by the wonderful exertions of Galileo; by the assistance of which a
nearer intercourse may be opened (as by boats or vessels) between
ourselves and the heavenly objects. For by its aid we are assured
that the Milky Way is but a knot or constellation of small stars,
clearly defined and separate, which the ancients only conjectured to
be the case; whence it appears to be capable of demonstration, that
the spaces of the planetary orbits (as they are termed) are not quite
destitute of other stars, but that the heaven begins to glitter with
stars before we arrive at the starry sphere, although they may be too
small to be visible without the telescope. By the telescope, also, we
can behold the revolutions of smaller stars round Jupiter, whence it
may be conjectured that there are several centres of motion among the
stars. By its assistance, also, the irregularity of light and shade on
the moon’s surface is more clearly observed and determined, so as to
allow of a sort of selenography.[136] By the telescope we see the spots
in the sun, and other similar phenomena; all of which are most noble
discoveries, as far as credit can be safely given to demonstrations
of this nature, which are on this account very suspicious, namely,
that experiment stops at these few, and nothing further has yet
been discovered by the same method, among objects equally worthy of
consideration.
We have instances of the third kind in measuring-rods, astrolabes,
and the like, which do not enlarge, but correct and guide the sight.
If there be other instances which assist the other senses in their
immediate and individual action, yet if they add nothing further to
their information they are not apposite to our present purpose, and we
have therefore said nothing of them.
XL. In the seventeenth rank of prerogative instances we will place
citing instances (to borrow a term from the tribunals), because they
cite those things to appear, which have not yet appeared. We are wont
also to call them invoking instances, and their property is that of
reducing to the sphere of the senses objects which do not immediately
fall within it.
Objects escape the senses either from their distance, or the
intervention of other bodies, or because they are not calculated
to make an impression upon the senses, or because they are not in
sufficient quantity to strike the senses, or because there is not
sufficient time for their acting upon the senses, or because the
impression is too violent, or because the senses are previously filled
and possessed by the object, so as to leave no room for any new motion.
These remarks apply principally to sight, and next to touch, which two
senses act extensively in giving information, and that too upon general
objects, while the remaining three inform us only, as it were, by their
immediate action, and as to specific objects.
There can be no reduction to the sphere of the senses in the first
case, unless in the place of the object, which cannot be perceived
on account of the distance, there be added or substituted some other
object, which can excite and strike the sense from a greater distance,
as in the communication of intelligence by fires, bells, and the like.
In the second case we effect this reduction by rendering those things
which are concealed by the interposition of other bodies, and which
cannot easily be laid open, evident to the senses by means of that
which lies at the surface, or proceeds from the interior; thus the
state of the body is judged of by the pulse, urine, etc.
The third and fourth cases apply to many subjects, and the reduction
to the sphere of the senses must be obtained from every quarter in the
investigation of things. There are many examples. It is obvious that
air, and spirit, and the like, whose whole substance is extremely rare
and delicate, can neither be seen nor touched--a reduction, therefore,
to the senses becomes necessary in every investigation relating to such
bodies.
Let the required nature, therefore, be the action and motion of the
spirit inclosed in tangible bodies; for every tangible body with which
we are acquainted contains an invisible and intangible spirit, over
which it is drawn, and which it seems to clothe. This spirit being
emitted from a tangible substance, leaves the body contracted and dry;
when retained, it softens and melts it; when neither wholly emitted nor
retained, it models it, endows it with limbs, assimilates, manifests,
organizes it, and the like. All these points are reduced to the sphere
of the senses by manifest effects.
For in every tangible and inanimate body the inclosed spirit at first
increases, and as it were feeds on the tangible parts which are most
open and prepared for it; and when it has digested and modified them,
and turned them into spirit, it escapes with them. This formation and
increase of spirit is rendered sensible by the diminution of weight;
for in every desiccation something is lost in quantity, not only of
the spirit previously existing in the body, but of the body itself,
which was previously tangible, and has been recently changed, for the
spirit itself has no weight. The departure or emission of spirit is
rendered sensible in the rust of metals, and other putrefactions of a
like nature, which stop before they arrive at the rudiments of life,
which belong to the third species of process.[137] In compact bodies
the spirit does not find pores and passages for its escape, and is
therefore obliged to force out, and drive before it, the tangible parts
also, which consequently protrude, whence arises rust and the like. The
contraction of the tangible parts, occasioned by the emission of part
of the spirit (whence arises desiccation), is rendered sensible by the
increased hardness of the substance, and still more by the fissures,
contractions, shrivelling, and folds of the bodies thus produced. For
the parts of wood split and contract, skins become shrivelled, and not
only that, but, if the spirit be emitted suddenly by the heat of the
fire, become so hastily contracted as to twist and roll themselves up.
