exercise of thought, it is sufficient to cast a rapid glance on the earliest
dawnings of the philosophy of nature, or of the ancient doctrine of the
'Cosmos.' We find even
p 37
among the most savage nations (as my own travels enable me to attest) a
certain vague, terror-stricken sense of the all-powerful unity of natural
forces, and of the existence of an invisible, spiritual essence manifested
in these forces, whether in unfolding the flower and maturing the fruit of
the nutrient tree, in upheaving the soil of the forest, or in rending the
clouds with the might of the storm. We may here trace the revelation of a
bond of union, linking together the visible world and that higher spiritual
world which escapes the grasp of the senses. The two become unconsciously
blended together, developing in the mind of man, as a simple product of
ideal conception and independently of the aid of observation, the first germ
of a 'Philosophy of Nature.'
Among nations least advanced in civilization, the imagination revels in
strange and fantastic creations, and, by its predilection for symbols, alike
influences ideas and language. Instead of examining, men are led to
conjecture, dogmatize, and interpret supposed facts that have never been
observed. The inner world of thought and of feeling does not reflect the
image of the external world in its primitive purity. That which in some
regions of the earth manifested itself as the rudiments of natural
philosophy, only to a small number of persons endowed with superior
intelligence, appears in other regions, and among entire races of men, to be
the result of mystic tendencies and instinctive intuitions. An intimate
communion with nature, and the vivid and deep emotions thus awakened, are
likewise the source from which have sprung the first impulses toward the
worship and deification of the destroying and preserving forces of the
universe. But by degrees, as man, after having passed through the different
gradations of intellectual development, arrives at the free enjoyment of the
regulating power of reflection, and learns by gradual progress, as it were,
to separate the world of ideas from that of sensations, he no longer rests
satisfied merely with a vague presentiment of the harmonious unity of
natural forces; thought begins to fulfill its noble mission; and
observation, aided by reason, endeavors to trace phenomena to the causes
from which they spring.
The history of science teaches us the difficulties that have opposed the
progress of this active spirit of inquiry. Inaccurate and imperfect
observations have led, by false inductions, to the great number of physical
views that have been perpetuated as popular prejudices among all classes of
society. Thus by the side of a solid and scientific knowledge of natural
phenomena there has been preserved a system of the pretended
p 38
results of observation, which is so much the more difficult to shake, as it
denies the validity of the facts by which it may be refuted. This
empiricism, the melancholy heritage transmitted to us from former times,
invariably contends for the truth of its axioms with the arrogance of a
narrow-minded spirit. Physical philosophy, on the other hand, when based
upon science, doubts because it seeks to investigate, distinguishes between
that which is certain and that which is merely probable, and strives
incessantly to perfect theory by extending the circle of observation.
This assemblage of imperfect dogmas, bequeathed by one age to another --
this physical philosophy, which is composed of popular prejudices -- is not
only injurious because it perpetuates error with the obstinacy engendered by
the evidence of ill-observed facts, but also because it hinders the mind
from attaining to higher views of nature. Instead of seeking to discover
the 'mean' or 'medium' point, around which oscillate, in apparent
independence of forces, all the phenomena of the external world, this system
delights in multiplying exceptions to the law, and seeks, amid phenomena and
in organic forms for something beyond the marvel of a regular succession,
and an internal and progressive development. Ever inclined to believe that
the order of nature is disturbed, it refuses to recognize in the present any
analogy with the past, and guided by its own varying hypotheses, seeks at
hazard, either in the interior of the globe or in the regions of space, for
the cause of these pretended perturbations.
It is the special object of the present work to combat those errors which
derive their source from a vicious empiricism and from imperfect inductions.
The higher enjoyments yielded by the study of nature depend upon the
correctness and the depth of our views, and upon the extent of the subjects
that may be comprehended in a single glance. Increased mental cultivation
has given rise, in all classes of society, to an increased desire of
embellishing life by augmenting the mass of ideas, and by multiplying means
for their generalization; and this sentiment fully refutes the vague
accusations advanced against the age in which we live, showing that other
interests, besides the material wants of life, occupy the minds of men.
