast, bird, or flower: perhaps his lordship might use them as topics for local memory." One part, therefore, of the Art of recalling given Impressions, consists in reducing intellectual to sensible things.
Another branch consists in certain rules for technical memory, to assist the recollection by association, as verse, and the infinity of modes, by which, with some chance of injury to the mind, circumstances are recalled. In such different modes of limiting an indefinite seeking, or of cutting off infinity, of hunting the fallow deer in a park instead of a forest, the constituent parts of the Art of recalling Impressions consists.
The doctrine of memory and its constituent parts may, therefore, be thus exhibited:
1. The Art of making strong
Impressions.
2. The Art of recalling Impressions.
1. Freedom of Mind.
2. Variety and Difficulty of Impressions.
1. Reducing intellectual to sensible things.
2. Technical Rules.
6.-CONFORMABLE INSTANCES, or instances in other natures where there is any conformity with the nature sought, or resemblances in apparent differences; as gums and gems, which are exudations of juices; the one of trees, the other of rocks: hairs of beasts and feathers of birds, &c.
7.-SINGULAR INSTANCES; Instances, which, in regular course, are solitary amidst their own natures, as quicksilver. amongst metals; the carrier pigeon amongst birds; the loadstone amongst stones; the letter S amongst consonants, which may be compounded with three consonants, as strong; &c.
8.-DEVIATING INSTANCES, where nature departs from her ordinary course, or monsters.
9. FRONTIER INSTANCES, those species of bodies which seem composed of two species, or to be rudiments betwixt one species and another, as sensitive plants, flying fish, bats, the ape, &c.
10.-INSTANCES OF POWER, the most noble inventions in every art and science.
If we do but cast our eyes backward to those works already attained, are they not like so many fair provinces conquered and taught a new language? Have there not lately been discovered certain glasses, by means whereof, as by boats or little ships of intelligence, a nearer commerce is opened and carried on with the celestial bodies? Does not the mariner also find, by the help of a small magnet, a safe path in the waters, and wing his way to the harbour as surely as doth heaven's own bird?
11.-ACCOMPANYING AND HOSTILE INSTANCES, in which the sought nature always appears, or never appears. Thus, heat always appears in flame; quiescence of parts never appears with heat.
12. SUBJUNCTIVE INSTANCES Extremes, or maxima and minima, as gold in weight; iron in hardness; the whale in greatness of bulk; the minute worms in the skin in smallness; the hound in scent; &c.
13.-INSTANCES OF ALLIANCE, where natures, supposed to be heterogeneous, are homogeneous, or resemblances in supposed differences. The heat of the sun and culinary heat; the branches and roots of trees; &c.
14.-CRUCIAL INSTANCES, which, when the mind is in equilibrio between two causes, marks the cause of the sought nature. 15.-INSTANCES OF DIVORCE. The separation of such natures as are generally united. Light and heat are generally united; but hot water is without light, and moon-light is often cold.
16.-INSTANCES OF THE PORTAL are such as assist the immediate action of the senses, as microscopes and telescopes, &c. 17.-CITING INSTANCES, which bring down insensible things to such as are sensible, as the discovery of the nature of vital spirit from its effects.
18. JOURNEYING INSTANCES. Such as indicate the mctions of nature gradually continued or connected, as the vegetation of plants, the vivification of eggs, &c.
19.-SUPPLEMENTAL INSTANCES.
Such as afford information where the senses wholly fail; which are either by approximation, as, although the loadstone acts through all mediums, an approximation to the medium where its action would cease, may be made, by discovering a medium in which its power, although not destroyed, is diminished; or by analogy, by discovering the laws of a nature not within the cognizance of the senses, by considering the actions of similar bodies within their cognizance. As the mixture of vital spirits of different,
VOL. IV. PART II.
animals, by considering the mixture of flames from different bodies.
20-LANCING INSTANCES. Such as remind the understanding of the admirable and exquisite subtlety of natures-Which we have already explained.
21. TERMINATING INSTANCES. Those which note the limits in space to the action of bodies. As the distance at which amber or jet, or the magnet, attract bodies, or bubbles attract each other.
22.-HYDROMETICAL INSTANCES, or such as measure nature by moments of time. As the flash of a gun is seen before the sound is heard, or lightning before the thunder.
23.-INSTANCES OF QUANTITY, or such as inquire into the proportion of the quantity of a body with respect to the measure of its virtue, concerning which a very diligent care is to be taken, seeing it is encompassed with many errors. For men are of opinion that if the quantity be augmented and multiplied, the virtue is proportionably augmented and multiplied; and this commonly is with them a postulatum, and a supposed truth, as if the matter were a mathematical certitude; which is utterly untrue. One drachm of sulphur mingled with half a pound of steel, will make it fluid and liquid; will therefore an ounce of sulphur suffice to the dissolving of four pounds of steel? But that follows not; for it is certain that the obstinacy of the matter in the patient is more increased by quantity, than the activity of the virtue in the agent. Men should therefore remember the mockery of Esop's housewife, who conceited that by doubling her measure of barley, her hen would daily lay her two eggs. But the hen grew fat and laid none.
24.-INSTANCES OF RELUCTANCE.-Which shew the predominancy, or subjection of virtues to one another.-This includes the doctrine of all the different motions in nature, gravity, magnetical, &c., and is divided into nineteen different species of motions, of which we select a few specimens. They may be thus exhibited,
1. Tendencies of bodies to preserve their natures.
Excitation,
Assimilation,
The motion of excitation is that which disposes an excited body to assume the nature of the matter exciting. As heat and cold, which may produce their effects, not by a communica
2. Tendencies of bodies to propagate
their natures.
tion of their own substances, but by exciting the parts of the body to that motion of parts in which heat consists. As the magnet which may give iron a new disposition of parts, and a conformable motion without losing any of its virtue.
The motion of impression is that which impresses the body only as long as the exciter is present, as in light, which vanishes the moment the luminous body is removed: or sound, when the bell string is still, &c.
The motion of assimilation is that by which bodies convert others into their own substance and nature, as flame multiplies upon unctuous exhalations and oily bodies: and the spirit of animals feeds and supplies itself from the body, plants, &c.
The Political Motion,-Is that by which parts of the body are restrained from their own immediate appetites or tendencies, to unite in such a state as may preserve the existence of the whole body. Thus the spirit which exists in all living bodies keeps all the parts in due subjection: when it escapes, the body decomposes, or the similar parts unite, as metals rust; fluids turn sour: and in animals, when the spirit which held the parts together escapes, all things are dissolved, and return to their own natures or principles: the oily parts to themselves: the aqueous also to themselves, &c.: upon which necessarily ensues that odour, that unctuosity, that confusion of parts observable in putrefaction: so true is it, that in nature all is beauty: that notwithstanding our partial views and distressing associations, the forms of death, misshapen as we suppose them, are but the tendencies to union in similar natures.--To the astronomer, the setting sun is as worthy of notice as its golden beams of orient light. 25.-INTIMATING INSTANCES.-Intimating Instances are such as point out things which principally appertain to the uses of life.
26.-SOVEREIGN INSTANCES, such as regard a variety of instances and occur frequently: which includes all the different modes of experimenting, with a knowledge of instruments in every science.
These instances may be thus exhibited :
1. Natural.
1. Simple.
2. Artificial.
1. Continuance.
2. Exclusion.
3. Regulation of Motions.
4. Particular Consents.
5. Compressing, Extending, Agitating.
6. Heat and Cold.
2. Compound and Changing;
of which we take one or two specimens.