No More Learning

IX. [81] From the two kinds of axioms above specified, arise the two
divisions of philosophy and the sciences, and we will use the commonly
adopted terms which approach the nearest to our meaning, in our own
sense. Let the investigation of forms, which (in reasoning at least,
and after their own laws), are eternal and immutable, constitute
metaphysics,[82] and let the investigation of the efficient cause of
matter, latent process, and latent conformation (which all relate
merely to the ordinary course of nature, and not to her fundamental and
eternal laws), constitute physics. Parallel to these, let there be two
practical divisions; to physics that of mechanics, and to metaphysics
that of magic, in the purest sense of the term, as applied to its ample
means, and its command over nature.

X. The object of our philosophy being thus laid down, we proceed to
precepts, in the most clear and regular order. The signs for the
interpretation of nature comprehend two divisions; the first regards
the eliciting or creating of axioms from experiment, the second the
deducing or deriving of new experiments from axioms. The first admits
of three subdivisions into ministrations. 1. To the senses. 2. To the
memory. 3. To the mind or reason.

For we must first prepare as a foundation for the whole, a complete
and accurate natural and experimental history. We must not imagine or
invent, but discover the acts and properties of nature.

But natural and experimental history is so varied and diffuse, that
it confounds and distracts the understanding unless it be fixed
and exhibited in due order. We must, therefore, form tables and
co-ordinations of instances, upon such a plan, and in such order that
the understanding may be enabled to act upon them.

Even when this is done, the understanding, left to itself and to its
own operation, is incompetent and unfit to construct its axioms without
direction and support. Our third ministration, therefore, must be true
and legitimate induction, the very key of interpretation. We must
begin, however, at the end, and go back again to the others.

XI. The investigation of forms proceeds thus: a nature being given, we
must first present to the understanding all the known instances which
agree in the same nature, although the subject matter be considerably
diversified. And this collection must be made as a mere history, and
without any premature reflection, or too great degree of refinement.
For instance; take the investigation of the form of heat.

_Instances agreeing in the Form of Heat_

1. The rays of the sun, particularly in summer, and at noon.

2. The same reflected and condensed, as between mountains, or along
walls, and particularly in burning mirrors.

3. Ignited meteors.

4. Burning lightning.

5. Eruptions of flames from the cavities of mountains, etc.

6. Flame of every kind.

7. Ignited solids.

8. Natural warm baths.

9. Warm or heated liquids.

10. Warm vapors and smoke; and the air itself, which admits a most
powerful and violent heat if confined, as in reverberating furnaces.

11. Damp hot weather, arising from the constitution of the air, without
any reference to the time of the year.

12. Confined and subterraneous air in some caverns, particularly in
winter.

13. All shaggy substances, as wool, the skins of animals, and the
plumage of birds, contain some heat.

14. All bodies, both solid and liquid, dense and rare (as the air
itself), placed near fire for any time.

15. Sparks arising from the violent percussion of flint and steel.

16. All bodies rubbed violently, as stone, wood, cloth, etc. , so that
rudders, and axles of wheels, sometimes catch fire, and the West
Indians obtain fire by attrition.

17. Green and moist vegetable matter confined and rubbed together,
as roses, peas in baskets; so hay, if it be damp when stacked, often
catches fire.

18. Quicklime sprinkled with water.

19. Iron, when first dissolved by acids in a glass, and without any
application to fire; the same of tin, but not so intensely.

20. Animals, particularly internally; although the heat is not
perceivable by the touch in insects, on account of their small size.

21. Horse dung, and the like excrement from other animals, when fresh.

22. Strong oil of sulphur and of vitriol exhibit the operation of heat
in burning linen.

23. As does the oil of marjoram, and like substances, in burning the
bony substance of the teeth.

24. Strong and well rectified spirits of wine exhibit the same effects;
so that white of eggs when thrown into it grows hard and white, almost
in the same manner as when boiled, and bread becomes burned and brown
as if toasted.

25. Aromatic substances and warm plants, as the dracunculus [arum], old
nasturtium, etc. , which, though they be not warm to the touch (whether
whole or pulverized), yet are discovered by the tongue and palate to be
warm and almost burning when slightly masticated.

26. Strong vinegar and all acids, on any part of the body not clothed
with the epidermis, as the eye, tongue, or any wounded part, or where
the skin is removed, excite a pain differing but little from that
produced by heat.

27. Even a severe and intense cold produces a sensation of burning. [83]

“Nec Boreæ penetrabile frigus adurit. ”

28. Other instances.

We are wont to call this a table of existence and presence.