It is almost with reluctance that I am about to speak of a sentiment, which
appears to arise from narrow-minded views, or from a certain weak and morbid
sentimentality -- I allude to the 'fear' entertained by some persons, that
nature may by degrees lose a portion of the charm and magic of her power,
p 39
as we learn more and more how to unvail her secrets, comprehend the
mechanism of the movements of the heavenly bodies, and estimate numerically
the intensity of natural forces. It is true that, properly speaking, the
forces of nature can only exercise a magical power over us as long as their
action is shrouded in mystery and darkness, and does not admit of being
classed among the conditions with which experience has made us acquainted.
The effect of such a power is, therefore, to excite the imagination, but
that, assuredly, is not the faculty of mind we would evoke to preside over
the laborious and elaborate observations by which we strive to attain to a
knowledge of the greatness and excellence of the laws of the universe.
The astronomer who, by the aid of the heliometer or a double-refracting
prism,* determines the diameter of planetary bodies; who measures patiently
year after year, the meridian altitude and the relative distances of stars,
or who seeks a telescopic comet in a group of nebulae, does not feel his
imagination more excited -- and this is the very guarantee of the precision
of his labors -- than the botanist who counts the divisions of the calyx, or
the number of stamens in a flower, or examines the connected or the separate
teeth of the peristoma surrounding the capsule of a moss. Yet the
multiplied angular measurements on the one hand, and the detail of organic
relations on the other, alike aid in preparing the way for the attainment of
higher views of the laws of the universe.
[Footnote] *Arago's ocular micrometer, a happy improvement upon Rochon's
prismatic or double-refraction micrometer. See M. Mathieu's note in
Delambre's 'Histoire de l'Astronomie au dix-huitieme Siecle', 1827.
We must not confound the disposition of mind in the observer at the time he
is pursuing his labors, with the ulterior greatness of the views resulting
from investigation and the exercise of thought. The physical philosopher
measures with admirable sagacity the waves of light of unequal length which
by interference mutually strengthen or destroy each other, even with respect
to their chemical actions; the astronomer, armed with powerful telescopes,
penetrates the regions of space, contemplates, on the extremest confines of
our solar system, the satellites of Uranus, or decomposes faintly sparkling
points into double stars differing in color. The botanist discovers the
constancy of the gyratory motion of the chara in the greater number of
vegetable cells, and recognizes in the genera and natural families of plants
the intimate relations or organic forms. The vault of heaven, studded with
nebulae
p 40
and stars, and the rich vegetable mantle that covers the soil in the climate
of palms, can not surely fail to produce on the minds of these laborious
observers of nature an impression more imposing and more worthy of the
majesty of creation than on those who are unaccustomed to investigate the
great mutual relations of phenomena. I can not, therefore, agree with Burke
when he says, "it is our ignorance of natural things that causes all our
admiration and chiefly excites our passions."
While the illusion of the senses would make the stars stationary in the
vault of heaven, Astronomy, by her aspiring labors, has assigned indefinite
bounds to space; and if she have set limits to the great nebula to which our
solar system belongs, it has only been to show us in those remote regions of
our optic powers, islet on islet of scattered nebulae. The feeling of the
sublime, so far as it arises from a contemplation of the distance of the
stars, of their greatness and physical extent, reflects itself in the
feeling of the infinite, which belongs to another sphere of ideas included
in the domain of mind. The solemn and imposing impressions excited by this
sentiment are owing to the combination of which we have spoken, and to the
analogous character of the enjoyment and emotions awakened in us, whether we
float on the surface of the great deep, stand on some lonely mountain summit
enveloped in the half-transparent vapory vail of the atmosphere, or by the
aid of powerful optical instruments scan the regions of space, and see the
remote nebulous mass resolve itself into worlds of stars.
