suction-pump is but an imitation of the first act of every new-born
infant. Nor do I think it calculated to lessen that infant's
reverence, or to make him a worse citizen, when his riper experience
shows him that the atmosphere was his helper in extracting the first
draught from his mother's breast. The child grows, but is still an
experimenter: he grasps at the moon, and his failure teaches him to
respect distance. At length his little fingers acquire sufficient
mechanical tact to lay hold of a spoon. He thrusts the instrument
into his mouth, hurts his gums, and thus learns the impenetrability of
matter. He lets the spoon fall, and jumps with delight to hear it
rattle against the table. The experiment made by accident is repeated
with intention, and thus the young student receives his first lessons
upon sound and gravitation. There are pains and penalties, however,
in the path of the enquirer: he is sure to go wrong, and Nature is
just as sure to inform him of the fact. He falls downstairs, burns
his fingers, cuts his hand, scalds his tongue, and in this way learns
the conditions of his physical well being. This is Nature's way of
proceeding, and it is wonderful what progress her pupil makes. His
enjoyments for a time are physical, and the confectioner's shop
occupies the foreground of human happiness; but the blossoms of a
finer life are already beginning to unfold themselves, and the
relation of cause and effect dawns upon the boy. He begins to see
that the present condition of things is not final, but depends upon
one that has gone before, and will be succeeded by another. He
becomes a puzzle to himself; and to satisfy his newly-awakened
curiosity, asks all manner of inconvenient questions. The needs and
tendencies of human nature express themselves through these early
yearnings of the child. As thought ripens, he desires to know the
character and causes of the phenomena presented to his observation;
and unless this desire has been granted for the express purpose of
having it repressed, unless the attractions of natural phenomena be
like the blush of the forbidden fruit, conferred merely for the
purpose of exercising our self-denial in letting them alone; we may
fairly claim for the study of Physics the recognition that it answers
to an impulse implanted by nature in the constitution of man.
A few days ago, a Master of Arts, who is still a young man, and
therefore the recipient of a modern education, stated to me that until
he had reached the age of twenty years he had never been taught
anything whatever regarding natural phenomena, or natural law. Twelve
years of his life previously had been spent exclusively among the
ancients. The case, I regret to say, is typical. Now, we cannot,
without prejudice to humanity, separate the present from the past. The
nineteenth century strikes its roots into the centuries gone by, and
draws nutriment from them. The world cannot afford to lose the record
of any great deed or utterance; for such are prolific throughout all
time. We cannot yield the companionship of our loftier brothers of
antiquity,--of our Socrates and Cato,--whose lives provoke us to
sympathetic greatness across the interval of two thousand years. As
long as the ancient languages are the means of access to the ancient
mind, they must ever be of priceless value to humanity; but surely
these avenues might be kept open without making such sacrifices as
that above referred to, universal. We have conquered and possessed
ourselves of continents of land, concerning which antiquity knew
nothing; and if new continents of thought reveal themselves to the
exploring human spirit, shall we not possess them also? In these
latter days, the study of Physics has given us glimpses of the methods
of Nature which were quite hidden from the ancients, and we should be
false to the trust committed to us, if we were to sacrifice the hopes
and aspirations of the Present out of deference to the Past.
The bias of my own education probably manifests itself in a desire I
always feel to seize upon every possible opportunity of checking my
assumptions and conclusions by experience. In the present case, it is
true, your own consciousness might be appealed to in proof of the
tendency of the human mind to inquire into the phenomena presented to
it by the senses; but I trust you will excuse me if, instead of doing
this, I take advantage of the facts which have fallen in my way
through life, referring to your judgment to decide whether such facts
are truly representative and general, and not merely individual and
local.
At an agricultural college in Hampshire, with which I was connected
for some time, and which is now converted into a school for the
general education of youth, a Society was formed among the boys, who
met weekly for the purpose of reading reports and papers upon various
subjects. The Society had its president and treasurer; and abstracts
of its proceedings were published in a little monthly periodical
issuing from the school press. One of the most remarkable features of
these weekly meetings was, that after the general business had been
concluded, each member enjoyed the right of asking questions on any
subject on which he desired information. The questions were either
written out previously in a book, or, if a question happened to
suggest itself during the meeting, it was written upon a slip of paper
and handed in to the Secretary, who afterwards read all the questions
aloud. A number of teachers were usually present, and they and the
boys made a common stock of their wisdom in furnishing replies. As
might be expected from an assemblage of eighty or ninety boys, varying
from eighteen to eight years old, many odd questions were proposed. To
the mind which loves to detect in the tendencies of the young the
instincts of humanity generally, such questions are not without a
certain philosophic interest, and I have therefore thought it not
derogatory to the present course of Lectures to copy a few of them,
and to introduce them here. They run as follows:
What are the duties of the Astronomer Royal?
What is frost?
Why are thunder and lightning more frequent in summer than in winter?
What occasions falling stars?
What is the cause of the sensation called 'pins and needles '?
What is the cause of waterspouts?
What is the cause of hiccup?