XII. We must next present to the understanding instances which do not
admit of the given nature, for form (as we have observed) ought no less
to be absent where the given nature is absent, than to be present where
it is present. If, however, we were to examine every instance, our
labor would be infinite.

Negatives, therefore, must be classed under the affirmatives, and the
want of the given nature must be inquired into more particularly in
objects which have a very close connection with those others in which
it is present and manifest. And this we are wont to term a table of
deviation or of absence in proximity.

_Proximate Instances wanting the Nature of Heat_

The rays of the moon, stars, and comets, are not found to be warm to
the touch, nay, the severest cold has been observed to take place
at the full of the moon. Yet the larger fixed stars are supposed to
increase and render more intense the heat of the sun, as he approaches
them, when the sun is in the sign of the Lion, for instance, and in the
dog-days. [84]

The rays of the sun in what is called the middle region of the air
give no heat, to account for which the commonly assigned reason is
satisfactory; namely, that that region is neither sufficiently near to
the body of the sun whence the rays emanate, nor to the earth whence
they are reflected. And the fact is manifested by snow being perpetual
on the tops of mountains, unless extremely lofty. But it is observed,
on the other hand, by some, that at the Peak of Teneriffe, and also
among the Andes of Peru, the tops of the mountains are free from snow,
which only lies in the lower part as you ascend. Besides, the air on
the summit of these mountains is found to be by no means cold, but only
thin and sharp; so much so, that in the Andes it pricks and hurts the
eyes from its extreme sharpness, and even excites the orifice of the
stomach and produces vomiting. The ancients also observed, that the
rarity of the air on the summit of Olympus was such, that those who
ascended it were obliged to carry sponges moistened with vinegar and
water, and to apply them now and then to their nostrils, as the air was
not dense enough for their respiration; on the summit of which mountain
it is also related, there reigned so great a serenity and calm, free
from rain, snow, or wind, that the letters traced upon the ashes of the
sacrifices on the altar of Jupiter, by the fingers of those who had
offered them, would remain undisturbed till the next year. Those even,
who at this day go to the top of the Peak of Teneriffe, walk by night
and not in the daytime, and are advised and pressed by their guides, as
soon as the sun rises, to make haste in their descent, on account of
the danger (apparently arising from the rarity of the atmosphere), lest
their breathing should be relaxed and suffocated. [85]

The reflection of the solar rays in the polar regions is found to
be weak and inefficient in producing heat, so that the Dutch, who
wintered in Nova Zembla, and expected that their vessel would be
freed about the beginning of July from the obstruction of the mass of
ice which had blocked it up, were disappointed and obliged to embark
in their boat. Hence the direct rays of the sun appear to have but
little power even on the plain, and when reflected, unless they are
multiplied and condensed, which takes place when the sun tends more
to the perpendicular; for, then, the incidence of the rays occurs at
more acute angles, so that the reflected rays are nearer to each other,
while, on the contrary, when the sun is in a very oblique position,
the angles of incidence are very obtuse, and the reflected rays at a
greater distance. In the meantime it must be observed, that there may
be many operations of the solar rays, relating, too, to the nature of
heat, which are not proportioned to our touch, so that, with regard to
us, they do not tend to produce warmth, but, with regard to some other
bodies, have their due effect in producing it.

Let the following experiment be made. Take a lens the reverse of a
burning-glass, and place it between the hand and the solar rays, and
observe whether it diminish the heat of the sun as a burning-glass
increases it. For it is clear, with regard to the visual rays, that in
proportion as the lens is made of unequal thickness in the middle and
at its sides, the images appear either more diffused or contracted. It
should be seen, therefore, if the same be true with regard to heat.

Let the experiment be well tried, whether the lunar rays can be
received and collected by the strongest and best burning-glasses, so as
to produce even the least degree of heat. [86] But if that degree be,
perhaps, so subtile and weak, as not to be perceived or ascertained
by the touch, we must have recourse to those glasses which indicate
the warm or cold state of the atmosphere, and let the lunar rays fall
through the burning-glass on the top of this thermometer, and then
notice if the water be depressed by the heat. [87]

Let the burning-glass be tried on warm objects which emit no luminous
rays, as heated but not ignited iron or stone, or hot water, or the
like; and observe whether the heat become increased and condensed, as
happens with the solar rays.

Let it be tried on common flame.

The effect of comets (if we can reckon them among meteors[88]) in
augmenting the heat of the season is not found to be constant or
clear, although droughts have generally been observed to follow them.
However, luminous lines, and pillars, and openings, and the like,
appear more often in winter than in summer, and especially with the
most intense cold but joined with drought. Lightning, and coruscations,
and thunder, however, rarely happen in winter; and generally at the
time of the greatest heats. The appearances we term falling stars are
generally supposed to consist of some shining and inflamed viscous
substance, rather than of violently hot matter; but let this be further
investigated.

