from the great mass of indiscriminative facts, which, as they lie in
nature, are apt to generate confusion by their number, indistinctness
and complication. Such classes of phenomena, as being peculiarly
suggestive of causation, he quaintly classes under the title of
prerogative inquiries, either seduced by the fanciful analogy, which
such instances bore to the _prerogativa centuria_ in the Roman Comitia,
or justly considering them as Herschel supposes to hold a kind of
prerogative dignity from being peculiarly suggestive of causation.
Two high authorities in physical science (v. Herschel, Nat. Phil.,
art. 192; Whewell’s Philosophy of the Inductive Sciences, vol. ii.
p. 243) pronounce these instances of little service in the task of
induction, being for the most part classed not according to the ideas
which they involve, or to any obvious circumstance in the facts of
which they consist, but according to the extent and manner of their
influence upon the inquiry in which they are employed. Thus we
have solitary instances, migrating instances, ostensive instances,
clandestine instances, so termed according to the degree in which
they exhibit, or seem to exhibit, the property, whose nature we would
examine. We have guide-post instances, crucial instances, instances of
the parted road, of the doorway, of the lamp, according to the guidance
they supply to our advance. Whewell remarks that such a classification
is much of the same nature as if, having to teach the art of building,
we were to describe tools with reference to the amount and place of the
work which they must do, instead of pointing out their construction
and use; as if we were to inform the pupil that we must have tools for
lifting a stone up, tools for moving it sidewise, tools for laying it
square, and tools for cementing it firmly. The means are thus lost
in the end, and we reap the fruits of unmethodical arrangement in
the confusion of cross division. In addition, all the instances are
leavened with the error of confounding the laws with the causes of
phenomena, and we are urged to adopt the fundamental error of seeking
therein the universal agents, or general causes of phenomena, without
ascending the gradual steps of intermediate laws.--_Ed._
[108] Of these nine general heads no more than the first is prosecuted
by the author.
[109] This very nearly approaches to Sir I. Newton’s discovery of the
decomposition of light by the prism.
[110] The mineral kingdom, as displaying the same nature in all its
gradations, from the shells so perfect in structure in limestone to the
finer marbles in which their nature gradually disappears, is the great
theatre for instances of migration.--_Ed._
[111] Bacon was not aware of the fact since brought to light by
Römer, that down to fourteen fathoms from the earth’s mean level
the thermometer remains fixed at the tenth degree, but that as the
thermometer descends below that depth the heat increases in a ratio
proportionate to the descent, which happens with little variation in
all climates. Buffon considers this a proof of a central fire in our
planet.--_Ed._
[112] All the diversities of bodies depend upon two principles, _i.e._,
the quantity and the position of the elements that enter into their
composition. The primary difference is not that which depends on the
greatest or least quantity of material elements, but that which depends
on their position. It was the quick perception of this truth that made
Leibnitz say that to complete mathematics it was necessary to join to
the analysis of quantity the analysis of position.--_Ed._
[113] Query?
[114] 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 toward it; the vessel and bubble both
drawing the water that is between them. The latter phenomenon cannot be
explained on Bacon’s hypothesis.
[115] Modern discoveries appear to bear out the sagacity of Bacon’s
remark, and the experiments of Baron Cagnard may be regarded as a first
step toward its full demonstration. After the new facts elicited by
that philosopher, there can be little doubt that the solid, liquid
and aëriform state of bodies are merely stages in a progress of
gradual transition from one extreme to the other, and that however
strongly marked the distinctions between them may appear, they will
ultimately turn out to be separated by no sudden or violent line of
demarcation, but slide into each other by imperceptible gradations.
Bacon’s suggestion, however, is as old as Pythagoras, and perhaps
simultaneous with the first dawn of philosophic reason. The doctrine of
the reciprocal transmutation of the elements underlies all the physical
systems of the ancients, and was adopted by the Epicureans as well as
the Stoics. Ovid opens his last book of the Metamorphoses with the
poetry of the subject, where he expressly points to the hint of Bacon:--
----“Tenuatus in auras
Aëraque humor abit, etc., etc.
* * * * * *
Inde retro redeunt, idemque retexitur ordo.”--xv. 246–249.
and Seneca, in the third book of his Natural Philosophy, quest. iv.,
states the opinion in more precise language than either the ancient
bard or the modern philosopher.--_Ed._
[116] The author’s own system of Memoria Technica may be found in
the De Augmentis, chap. xv. We may add that, notwithstanding Bacon’s
assertion that he intended his method to apply to religion, politics,
and morals, this is the only lengthy illustration he has adduced of any
subject out of the domain of physical science.--_Ed._
[117] The collective instances here meant are no other than general
facts or laws of some degree of generality, and are themselves the
result of induction. For example, the system of Jupiter, or Saturn
with its satellites, is a collective instance, and materially assisted
in securing the admission of the Copernican system. We have here in
miniature, and displayed at one view, a system analogous to that of the
planets about the sun, of which, from the circumstance of our being
involved in it, and unfavorably situated for seeing it otherwise than
in detail, we are incapacitated from forming a general idea, but by
slow and progressive efforts of reason.