The mere accumulation of unconnected observations of details, devoid of
generalization of ideas, may doubtlessly have tended to create and foster
the deeply-rooted prejudice, that the study of the exact sciences must
necessarily chill the feelings, and diminish the nobler enjoyments attendant
upon a contemplation of nature. Those who still cherish such erroneous
views in the present age, and amid the progress of public opinion, and the
advancement of all branches of knowledge, fail in duly appreciating the
value of every enlargement of the sphere of intellect, and the importance of
the detail of isolated facts in leading us on to general results. The fear
of sacrificing the free enjoyment of nature, under the influence of
scientific reasoning, is often associated with an apprehension that every
mind may not be capable of grasping the truths of the philosophy of nature.
It is certainly true that in the midst of the universal fluctuation of
phenomena and vital
p 41
forces -- in that inextricable net-work of organisms by turns developed and
destroyed -- each step that we make in the more intimate knowledge of nature
leads us to the entrance of new labyrinths; but the excitement produced by a
presentiment of discovery, the vague intuition of the mysteries to be
unfolded, and the multiplicity of the paths before us, all tend to stimulate
the exercise of thought in every stage of knowledge. The discovery of each
separate law of nature leads to the establishment of some other more general
law, or at least indicates to the intelligent observer its existence.
Nature, as a celebrated physiologist* has defined it, and as the word was
interpreted by the Greeks and Romans, is "that which is ever growing and
ever unfolding itself in new forms."
[Footnote] *Carus, 'Von den Urtheilen des Knochen und Schalen Gerustes',
1828 6.
The series of organic types becomes extended or perfected in proportion as
hitherto unknown regions are laid open to our view by the labors and
researches of travelers and observers; as living organisms are compared with
those which have disappeared in the great revolutions of our planet; and as
microscopes are made more perfect, and are more extensively and efficiently
employed. In the midst of this immense variety, and this periodic
transformation of animal and vegetable productions, we see incessantly
revealed the primordial mystery of all organic development, that same great
problem of 'metamorphosis' which Göthe has treated with more than common
sagacity, and to the solution of which man is urged by his desire of
reducing vital forms to the smallest number of fundamental types. As men
contemplate the riches of nature, and see the mass of observations
incessantly increasing before them, they become impressed with the intimate
conviction that the surface and the interior of the earth, the depths of the
ocean, and the regions of air will still, when thousands and thousands of
years have passed away, open to the scientific observer untrodden paths of
discovery. The regret of Alexander can not be applied to the progress of
observation and intelligence.*
[footnote] * Plut., in 'Vita Alex. Magni', cap. 7
General considerations, whether they treat of the agglomeration of matter in
the heavenly bodies, or of the geographical distribution of terrestrial
organisms, are not only in themselves more attractive than special studies,
but they also afford superior advantages to those who are unable to devote
much time to occupations of this nature. The different branches of the
study of natural history are only accessible in certain positions of social
life, and do not, at every season
p 42
and in every climate, present like enjoyments. Thus, in the dreary regions
of the north, man is deprived for a long period of the year of the spectacle
presented by the activity of the productive forces of organic nature; and if
the mind be directed to one sole class of objects, the most animated
narratives of voyages in distant lands will fail to interest and attract us,
if they do not touch upon the subjects to which we are most partial.
As the history of nations -- if it were always able to trace events to their
true causes -- might solve the ever-recurring enigma of the oscillations
experienced by the alternately progressive and retrograde movement of human
society, so might also the physical description of the world, the science of
the 'Cosmos', if it were grasped by a powerful intellect, and based upon a
knowledge of all the results of discovery up to a given period, succeed in
dispelling a portion of the contradictions which, at first sight, appear to
arise from the complication or phenomena and the multitude of the
perturbations simultaneously manifested.