Some coruscations emit light without burning, but are never accompanied
by thunder.

Eructations and eruptions of flame are to be found in cold climates
as well as in hot, as in Iceland and Greenland; just as the trees of
cold countries are sometimes inflammable and more pitchy and resinous
than in warm, as the fir, pine, and the like. But the position and
nature of the soil, where such eruptions are wont to happen, is not yet
sufficiently investigated to enable us to subjoin a negative instance
to the affirmative.

All flame is constantly more or less warm, and this instance is not
altogether negative; yet it is said that the ignis fatuus (as it is
called), and which sometimes is driven against walls, has but little
heat; perhaps it resembles that of spirits of wine, which is mild and
gentle. That flame, however, appears yet milder, which in some well
authenticated and serious histories is said to have appeared round the
head and hair of boys and virgins, and instead of burning their hair,
merely to have played about it. And it is most certain that a sort of
flash, without any evident heat, has sometimes been seen about a horse
when sweating at night, or in damp weather. It is also a well known
fact,[89] and it was almost considered as a miracle, that a few years
since a girl’s apron sparkled when a little shaken or rubbed, which
was, perhaps, occasioned by the alum or salts with which the apron
was imbued, and which, after having been stuck together and incrusted
rather strongly, were broken by the friction. It is well known that
all sugar, whether candied or plain, if it be hard, will sparkle when
broken or scraped in the dark. In like manner sea and salt water is
sometimes found to shine at night when struck violently by the oar. The
foam of the sea when agitated by tempests also sparkles at night, and
the Spaniards call this appearance the sea’s lungs. It has not been
sufficiently ascertained what degree of heat attends the flame which
the ancient sailors called Castor and Pollux, and the moderns call
St. Ermus’ fire.

Every ignited body that is red-hot is always warm, although without
flame, nor is any negative instance subjoined to this affirmative.
Rotten wood, however, approaches nearly to it, for it shines at night,
and yet is not found to be warm; and the putrefying scales of fish
which shine in the same manner are not warm to the touch, nor the body
of the glowworm, or of the fly called Lucciola. [90]

The situation and nature of the soil of natural warm baths has not been
sufficiently investigated, and therefore a negative instance is not
subjoined.

To the instances of warm liquids we may subjoin the negative one of the
peculiar nature of liquids in general; for no tangible liquid is known
that is at once warm in its nature and constantly continues warm; but
their heat is only superinduced as an adventitious nature for a limited
time, so that those which are extremely warm in their power and effect,
as spirits of wine, chemical aromatic oils, the oils of vitriol and
sulphur, and the like, and which speedily burn, are yet cold at first
to the touch, and the water of natural baths, poured into any vessel
and separated from its source, cools down like water heated by the
fire. It is, however, true that oily substances are rather less cold
to the touch than those that are aqueous, oil for instance than water,
silk than linen; but this belongs to the table of degrees of cold.

In like manner we may subjoin a negative instance to that of warm
vapor, derived from the nature of vapor itself, as far as we are
acquainted with it. For exhalations from oily substances, though easily
inflammable, are yet never warm unless recently exhaled from some warm
substance.

The same may be said of the instance of air; for we never perceive that
air is warm unless confined or pressed, or manifestly heated by the
sun, by fire, or some other warm body.

A negative instance is exhibited in weather by its coldness with an
east or north wind, beyond what the season would lead us to expect,
just as the contrary takes place with the south or west winds. An
inclination to rain (especially in winter) attends warm weather, and to
frost cold weather.

A negative instance as to air confined in caverns may be observed in
summer. Indeed, we should make a more diligent inquiry into the nature
of confined air. For in the first place the qualities of air in its own
nature with regard to heat and cold may reasonably be the subject of
doubt; for air evidently derives its heat from the effects of celestial
bodies, and possibly its cold from the exhalation of the earth, and
in the mid region of air (as it is termed) from cold vapors and snow,
so that no judgment can be formed of the nature of air by that which
is out of doors and exposed, but a more correct one might be derived
from confined air. It is necessary, however, that the air should be
inclosed in a vessel of such materials as would not imbue it with heat
or cold of themselves, nor easily admit the influence of the external
atmosphere. The experiment should be made, therefore, with an earthen
jar, covered with folds of leather to protect it from the external
air, and the air should be kept three or four days in this vessel well
closed. On opening the jar, the degree of heat may be ascertained
either by the hand or a graduated glass tube.