But there is a species of collective instance which Bacon does not seem
to have contemplated, in which particular phenomena are presented in
such numbers at once, as to make the induction of their law a matter
of ocular inspection. For example, the parabolic form assumed by a
jet of water spouted out of a hole is a collective instance of the
velocities and directions of the motions of all the particles which
compose it seen together, and which thus leads us without trouble to
recognize the law of the motion of a projectile. Again, the beautiful
figures exhibited by sand strewed on regular plates of glass or metal
set in vibration, are collective instances of an infinite number of
points which remain at rest while the remainder of the plate vibrates,
and in consequence afford us an insight into the law which regulates
their arrangement and sequence throughout the whole surface. The richly
colored lemniscates seen around the optic axis of crystals exposed to
polarized light afford a striking instance of the same kind, pointing
at once to the general mathematical expression of the law which
regulates their production. Such collective instances as these lead us
to a general law by an induction which offers itself spontaneously,
and thus furnish advanced posts in philosophical exploration. The laws
of Kepler, which Bacon ignored on account of his want of mathematical
taste, may be cited as a collective instance. The first is, that the
planets move in elliptical orbits, having the sun for their common
focus. The second, that about this focus the _radius vector_ of each
planet describes equal areas in equal times. The third, that the
squares of the periodic times of the planets are as the cubes of their
mean distance from the sun. This collective instance “opened the way”
to the discovery of the Newtonian law of gravitation.--_Ed._
[118] Is not this very hasty generalization? Do serpents move with four
folds only? Observe also the motion of centipedes and other insects.
[119] Shaw states another point of difference between the objects cited
in the text--animals having their roots within, while plants have
theirs without; for their lacteals nearly correspond with the fibres of
the roots in plants; so that animals seem nourished within themselves
as plants are without.--_Ed._
[120] Bacon falls into an error here in regarding the syllogism as
something distinct from the reasoning faculty, and only one of its
forms. It is not generally true that the syllogism is only a form of
reasoning by which we unite ideas which accord with the middle term.
This agreement is not even essential to accurate syllogisms; when the
relation of the two things compared to the third is one of equality or
similitude, it of course follows that the two things compared may be
pronounced equal, or like to each other. But if the relation between
these terms exist in a different form, then it is not true that the
two extremes stand in the same relation to each other as to the middle
term. For instance, if =A= is double of =B=, and =B= double of =C=,
then =A= is quadruple of =C=. But then the relation of =A= to =C= is
different from that of =A= to =B= and of =B= to =C=.--_Ed._
[121] Comparative anatomy is full of analogies of this kind. Those
between natural and artificial productions are well worthy of
attention, and sometimes lead to important discoveries. By observing
an analogy of this kind between the plan used in hydraulic engines for
preventing the counter-current of a fluid, and a similar contrivance in
the blood vessels, Harvey was led to the discovery of the circulation
of the blood.--_Ed._
[122] This is well illustrated in plants, for the gardener can produce
endless varieties of any known species, but can never produce a new
species itself.
[123] The discoveries of Tournefort have placed moss in the class
of plants. The fish alluded to below are to be found only in the
tropics.--_Ed._
[124] There is, however, no real approximation to birds in either the
flying fish or bat, any more than a man approximates to a fish because
he can swim. The wings of the flying fish and bat are mere expansions
of skin, bearing no resemblance whatever to those of birds.--_Ed._
[125] Seneca was a sounder astronomer than Bacon. He ridiculed the idea
of the motion of any heavenly bodies being irregular, and predicted
that the day would come, when the laws which guided the revolution
of these bodies would be proved to be identical with those which
controlled the motions of the planets. The anticipation, was realized
by Newton.--_Ed._
[126] But see Bacon’s own corollary at the end of the Instances of
Divorce, Aphorism xxxvii. If Bacon’s remark be accepted, the censure
will fall upon Newton and the system so generally received at the
present day. It is, however, unjust, as the centre of which Newton so
often speaks is not a point with an active inherent force, but only
the result of all the particular and reciprocal attractions of the
different parts of the planet acting upon one spot. It is evident, that
if all these forces were united in this centre, that the sum would be
equal to all their partial effects.--_Ed._
[127] Since Newton’s discovery of the law of gravitation, we find that
the attractive force of the earth must extend to an infinite distance.
Bacon himself alludes to the operation of this attractive force at
great distances in the Instances of the Rod, Aphorism xlv.
[128] Snow reflects light, but is not a source of light.
[129] Bacon’s sagacity here foreshadows Newton’s theory of the tides.