On the contrary, when the spirit is retained, and yet expanded and
excited by heat or the like (which happens in solid and tenacious
bodies), then the bodies are softened, as in hot iron; or flow, as in
metals; or melt, as in gums, wax, and the like. The contrary effects
of heat, therefore (hardening some substances and melting others), are
easily reconciled,[138] because the spirit is emitted in the former,
and agitated and retained in the latter; the latter action is that of
heat and the spirit, the former that of the tangible parts themselves,
after the spirit’s emission.
But when the spirit is neither entirely retained nor emitted, but
only strives and exercises itself, within its limits, and meets with
tangible parts, which obey and readily follow it wherever it leads
them, then follows the formation of an organic body, and of limbs, and
the other vital actions of vegetables and animals. These are rendered
sensible chiefly by diligent observation of the first beginnings, and
rudiments or effects of life in animalculæ sprung from putrefaction, as
in the eggs of ants, worms, mosses, frogs after rain, etc. Both a mild
heat and a pliant substance, however, are necessary for the production
of life, in order that the spirit may neither hastily escape, nor be
restrained by the obstinacy of the parts, so as not to be able to bend
and model them like wax.
Again, the difference of spirit which is important and of effect
in many points (as unconnected spirit, branching spirit, branching
and cellular spirit, the first of which is that of all inanimate
substances, the second of vegetables, and the third of animals), is
placed, as it were, before the eyes by many reducing instances.
Again, it is clear that the more refined tissue and conformation of
things (though forming the whole body of visible or tangible objects)
are neither visible nor tangible. Our information, therefore, must
here also be derived from reduction to the sphere of the senses. But
the most radical and primary difference of formation depends on the
abundance or scarcity of matter within the same space or dimensions.
For the other formations which regard the dissimilarity of the parts
contained in the same body, and their collocation and position, are
secondary in comparison with the former.
Let the required nature then be the expansion or coherence of matter in
different bodies, or the quantity of matter relative to the dimensions
of each. For there is nothing in nature more true than the twofold
proposition--that nothing proceeds from nothing and that nothing is
reduced to nothing, but that the quantum, or sum total of matter, is
constant, and is neither increased nor diminished. Nor is it less true,
that out of this given quantity of matter, there is a greater or less
quantity, contained within the same space or dimensions according to
the difference of bodies; as, for instance, water contains more than
air. So that if any one were to assert that a given content of water
can be changed into an equal content of air, it is the same as if he
were to assert that something can be reduced into nothing. On the
contrary, if any one were to assert that a given content of air can be
changed into an equal content of water, it is the same as if he were
to assert that something can proceed from nothing. From this abundance
or scarcity of matter are properly derived the notions of density and
rarity, which are taken in various and promiscuous senses.
This third assertion may be considered as being also sufficiently
certain; namely, that the greater or less quantity of matter in this or
that body, may, by comparison, be reduced to calculation, and exact, or
nearly exact, proportion. Thus, if one should say that there is such
an accumulation of matter in a given quantity of gold, that it would
require twenty-one times the quantity in dimension of spirits of wine,
to make up the same quantity of matter, it would not be far from the
truth.
The accumulation of matter, however, and its relative quantity, are
rendered sensible by weight; for weight is proportionate to the
quantity of matter, as regards the parts of a tangible substance, but
spirit and its quantity of matter are not to be computed by weight,
which spirit rather diminishes than augments.
We have made a tolerably accurate table of weight, in which we have
selected the weights and size of all the metals, the principal
minerals, stones, liquids, oils, and many other natural and artificial
bodies: a very useful proceeding both as regards theory and practice,
and which is capable of revealing many unexpected results. Nor is this
of little consequence, that it serves to demonstrate that the whole
range of the variety of tangible bodies with which we are acquainted
(we mean tolerably close, and not spongy, hollow bodies, which are for
a considerable part filled with air), does not exceed the ratio of one
to twenty-one. So limited is nature, or at least that part of it to
which we are most habituated.