There is a similar doubt as to whether the warmth of wool, skins,
feathers, and the like, is derived from a slight inherent heat, since
they are animal excretions, or from their being of a certain fat and
oily nature that accords with heat, or merely from the confinement and
separation of air which we spoke of in the preceding paragraph;[91] for
all air appears to possess a certain degree of warmth when separated
from the external atmosphere. Let an experiment be made, therefore,
with fibrous substances of linen, and not of wool, feathers, or silk,
which are animal excretions. For it is to be observed that all powders
(where air is manifestly inclosed) are less cold than the substances
when whole, just as we imagine froth (which contains air) to be less
cold than the liquid itself.

We have here no exactly negative instance, for we are not acquainted
with any body tangible or spirituous which does not admit of heat when
exposed to the fire. There is, however, this difference, that some
admit it more rapidly, as air, oil, and water, others more slowly, as
stone and metals. [92] This, however, belongs to the table of degrees.

No negative is here subjoined, except the remark that sparks are not
kindled by flint and steel, or any other hard substance, unless some
small particles of the stone or metal are struck off, and that the air
never forms them by friction, as is commonly supposed; besides, the
sparks from the weight of the ignited substance have a tendency to
descend rather than to rise, and when extinguished become a sort of
dark ash.

We are of opinion that here again there is no negative; for we are not
acquainted with any tangible body which does not become decidedly warm
by friction, so that the ancients feigned that the gods had no other
means or power of creating heat than the friction of air, by rapid
and violent rotation. On this point, however, further inquiry must be
made, whether bodies projected by machines (as balls from cannon) do
not derive some degree of heat from meeting the air, which renders
them somewhat warm when they fall. The air in motion rather cools
than heats, as in the winds, the bellows, or breath when the mouth is
contracted. The motion, however, in such instances is not sufficiently
rapid to excite heat, and is applied to a body of air, and not to its
component parts, so that it is not surprising that heat should not be
generated.

We must make a more diligent inquiry into this instance; for herbs and
green and moist vegetables appear to possess a latent heat, so small,
however, as not to be perceived by the touch in single specimens, but
when they are united and confined, so that their spirit cannot exhale
into the air, and they rather warm each other, their heat is at once
manifested, and even flame occasionally in suitable substances.

Here, too, we must make a more diligent inquiry; for quicklime, when
sprinkled with water, appears to conceive heat, either from its being
collected into one point (as we observed of herbs when confined), or
from the irritation and exasperation of the fiery spirit by water,
which occasions a conflict and struggle. The true reason will more
readily be shown if oil be used instead of water, for oil will
equally tend to collect the confined spirit, but not to irritate.
The experiment may be made more general, both by using the ashes and
calcined products of different bodies and by pouring different liquids
upon them.

A negative instance may be subjoined of other metals which are more
soft and soluble; for leaf gold dissolved by aqua regia, or lead by
aqua fortis, are not warm to the touch while dissolving, no more is
quicksilver (as far as I remember), but silver excites a slight heat,
and so does copper, and tin yet more plainly, and most of all iron and
steel, which excite not only a powerful heat, but a violent bubbling.
The heat, therefore, appears to be occasioned by the struggle which
takes place when these strong dissolvents penetrate, dig into, and tear
asunder the parts of those substances, while the substances themselves
resist. When, however, the substances yield more easily, scarcely any
heat is excited.

There is no negative instance with regard to the heat of animals,
except in insects (as has been observed), owing to their small size;
for in fishes, as compared with land animals, a lower degree rather
than a deprivation of heat is observable. In plants and vegetables,
both as to their exudations and pith when freshly exposed, there is no
sensible degree of heat. But in animals there is a great difference
in the degree, both in particular parts (for the heat varies near the
heart, the brain, and the extremities) and in the circumstances in
which they are placed, such as violent exercise and fevers.

Here, again, there is scarcely a negative instance. I might add that
the excrements of animals, even when they are no longer fresh, possess
evidently some effective heat, as is shown by their enriching the soil.

Such liquids (whether oily or watery) as are intensely acrid exhibit
the effects of heat, by the separation and burning of bodies after
some little action upon them, yet they are not at first warm to the
touch, but they act according to their affinity and the pores of the
substances to which they are applied; for aqua regia dissolves gold but
not silver--on the contrary, aqua fortis dissolves silver but not gold;
neither of them dissolves glass, and so of the rest.