[130] The error in the text arose from Bacon’s impression that
the earth was immovable. It is evident, since gravitation acts at
an infinite distance, that no such point could be found; and even
supposing the impossible point of equilibrium discovered, the body
could not maintain its position an instant, but would be hurried, at
the first movement of the heavenly bodies, in the direction of the
dominant gravitating power.--_Ed._
[131] Fly clocks are referred to in the text, not pendulum clocks,
which were not known in England till 1662. The former, though clumsy
and rude in their construction, still embodied sound mechanical
principles. The comparison of the effect of a spring with that of a
weight in producing certain motions in certain times on altitudes and
in mines, has recently been tried by Professors Airy and Whewell in
Dalcoath mine, by means of a pendulum, which is only a weight moved by
gravity, and a chronometer balance moved and regulated by a spring.
In his thirty-seventh Aphorism, Bacon also speaks of gravity as an
incorporeal power, acting at a distance, and requiring time for its
transmission; a consideration which occurred at a later period to
Laplace in one of his most delicate investigations.
Crucial instances, as Herschel remarks, afford the readiest and
securest means of eliminating extraneous causes, and deciding between
the claims of rival hypotheses; especially when these, running parallel
to each other, in the explanation of great classes of phenomena, at
length come to be placed at issue upon a single fact. A curious example
is given by M. Fresnel, as decisive in his mind of the question between
the two great theories on the nature of light, which, since the time
of Newton and Huyghens, have divided philosophers. When two very clean
glasses are laid one on the other, if they be not perfectly flat, but
one or both, in an almost imperceptible degree, convex or prominent,
beautiful and vivid colors will be seen between them; and if these be
viewed through a red glass, their appearance will be that of alternate
dark and bright stripes. These stripes are formed between the two
surfaces in apparent contact, and being applicable on both theories,
are appealed to by their respective supporters as strong confirmatory
facts; but there is a difference in one circumstance, according as
one or other theory is employed to explain them. In the case of the
Huyghenian theory, the intervals between the bright stripes ought to
appear absolutely black, when a prism is used for the upper glass, in
the other half bright. This curious case of difference was tried, as
soon as the opposing consequences of the two theories were noted by
M. Fresnel, and the result is stated by him to be decisive in favor
of that theory which makes light to consist in the vibrations of an
elastic medium.--_Ed._
[132] Bacon plainly, from this passage, was inclined to believe that
the moon, like the comets, was nothing more than illuminated vapor. The
Newtonian law, however, has not only established its solidity, but its
density and weight. A sufficient proof of the former is afforded by the
attraction of the sea, and the moon’s motion round the earth.--_Ed._
[133] Rather the refraction; the sky or air, however, _reflects_ the
blue rays of light.
[134] The polished surface of the glass causes the reflection in this
case, and not the air; and a hat or other black surface put behind the
window in the daytime will enable the glass to reflect distinctly for
the same reason, namely, that the reflected rays are not mixed and
confused with those transmitted from the other side of the window.
[135] These instances, which Bacon seems to consider as a great
discovery, are nothing more than disjunctive propositions combined
with dilemmas. In proposing to explain an effect, we commence with
the enumeration of the different causes which seem connected with
its production; then with the aid of one or more dilemmas, we
eliminate each of the phenomena accidental to its composition, and
conclude with attributing the effect to the residue. For instance, a
certain phenomenon (_a_) is produced either by phenomenon (=B=) or
phenomenon (=C=); but =C= cannot be the cause of _a_, for it is found
in =D=, =E=, =F=, neither of which are connected with _a_. Then the
true cause of phenomenon (_a_) must be phenomenon (=B=).
This species of reasoning is liable to several paralogisms, against
which Bacon has not guarded his readers, from the very fact that he
stumbled into them unwittingly himself. The two principal ones are
false exclusions and defective enumerations. Bacon, in his survey of
the causes which are able to concur in producing the phenomena of the
tides, takes no account of the periodic melting of the Polar ice, or
the expansion of water by the solar heat; nor does he fare better in
his exclusions. For the attraction of the planets and the progression
and retrograde motion communicated by the earth’s diurnal revolution,
can plainly affect the sea together, and have a simultaneous influence
on its surface.
Bacon is hardly just or consistent in his censure of Ramus; the end of
whose dichotomy was only to render reasoning by dilemma, and crucial
instances, more certain in their results, by reducing the divisions
which composed their parts to two sets of contradictory propositions.
The affirmative or negative of one would then necessarily have led to
the acceptance or rejection of the other.--_Ed._
[136] Père Shenier first pointed out the spots on the sun’s disk, and
by the marks which they afforded him, computed its revolution to be
performed in twenty-five days and some hours.--_Ed._
[137] Rust is now well known to be a chemical combination of oxygen
with the metal, and the metal when rusty acquires additional weight.