The knowledge of the laws of nature, whether we can trace them in the
alternate ebb and flow of the ocean, in the measured path of comets, or in
the mutual attractions of multiple stars, alike increases our sense of the
calm of nature, while the chimera so long cherished by the human mind in its
early and intuitive contemplations, the belief in a "discord of the
elements," seems gradually to vanish in proportion as science extends her
empire. General views lead us habitually to consider each organism as a
part of the entire creation, and to recognize in the plant or the animal not
merely an isolated species, but a form linked in the chain of being to other
forms either living or extinct. They aid us in comprehending the relations
that exist between the most recent discoveries and those which have prepared
the way for them. Although fixed to one point of space, we eagerly grasp at
a knowledge of that which has been observed in different and far-distant
regions. We delight in tracking the course of the bold mariner through seas
of polar ice, or in following him to the summit of that volcano of the
antarctic pole, whose fires may be seen from afar, even at mid-day. It is
by an acquaintance with the results of distant voyages that we may learn to
comprehend some of the marvels of terrestrial magnetism, and be thus led to
appreciate the importance of the establishments of the numerous
observatories which in the present day cover both hemispheres, and are
designed to note
p 43
the simultaneous occurrence of perturbations, and the frequency and duration
of 'magnetic storms.'
Let me be permitted here to touch upon a few points connected with
discoveries, whose importance can only be estimated by those who have
devoted themselves to the study of the physical sciences generally.
Examples chosen from among the phenomena to which special attention has been
directed in recent times, will throw additional light upon the preceding
considerations. Without a preliminary knowledge of the orbits of comets, we
should be unable duly to appreciate the importance attached to the discovery
of one of these bodies, whose elliptical orbit is included in the narrow
limits of our solar system, and which has revealed the existence of an
ethereal fluid, tending to diminish its centrifugal force and the period of
its revolution.
The superficial half-knowledge, so characteristic of the present day, which
leads to the introduction of vaguely comprehended scientific views into
general conversation, also gives rise, under various forms, to the
expression of alarm at the supposed danger of a collision between the
celestial bodies, or of disturbance in the climatic relations of our globe.
These phantoms of the imagination are so much the more injurious as they
derive their source from dogmatic pretensions to true science. The history
of the atmosphere, and of the annual variations of its temperature, extends
already sufficiently far back to show the recurrence of slight disturbances
in the mean temperature of any given place, and thus affords sufficient
guarantee against the exaggerated apprehension of a general and progressive
deterioration of the climates of Europe. Encke's comet, which is one of the
three 'interior comets', completes its course in 1200 days, but from the
form and position of its orbit it is as little dangerous to the earth as
Halley's great comet, whose revolution is not completed in less than
seventy-six years (and which appeared less brilliant in 1835 than it had
done in 1759): the interior comet of Biela intersects the earth's orbit, it
is true, but it can only approach our globe when its proximity to the sun
coincides with our winter solstice.
The quantity of heat received by a planet, and whose unequal distribution
determines the meteorological variations of its atmosphere, depends alike
upon the light-engendering force of the sun; that is to say, upon the
condition of its gaseous coverings, and upon the relative position of the
planet and the central body.
p 44
There are variations, it is true, which, in obedience to the laws of
universal gravitation, affect the form of the earth's orbit and the
inclination of the ecliptic, that is, the angle which the axis of the earth
makes with the plane of its orbit; but these periodical variations are so
slow, and are restricted within such narrow limits, that their thermic
effects would hardly be appreciable by our instruments in many thousands of
years. The astronomical causes of a refrigeration of our globe, and of the
diminution of moisture at its surface, and the nature and frequency of
certain epidemics -- phenomena which are often discussed in the present day
according to the benighted views of the Middle Ages -- ought to be
considered as beyond the range of our experience in physics and chemistry.