Let spirits of wine be tried on wood, or butter, wax, or pitch, to see
if this will melt them at all by their heat; for the twenty-fourth
instance shows that they possess properties resembling those of heat in
causing incrustation. Let an experiment also be made with a graduated
glass or calendar,[93] concave at the top, by pouring well-rectified
spirits of wine into the cavity, and covering it up in order that they
may the better retain their heat, then observe whether their heat make
the water descend.

Spices and acrid herbs are sensibly warm to the palate, and still
more so when taken internally; one should see, therefore, on what
other substances they exhibit the effects of heat. Now, sailors tell
us that when large quantities of spices are suddenly opened, after
having been shut up for some time, there is some danger of fever and
inflammation to those who stir them or take them out. An experiment
might, therefore, be made whether such spices and herbs, when produced,
will, like smoke, dry fish and meat hung up over them.

There is an acrid effect and a degree of penetration in cold liquids,
such as vinegar and oil of vitriol, as well as in warm, such as oil of
marjoram and the like; they have, therefore, an equal effect in causing
animated substances to smart, and separating and consuming inanimate
parts. There is not any negative instance as to this, nor does there
exist any animal pain unaccompanied by the sensation of heat.

There are many effects common to cold and heat, however different
in their process; for snowballs appear to burn boys’ hands after
a little time, and cold no less than fire preserves bodies from
putrefaction--besides both heat and cold contract bodies. But it is
better to refer these instances and the like to the investigation of
cold.

XIII. In the third place we must exhibit to the understanding the
instances in which that nature, which is the object of our inquiries,
is present in a greater or less degree, either by comparing its
increase and decrease in the same object, or its degree in different
objects; for since the form of a thing is its very essence, and the
thing only differs from its form as the apparent from the actual
object, or the exterior from the interior, or that which is considered
with relation to man from that which is considered with relation to the
universe; it necessarily follows that no nature can be considered a
real form which does not uniformly diminish and increase with the given
nature. We are wont to call this our Table of Degrees, or Comparative
Instances.

_Table of the Degrees or Comparative Instances of Heat_

We will first speak of those bodies which exhibit no degree of heat
sensible to the touch, but appear rather to possess a potential heat,
or disposition and preparation for it. We will then go on to others,
which are actually warm to the touch, and observe the strength and
degree of it.

1. There is no known solid or tangible body which is by its own nature
originally warm; for neither stone, metal, sulphur, fossils, wood,
water, nor dead animal carcasses are found warm. The warm springs in
baths appear to be heated accidentally, by flame, subterraneous fire
(such as is thrown up by Etna and many other mountains), or by the
contact of certain bodies, as heat is exhibited in the dissolution of
iron and tin. The degree of heat, therefore, in inanimate objects is
not sensible to our touch; but they differ in their degrees of cold,
for wood and metal are not equally cold. [94] This, however, belongs to
the Table of Degrees of Cold.

2. But with regard to potential heat and predisposition to flame, we
find many inanimate substances wonderfully adapted to it, as sulphur,
naphtha, and saltpetre.

3. Bodies which have previously acquired heat, as horse dung from the
animal, or lime, and perhaps ashes and soot from fire, retain some
latent portion of it. Hence distillations and separations of substances
are effected by burying them in horse dung, and heat is excited in
lime by sprinkling it with water (as has been before observed).

4. In the vegetable world we know of no plant, nor part of any plant
(as the exudations or pith) that is warm to man’s touch. Yet (as we
have before observed) green weeds grow warm when confined, and some
vegetables are warm and others cold to our internal touch, _i. e. _, the
palate and stomach, or even after a while to our external skin (as is
shown in plasters and ointments).

5. We know of nothing in the various parts of animals, when dead or
detached from the rest, that is warm to the touch; for horse dung
itself does not retain its heat, unless it be confined and buried. All
dung, however, appears to possess a potential heat, as in manuring
fields; so also dead bodies are endued with this latent and potential
heat to such a degree, that in cemeteries where people are interred
daily the earth acquires a secret heat, which consumes any recently
deposited body much sooner than pure earth; and they tell you that the
people of the East are acquainted with a fine soft cloth, made of the
down of birds, which can melt butter wrapped gently up in it by its own
warmth.

6. Manures, such as every kind of dung, chalk, sea-sand, salt and the
like, have some disposition toward heat.

7.
All putrefaction exhibits some slight degree of heat, though not
enough to be perceptible by the touch; for neither the substances which
by putrefaction are converted into animalculæ,[95] as flesh and cheese,
nor rotten wood which shines in the dark, are warm to the touch. The
heat, however, of putrid substances displays itself occasionally in a
disgusting and strong scent.