We have also thought it deserving our industry, to try if we could
arrive at the ratio of intangible or pneumatic bodies to tangible
bodies, which we attempted by the following contrivance. We took a
vial capable of containing about an ounce, using a small vessel in
order to effect the subsequent evaporation with less heat. We filled
this vial, almost to the neck, with spirits of wine, selecting it as
the tangible body which, by our table, was the rarest, and contained a
less quantity of matter in a given space than all other tangible bodies
which are compact and not hollow. Then we noted exactly the weight
of the liquid and vial. We next took a bladder, containing about two
pints, and squeezed all the air out of it, as completely as possible,
and until the sides of the bladder met. We first, however, rubbed the
bladder gently with oil, so as to make it air-tight, by closing its
pores with the oil. We tied the bladder tightly round the mouth of the
vial, which we had inserted in it, and with a piece of waxed thread
to make it fit better and more tightly, and then placed the vial on
some hot coals in a brazier. The vapor or steam of the spirit, dilated
and become aëriform by the heat, gradually swelled out the bladder,
and stretched it in every direction like a sail. As soon as that was
accomplished, we removed the vial from the fire and placed it on a
carpet, that it might not be cracked by the cold; we also pricked the
bladder immediately, that the steam might not return to a liquid state
by the cessation of heat, and confound the proportions. We then removed
the bladder, and again took the weight of the spirit which remained;
and so calculated the quantity which had been converted into vapor, or
an aëriform shape, and then examined how much space had been occupied
by the body in its form of spirits of wine in the vial, and how much,
on the other hand, had been occupied by it in its aëriform shape in the
bladder, and subtracted the results; from which it was clear that the
body, thus converted and changed, acquired an expansion of one hundred
times beyond its former bulk.
Again, let the required nature be heat or cold, of such a degree as
not to be sensible from its weakness. They are rendered sensible by
the thermometer, as we described it above;[139] for the cold and heat
are not actually perceived by the touch, but heat expands and cold
contracts the air. Nor, again, is that expansion or contraction of the
air in itself visible, but the air when expanded depresses the water,
and when contracted raises it, which is the first reduction to sight.
Again, let the required nature be the mixture of bodies; namely,
how much aqueous, oleaginous or spirituous, ashy or salt parts they
contain; or, as a particular example, how much butter, cheese, and whey
there is in milk, and the like. These things are rendered sensible by
artificial and skilful separations in tangible substances; and the
nature of the spirit in them, though not immediately perceptible, is
nevertheless discovered by the various motions and efforts of bodies.
And, indeed, in this branch men have labored hard in distillations
and artificial separations, but with little more success than in
their other experiments now in use; their methods being mere guesses
and blind attempts, and more industrious than intelligent; and what
is worst of all, without any imitation or rivalry of nature, but
rather by violent heats and too energetic agents, to the destruction
of any delicate conformation, in which principally consist the
hidden virtues and sympathies. Nor do men in these separations ever
attend to or observe what we have before pointed out; namely, that
in attacking bodies by fire, or other methods, many qualities are
superinduced by the fire itself, and the other bodies used to effect
the separation, which were not originally in the compound. Hence arise
most extraordinary fallacies; for the mass of vapor which is emitted
from water by fire, for instance, did not exist as vapor or air in the
water, but is chiefly created by the expansion of the water by the heat
of the fire.
So, in general, all delicate experiments on natural or artificial
bodies, by which the genuine are distinguished from the adulterated,
and the better from the more common, should be referred to this
division; for they bring that which is not the object of the senses
within their sphere. They are therefore to be everywhere diligently
sought after.
With regard to the fifth cause of objects escaping our senses, it is
clear that the action of the sense takes place by motion, and this
motion is time. If, therefore, the motion of any body be either so slow
or so swift as not to be proportioned to the necessary momentum which
operates on the senses, the object is not perceived at all; as in the
motion of the hour hand, and that, again, of a musket-ball. The motion
which is imperceptible by the senses from its slowness, is readily and
usually rendered sensible by the accumulation of motion; that which is
imperceptible from its velocity, has not as yet been well measured; it
is necessary, however, that this should be done in some cases, with a
view to a proper investigation of nature.
The sixth case, where the sense is impeded by the power of the object,
admits of a reduction to the sensible sphere, either by removing the
object to a greater distance, or by deadening its effects by the
interposition of a medium, which may weaken and not destroy the object;
or by the admission of its reflection where the direct impression is
too strong, as that of the sun in a basin of water.
The seventh case, where the senses are so overcharged with the object
as to leave no further room, scarcely occurs except in the smell or
taste, and is not of much consequence as regards our present subject.
Let what we have said, therefore, suffice with regard to the reduction
to the sensible sphere of objects not naturally within its compass.
Sometimes, however, this reduction is not extended to the senses of
man, but to those of some other animal, whose senses, in some points,
exceed those of man; as (with regard to some scents) to that of the
dog, and with regard to light existing imperceptibly in the air, when
not illuminated from any extraneous source, to the sense of the cat,
the owl, and other animals which see by night. For Telesius has well
observed, that there appears to be an original portion of light even
in the air itself,[140] although but slight and meagre, and of no use
for the most part to the eyes of men, and those of the generality
of animals; because those animals to whose senses this light is
proportioned can see by night, which does not, in all probability,
proceed from their seeing either without light or by any internal light.