Physical astronomy presents us with other phenomena, which can not be fully
comprehended in all their vastness without a previous acquirement of general
views regarding the forces that govern the universe. Such, for instance,
are the innumerable double stars, or rather suns, which revolve round one
common center of gravity, and thus reveal in distant worlds the existence of
the Newtonian law; the larger or smaller number of spots upon the sun, that
is to say, the openings formed through the luminous and opaque atmosphere
surrounding the solid nucleus; and the regular appearance about the 13th of
November and the 11th of August, of shooting stars, which probably form part
of a belt of asteroids, intersecting the earth's orbit, and moving with
planetary velocity.
Descending from the celestial regions to the earth, we would fain inquire
into the relations that exist between the oscillations of the pendulum in
air (the theory of which has been perfected by Bessel) and the density of
our planet; and how the pendulum, acting the part of a plummet, can, to a
certain extent, throw light upon the geological constitution of strata at
great depths? By means of this instrument we are enabled to trace the
striking analogy which exists between the formation of the granular rocks
composing the lava currents ejected from active volcanoes, and those
endogenous masses of granite, porphyry, and serpentine, which, issuing from
the interior of the earth, have broken, as eruptive rocks, through the
secondary strata, and modified them by contact, either in rendering them
harder by the introduction of silex, or reducing them into dolomite, or,
finally, by inducing within them the formation of crystals of the most
varied composition. The elevation of sporadic islands, of
p 45
domes of trachyte, and cones of basalt, by the elastic forces emanating from
the fluid interior of our globe, has led one of the first geologists of the
age, Leopold von Buch, to the theory of the elevation of continents, and of
mountain chains generally. This action of subterranean forces in breaking
through and elevating strata of sedimentary rocks, of which the coast of
Chili, in consequence of a great earthquake, furnished a recent example,
leads to the assumption that the pelagic shells found by M. Bonpland and
myself on the ridge of the Andes, at an elevation of more than 15,000
English feet, may have been conveyed to so extraordinary a position, not by
a rising of the ocean, but by the agency of volcanic forces capable of
elevating into ridges the softened crust of the earth.
I apply the term 'volcanic', in the widest sense of the word, to every
action exercised by the interior of a planet on its external crust. The
surface of our globe, and that of the moon, manifest traces of this action,
which in the former, at least, has varied during the course of ages. Those
who are ignorant of the fact that the internal heat of the earth increases
so rapidly with the increase of depth that granite is in a state of fusion
about twenty or thirty geographical miles below the surface,* can not have a
clear conception of the causes, and the simultaneous occurrence of volcanic
eruptions at places widely removed from one another, or of the extent and
intersection of 'circles of commotion' in earthquakes, or of the uniformity
of temperature, and equality of chemical composition observed in thermal
springs during a long course of years.
[Footnote] * The determinations usually given of the point of fusion are in
general much too high for refracting substances. According to the very
accurate researches of Mitscherlich, the melting point of granite can hardly
exceed 2372 degrees F.
[Dr. Mantell states in 'The Wonders of Geology', 1848, vol. i., p. 34, that
this increase of temperature amounts to 1 degree of Fahrenheit for every
fifty-four feet of vertical depth.] -- Tr.
The quantity of heat peculiar to a planet is, however, a matter of such
importance -- being the result of its primitive condensation, and varying
according to the nature and duration of the radiation -- that the study of
this subject may throw some degree of light on the history of the
atmosphere, and the distribution of the organic bodies imbedded in the solid
crust of the earth. This study enables us to understand how a tropical
temperature, independent of latitude (that is, of the distance from the
poles), may have been produced by deep fissures remaining open, and exhaling
heat from the interior
p 46
of the globe, at a period when the earth's crust was still furrowed and
rent, and only in a state of semi-solidification; and a primordial condition
is thus revealed to us, in which the temperature of the atmosphere, and
climates generally, were owing rather to a liberation of caloric and of
different gaseous emanations (that is to say, rather to the energetic
reaction of the interior on the exterior) than to the position of the earth
with respect to the central body, the sun.