8. The first degree of heat, therefore, in substances which are warm
to the human touch appears to be that of animals, and this admits of a
great variety of degrees, for the lowest (as in insects) is scarcely
perceptible, the highest scarcely equals that of the sun’s rays in
warm climates and weather, and is not so acute as to be insufferable
to the hand. It is said, however, of Constantius, and some others of
a very dry constitution and habit of body, that when attacked with
violent fevers, they became so warm as to appear almost to burn the
hand applied to them.

9. Animals become more warm by motion and exercise, wine and feasting,
venery, burning fevers, and grief.

10. In the paroxysm of intermittent fevers the patients are at first
seized with cold and shivering, but soon afterward become more heated
than at first--in burning and pestilential fevers they are hot from the
beginning.

11. Let further inquiry be made into the comparative heat of different
animals, as fishes, quadrupeds, serpents, birds, and also of the
different species, as the lion, the kite, or man; for, according to the
vulgar opinion, fishes are the least warm internally, and birds the
most, particularly doves, hawks, and ostriches.

12. Let further inquiry be made as to the comparative heat in different
parts and limbs of the same animal; for milk, blood, seed, and eggs are
moderately warm, and less hot than the outward flesh of the animal when
in motion or agitated. The degree of heat of the brain, stomach, heart,
and the rest, has not yet been equally well investigated.

13. All animals are externally cold in winter and cold weather, but are
thought to be internally warmer.

14. The heat of the heavenly bodies, even in the warmest climates and
seasons, never reaches such a pitch as to light or burn the driest wood
or straw, or even tinder without the aid of burning-glasses. It can,
however, raise vapor from moist substances.

15. Astronomers tell us that some stars are hotter than others. Mars
is considered the warmest after the Sun, then Jupiter, then Venus. The
Moon and, above all, Saturn, are considered to be cold. Among the fixed
stars Sirius is thought the warmest, then Cor Leonis or Regulus, then
the lesser Dog-star.

16. The sun gives out more heat as it approaches toward the
perpendicular or zenith, which may be supposed to be the case with the
other planets, according to their degree of heat; for instance, that
Jupiter gives out more heat when situated beneath Cancer or Leo than
when he is beneath Capricorn and Aquarius.

17. It is to be supposed that the sun and other planets give more
heat in perigee, from their approximation to the earth, than when in
apogee. But if in any country the sun should be both in its perigee
and nearer to the perpendicular at the same time, it must necessarily
give out more heat than in a country where it is also in perigee,
but situated more obliquely; so that the comparative altitude of the
planets should be observed, and their approach to or declination from
the perpendicular in different countries.

18. The sun and other planets are thought also to give out more heat in
proportion as they are nearer to the larger fixed stars, as when the
sun is in Leo he is nearer Cor Leonis, Cauda Leonis, Spica Virginis,
Sirius, and the lesser Dog-star, than when he is in Cancer, where,
however, he approaches nearer to the perpendicular. It is probable,
also, that the quarters of the heavens produce a greater heat (though
not perceptibly), in proportion as they are adorned with a greater
number of stars, particularly those of the first magnitude.

19. On the whole, the heat of the heavenly bodies is augmented in three
ways: 1. The approach to the perpendicular; 2. Proximity or their
perigee; 3. The conjunction or union of stars.

20. There is a very considerable difference between the degree of heat
in animals, and even in the rays of the heavenly bodies (as they reach
us), and the heat of the most gentle flame, and even of all ignited
substances, nay, liquids, or the air itself when unusually heated by
fire. For the flame of spirit of wine, though diffused and uncollected,
is yet able to set straw, linen, or paper on fire, which animal heat,
or that of the sun, will never accomplish without a burning-glass.

21. There are, however, many degrees of strength and weakness in flame
and ignited bodies: but no diligent inquiry has been made in this
respect, and we must, therefore, pass it hastily over. Of all flames,
that of spirits of wine appears to be the most gentle, except perhaps
the ignis fatuus, or the flashes from the perspiration of animals.
After this we should be inclined to place the flame of light and porous
vegetables, such as straw, reeds, and dried leaves; from which the
flame of hair or feathers differs but little. Then, perhaps, comes
the flame of wood, particularly that which contains but little rosin
or pitch; that of small wood, however (such as is usually tied up in
fagots), is milder than that of the trunks or roots of trees. This can
be easily tried in iron furnaces, where a fire of fagots or branches
of trees is of little service. Next follows the flame of oil, tallow,
wax, and the like oily and fat substances, which are not very violent.
But a most powerful heat is found in pitch and rosin, and a still
greater in sulphur, camphor, naphtha, saltpetre, and salts (after they
have discharged their crude matter), and in their compounds; as in
gunpowder, Greek fire (vulgarly called wild fire), and its varieties,
which possess such a stubborn heat as scarcely to be extinguished by
water.