Here, too, we would observe, that we at present discuss only the
wants of the senses, and their remedies; for their deceptions must be
referred to the inquiries appropriated to the senses, and sensible
objects; except that important deception, which makes them define
objects in their relation to man, and not in their relation to the
universe, and which is only corrected by universal reasoning and
philosophy.[141]
XLI. In the eighteenth rank of prerogative instances we will class the
instances of the road, which we are also wont to call itinerant and
jointed instances. They are such as indicate the gradually continued
motions of nature. This species of instances escapes rather our
observation than our senses; for men are wonderfully indolent upon
this subject, consulting nature in a desultory manner, and at periodic
intervals, when bodies have been regularly finished and completed,
and not during her work. But if any one were desirous of examining
and contemplating the talents and industry of an artificer, he would
not merely wish to see the rude materials of his art, and then his
work when finished, but rather to be present while he is at labor,
and proceeding with his work. Something of the same kind should be
done with regard to nature. For instance, if any one investigate the
vegetation of plants, he should observe from the first sowing of any
seed (which can easily be done, by pulling up every day seeds which
have been two, three, or four days in the ground, and examining them
diligently), how and when the seed begins to swell and break, and be
filled, as it were, with spirit; then how it begins to burst the bark
and push out fibres, raising itself a little at the same time, unless
the ground be very stiff; then how it pushes out these fibres, some
downward for roots, others upward for the stem, sometimes also creeping
laterally, if it find the earth open and more yielding on one side, and
the like. The same should be done in observing the hatching of eggs,
where we may easily see the process of animation and organization, and
what parts are formed of the yolk, and what of the white of the egg,
and the like. The same may be said of the inquiry into the formation
of animals from putrefaction; for it would not be so humane to inquire
into perfect and terrestrial animals, by cutting the fœtus from the
womb; but opportunities may perhaps be offered of abortions, animals
killed in hunting, and the like. Nature, therefore, must, as it were,
be watched, as being more easily observed by night than by day: for
contemplations of this kind may be considered as carried on by night,
from the minuteness and perpetual burning of our watch-light.
The same must be attempted with inanimate objects, which we have
ourselves done by inquiring into the opening of liquids by fire.
For the mode in which water expands is different from that observed
in wine, vinegar, or verjuice, and very different, again, from that
observed in milk and oil, and the like; and this was easily seen by
boiling them with slow heat, in a glass vessel, through which the
whole may be clearly perceived. But we merely mention this, intending
to treat of it more at large and more closely when we come to the
discovery of the latent process; for it should always be remembered
that we do not here treat of things themselves, but merely propose
examples.[142]
XLII. In the nineteenth rank of prerogative instances we will class
supplementary or substitutive instances, which we are also wont to call
instances of refuge. They are such as supply information, where the
senses are entirely deficient, and we therefore have recourse to them
when appropriate instances cannot be obtained. This substitution is
twofold, either by approximation or by analogy. For instance, there is
no known medium which entirely prevents the effect of the magnet in
attracting iron--neither gold, nor silver, nor stone, nor glass, wood,
water, oil, cloth, or fibrous bodies, air, flame, or the like. Yet by
accurate experiment, a medium may perhaps be found which would deaden
its effect, more than another comparatively and in degree; as, for
instance, the magnet would not perhaps attract iron through the same
thickness of gold as of air, or the same quantity of ignited as of cold
silver, and so on; for we have not ourselves made the experiment, but
it will suffice as an example. Again, there is no known body which is
not susceptible of heat, when brought near the fire; yet air becomes
warm much sooner than stone. These are examples of substitution by
approximation.
Substitution by analogy is useful, but less sure, and therefore to be
adopted with some judgment. It serves to reduce that which is not the
object of the senses to their sphere, not by the perceptible operations
of the imperceptible body, but by the consideration of some similar
perceptible body. For instance, let the subject for inquiry be the
mixture of spirits, which are invisible bodies. There appears to be
some relation between bodies and their sources or support. Now, the
source of flame seems to be oil and fat; that of air, water, and watery
substances; for flame increases over the exhalation of oil, and air
over that of water. One must therefore consider the mixture of oil and
water, which is manifest to the senses, since that of air and flame in
general escapes the senses. But oil and water mix very imperfectly by
composition or stirring, while they are exactly and nicely mixed in
herbs, blood, and the parts of animals. Something similar, therefore,
may take place in the mixture of flame and air in spirituous
substances, not bearing mixture very well by simple collision, while
they appear, however, to be well mixed in the spirits of plants and
animals.