His theory as to the generation of animals, is deduced from the
erroneous notion of the possibility of spontaneous generation (as it
was termed). See the next paragraph but one.
[138]
“Limus ut hic durescit, et hæc ut cera liquescit
Uno eodemque igni.”--Virg. Ecl. viii.
[139] See Table of Degrees, No. 38.
[140] Riccati, and all modern physicists, discover some portion of
light in every body, which seems to confirm the passage in Genesis that
assigns to this substance priority in creation.--_Ed._
[141] As instances of this kind, which the progress of science since
the time of Bacon affords, we may cite the air-pump and the barometer,
for manifesting the weight and elasticity of air: the measurement
of the velocity of light, by means of the occultation of Jupiter’s
satellites and the aberration of the fixed stars: the experiments
in electricity and galvanism, and in the greater part of pneumatic
chemistry. In all these cases scientific facts are elicited, which
sense could never have revealed to us.--_Ed._
[142] The itinerant instances, as well as frontier instances, are
cases in which we are enabled to trace the general law of continuity
which seems to pervade all nature, and which has been aptly embodied
in the sentence, “natura non agit per saltum.” The pursuit of this law
into phenomena where its application is not at first sight obvious,
has opened a mine of physical discovery, and led us to perceive an
intimate connection between facts which at first seemed hostile to each
other. For example, the transparency of gold-leaf, which permits a
bluish-green light to pass through it, is a frontier instance between
transparent and opaque bodies, by exhibiting a body of the glass
generally regarded the most opaque in nature, as still possessed of
some slight degree of transparency. It thus proves that the quality
of opacity is not a contrary or antagonistic quality to that of
transparency, but only its extreme lowest degree.
[143] Alluding to his theory of atoms.
[144] Observe the approximation to Newton’s theory. The same notion
repeated still more clearly in the ninth motion. Newton believed
that the planets might so conspire as to derange the earth’s annual
revolution, and to elongate the line of the apsides and ellipsis that
the earth describes in its annual revolution round the sun. In the
supposition that all the planets meet on the same straight line, Venus
and Mercury on one side of the sun, and the earth, moon, Mars, Jupiter
and Saturn on the side diametrically opposite; then Saturn would
attract Jupiter, Jupiter Mars, Mars the moon, which must in its turn
attract the earth in proportion to the force with which it was drawn
out of its orbit. The result of this combined action on our planet
would elongate its ecliptic orbit, and so far draw it from the source
of heat, as to produce an intensity of cold destructive to animal
life. But this movement would immediately cease with the planetary
concurrence which produced it, and the earth, like a compressed spring,
bound almost as near to the sun as she had been drawn from it, the
reaction of the heat on its surface being about as intense as the cold
caused by the first removal was severe. The earth, until it gained its
regular track, would thus alternately vibrate between each side of
its orbit, with successive changes in its atmosphere, proportional to
the square of the variation of its distance from the sun. In no place
is Bacon’s genius more conspicuous than in these repeated guesses at
truth. He would have been a strong Copernican, had not Gilbert defended
the system.--_Ed._
[145] This is not true except when the projectile acquires greater
velocity at every successive instant of its course, which is never
the case except with falling bodies. Bacon appears to have been led
into the opinion from observing that gunshots pierce many objects
at a distance from which they rebound when brought within a certain
proximity of contact. This apparent inconsistency, however, arises from
the resistance of the parts of the object, which velocity combined with
force is necessary to overcome.--_Ed._
[146] This passage shows that the pressure of the external atmosphere,
which forces the water into the egg, was not in Bacon’s time
understood.--_Ed._
[147] We have already alluded, in a note prefixed to the same aphorism
of the first book, to Newton’s error of the absolute lightness of
bodies. In speaking again of the volatile or spiritual substances
(Aph. xl. b. ii.) which he supposed with the Platonists and some of the
schoolmen to enter into the composition of every body, he ascribes to
them a power of lessening the weight of the material coating in which
he supposes them inclosed. It would appear from these passages and the
text that Bacon had no idea of the relative density of bodies, and the
capability which some have to diminish the specific gravity of the
heavier substances by the dilation of their parts; or if he had, the
reveries in which Aristotle indulged in treating of the soul, about the
appetency of bodies to fly to kindred substances--flame and spirit to
the sky, and solid opaque substances to the earth, must have vitiated
his mind.--_Ed._
[148] Römer, a Danish astronomer, was the first to demonstrate, by
connecting the irregularities of the eclipses of Jupiter’s satellites
with their distances from the earth, the necessity of time for the
propagation of light. The idea occurred to Dominic Cassini as well as
Bacon, but both allowed the discovery to slip out of their hands.--_Ed._
[149] The author in the text confounds inertness, which is a simple
indifference of bodies to action, with gravity, which is a force acting
always in proportion to their density. He falls into the same error
further on.--_Ed._