22. We consider that the flame which results from some imperfect metals
is very strong and active; but on all these points further inquiry
should be made.

23. The flame of vivid lightning appears to exceed all the above, so as
sometimes to have melted even wrought iron into drops, which the other
flames cannot accomplish.

24. In ignited bodies there are different degrees of heat, concerning
which, also, a diligent inquiry has not been made. We consider the
faintest heat to be that of tinder, touchwood, and dry rope match,
such as is used for discharging cannon. Next follows that of ignited
charcoal or cinders, and even bricks, and the like; but the most
violent is that of ignited metals, as iron, copper, and the like.
Further inquiry, however, must be made into this also.

25. Some ignited bodies are found to be much warmer than some flames;
for instance, red hot iron is much warmer, and burns more than the
flame of spirits of wine.

26. Some bodies even not ignited, but only heated by the fire, as
boiling water, and the air confined in reverberatories, surpass in heat
many flames and ignited substances.

27. Motion increases heat,[96] as is shown in the bellows and the
blowpipe; for the harder metals are not dissolved or melted by steady
quiet fire, without the aid of the blowpipe.

28. Let an experiment be made with burning-glasses; in which respect I
have observed, that if a glass be placed at the distance of ten inches,
for instance, from the combustible object, it does not kindle or burn
it so readily, as if the glass be placed at the distance of five inches
(for instance), and be then gradually and slowly withdrawn to the
distance of ten inches. The cone and focus of the rays, however, are
the same, but the mere motion increases the effect of the heat.

29. Conflagrations, which take place with a high wind, are thought to
make greater way against than with the wind, because when the wind
slackens, the flame recoils more rapidly than it advances when the wind
is favorable.

30. Flame does not burst out or arise unless it have some hollow
space to move and exert itself in, except in the exploding flame of
gunpowder, and the like, where the compression and confinement of the
flame increase its fury.

31. The anvil becomes so hot by the hammer, that if it were a thin
plate it might probably grow red, like ignited iron by repeated
strokes. Let the experiment be tried.

32. But in ignited bodies that are porous, so as to leave room for the
fire to move itself, if its motion be prevented by strong compression,
the fire is immediately extinguished; thus it is with tinder, or the
burning snuff of a candle or lamp, or even hot charcoal or cinders;
for when they are squeezed by snuffers, or the foot, and the like, the
effect of the fire instantly ceases.

33. The approach toward a hot body increases heat in proportion to the
approximation; a similar effect to that of light, for the nearer any
object is placed toward the light, the more visible it becomes.

34. The[97] union of different heats increases heat, unless the
substances be mixed; for a large and small fire in the same spot tend
mutually to increase each other’s heat, but lukewarm water poured into
boiling water cools it.

35. The continued neighborhood of a warm body increases heat. For the
heat, which perpetually passes and emanates from it, being mixed with
that which preceded it, multiplies the whole. A fire, for instance,
does not warm a room in half an hour as much as the same fire would in
an hour. This does not apply to light, for a lamp or candle placed in
a spot gives no more light by remaining there, than it did at first.

36. The irritation of surrounding cold increases heat, as may be seen
in fires during a sharp frost. We think that this is owing not merely
to the confinement and compression of the heat (which forms a sort
of union), but also by the exasperation of it, as when the air or a
stick are violently compressed or bent, they recoil, not only to the
point they first occupied, but still further back. Let an accurate
experiment, therefore, be made with a stick, or something of the kind,
put into the flame, in order to see whether it be not sooner burned at
the sides than in the middle of it. [98]

37. There are many degrees in the susceptibility of heat. And, first,
it must be observed how much a low gentle heat changes and partially
warms even the bodies least susceptible of it. For even the heat of the
hand imparts a little warmth to a ball of lead or other metal held a
short time in it; so easily is heat transmitted and excited, without
any apparent change in the body.

38. Of all bodies that we are acquainted with, air admits and loses
heat the most readily, which is admirably seen in weather-glasses,
whose construction is as follows: Take a glass with a hollow belly, and
a thin and long neck; turn it upside down, and place it with its mouth
downward into another glass vessel containing water; the end of the
tube touching the bottom of the vessel, and the tube itself leaning a
little on the edge, so as to be fixed upright. In order to do this more
readily, let a little wax be applied to the edge, not, however, so as
to block up the orifice, lest, by preventing the air from escaping, the
motion, which we shall presently speak of, and which is very gentle and
delicate, should be impeded.

Before the first glass be inserted in the other, its upper part (the
belly) should be warmed at the fire. Then upon placing it as we have
described, the air (which was dilated by the heat), after a sufficient
time has been allowed for it to lose the additional temperature, will
restore and contract itself to the same dimensions as that of the
external or common atmosphere at the moment of immersion, and the water
will be attracted upward in the tube to a proportionate extent. A long
narrow slip of paper should be attached to the tube, divided into as
many degrees as you please. You will then perceive, as the weather
grows warmer or colder, that the air contracts itself into a narrower
space in cold weather and dilates in the warm, which will be exhibited
by the rising of the water as the air contracts itself, and its
depression as the air dilates. The sensibility of the air with regard
to heat or cold is so delicate and exquisite, that it far exceeds the
human touch, so that a ray of sunshine, the heat of the breath, and
much more, that of the hand placed on the top of the tube, immediately
causes an evident depression of the water. We think, however, that the
spirit of animals possesses a much more delicate susceptibility of heat
and cold, only that it is impeded and blunted by the grossness of their
bodies.

39. After air, we consider those bodies to be most sensible of heat,
which have been recently changed and contracted by cold, as snow and
ice; for they begin to be dissolved and melt with the first mild
weather. Next, perhaps, follows quicksilver; then greasy substances,
as oil, butter, and the like; then wood; then water; lastly, stones
and metals, which do not easily grow hot, particularly toward their
centre. [99] When heated, however, they retain their temperature for
a very long time; so that a brick or stone, or hot iron, plunged in
a basin of cold water, and kept there for a quarter of an hour or
thereabout, retains such a heat as not to admit of being touched.

40. The less massive the body is, the more readily it grows warm at the
approach of a heated body, which shows that heat with us is somewhat
averse to a tangible mass. [100]

41. Heat with regard to the human senses and touch is various and
relative, so that lukewarm water appears hot if the hand be cold, and
cold if the hand be hot.

XIV. 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. ”

XV. 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 present 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, according
to the power and strength of the understanding which creates them. But
it is only for God (the bestower and creator of forms), and perhaps
for angels and intelligences, at once to recognize forms affirmatively
at the first glance of contemplation: man, at lest, is unable to do so,
and is only allowed to proceed first by negatives, and then to conclude
with affirmatives, after every species of exclusion.

XVI. We must, therefore, effect a complete solution and separation of
nature; not by fire, but by the mind, that divine fire. The first work
of legitimate induction, in the discovery of forms, 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, while 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 progress.

XVII. 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, as those of a lion, an eagle, a rose, gold, or the
like. The moment for discussing these will arrive 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 abstract or withdraw ourselves from things, and the
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.

But if our forms appear to any one to be somewhat abstracted, from
their mingling and uniting heterogeneous objects (the heat, for
instance, of the heavenly bodies appears to be very different from that
of fire; the fixed red of the rose and the like, from that which is
apparent in the rainbow, or the radiation of opal or the diamond;[101]
death by drowning, from that by burning, the sword, apoplexy, or
consumption; and yet they all agree in the common natures of heat,
redness, and death), let him be assured that his understanding is
inthralled by habit, by general appearances and hypotheses. For it
is most certain that, however heterogeneous and distinct, they agree
in the form 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[102] union of nature, which is the principal
point, we will afterward, in its proper place, treat of the divisions
and ramifications of nature, whether ordinary or internal and more real.

XVIII. We must now offer an example of the exclusion or rejection
of natures found by the tables 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 single instance contained in
them. For it is clear from what has been said that every contradictory
instance destroys a 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.

_An Example of the Exclusive Table, or of the Rejection 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, etc. ) 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 red-hot iron and the flame of
spirits of wine (for the iron is more hot and less bright, while 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,[103] which does not swell in bulk, but
retains the same apparent dimension, reject the absolute expansive
motion of the whole.

11. On account of the expansion of the air in 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 nature.

13. On account of the agreement and conformity of the effects produced
by cold and heat, reject both expansive and contracting motion as
regards the whole.

14. On account of the heat excited by friction, 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 are merely offering
examples, and not perfect tables.

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

XIX. 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 further, 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.

XX. 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
interpretation, or the first vintage.

_The First Vintage of the Form of Heat_

It must be observed that the form of anything 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 are wont to term coruscations, or conspicuous instances. We must
proceed, then, to the first vintage of the form of heat.

From the instances taken collectively, as well as 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 self[104] 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 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
sensation) excites the feeling of heat and of cold; this is shown by
Inst. 41, Tab. 3.