If a towel be wetted with water, why does the wet portion become
darker than before?
What is meant by Lancashire witches?
Does the dew rise or fall?
What is the principle of the hydraulic press?
Is there more oxygen in the air in summer than in winter?
What are those rings which we see round the gas and sun?
What is thunder?
How is it that a black hat can be moved by forming round it a magnetic
circle, while a white hat remains stationary?
What is the cause of perspiration?
Is it true that men were once monkeys?
What is the difference between the soul and the mind?
Is it contrary to the rules of Vegetarianism to eat eggs?
In looking over these questions, which were wholly unprompted, and
have been copied almost at random from the book alluded to, we see
that many of them are suggested directly by natural objects, and are
not such as had an interest conferred on them' by previous culture.
Now the fact is beyond the boy's control, and so certainly is the
desire to know its cause. The sole question then is, whether this
desire is to be gratified or not. Who created the fact? Who
implanted the desire? Certainly not man. Who then will undertake to
place himself between the desire and its fulfilment, and proclaim a
divorce between them? Take, for example, the case of the wetted
towel, which at first sight appears to be one of the most unpromising
questions in the list. Shall we tell the proposer to repress his
curiosity, as the subject is improper for him to know, and thus
interpose our wisdom to rescue the boy from the consequences of a wish
which acts to his prejudice? Or, recognising the propriety of the
question, how shall we answer it? It is impossible to answer it
without reference to the laws of optics--without making the boy to
some extent a natural philosopher. You may say that the effect is due
to the reflection of light at the common surface of two media of
different refractive indices. But this answer presupposes on the part
of the boy a knowledge of what reflection and refraction are, or
reduces you to the necessity of explaining them.
On looking more closely into the matter, we find that our wet towel
belongs to a class of phenomena which have long excited the interest
of philosophers. The towel is white for the same reason that snow is
white, that foam is white, that pounded granite or glass is white, and
that the salt we use at table is white. On quitting one medium and
entering another, a portion of light is always reflected, but on this
condition--the media must possess different refractive indices. Thus,
when we immerse a bit of glass in water, light is reflected from the
common surface of both, and it is this light which enables us to see
the glass. But when a transparent solid is immersed in a liquid of
the same refractive index as itself, it immediately disappears. I
remember once dropping the eyeball of an ox into water; it vanished as
if by magic, with the exception of the crystalline lens, and the
surprise was so great as to cause a bystander to suppose that the
vitreous humour had been instantly dissolved. This, however, was not
the case, and a comparison of the refractive index of the humour with
that of water cleared up the whole matter. The indices were
identical, and hence the light pursued its way through both as if they
formed one continuous mass.
In the case of snow, powdered quartz, or salt, we have a transparent
solid mixed with air. At every transition from solid to air, or
from air to solid, a portion of light is reflected, and this takes
place so often that the light is wholly intercepted. Thus from the
mixture of two transparent bodies we obtain an opaque one. Now the
case of the towel is precisely similar. The tissue is composed of
semi-transparent vegetable fibres, with the interstices between them
filled with air; repeated reflection takes place at the limiting
surfaces of air and fibre, and hence the towel becomes opaque like
snow or salt. But if we fill the interstices with water, we diminish
the reflection; a portion of the light is transmitted, and the
darkness of the towel is due to its increased transparency. Thus the
deportment of various minerals, such as hydrophane and tabasheer, the
transparency of tracing paper used by engineers, and many other
considerations of the highest scientific interest, are involved in the
simple enquiry of this unsuspecting little boy.
Again, take the question regarding the rising or falling of the dew--a
question long agitated, and finally set at rest by the beautiful
researches of Wells. I do not think that any boy of average
intelligence will be satisfied with the simple answer that the dew
falls. He will wish to learn how you know that it falls, and, if
acquainted with the notions of the middle ages, he may refer to the
opinion of Father Laurus, that a goose egg filled in the morning with
dew and exposed to the sun, will rise like a balloon--a swan's egg
being better for the experiment than a goose egg. It is impossible to
give the boy a clear notion of the beautiful phenomenon to which his
question refers, without first making him acquainted with the
radiation and conduction of heat. Take, for example, a blade of
grass, from which one of these orient pearls is depending.
During the day the grass, and the earth beneath it, possess a certain
amount of warmth imparted by the sun; during a serene night, heat is
radiated from the surface of the grass into space, and to supply the
loss, there is a flow of heat from the earth to the blade. Thus the
blade loses heat by radiation, and gains heat by conduction. Now, in
the case before us, the power of radiation is great, whereas the power
of conduction is small; the consequence is that the blade loses more
than it gains, and hence becomes more and more refrigerated. The
light vapour floating around the surface so cooled is condensed upon
it, and there accumulates to form the little pearly globe which we
call a dew-drop.
Thus the boy finds the simple and homely fact which addressed his
senses to be the outcome and flower of the deepest laws. The fact
becomes, in a measure, sanctified as an object of thought, and
invested for him with a beauty for evermore. He thus learns that
things which, at first sight, seem to stand isolated and without
apparent brotherhood in Nature are organically united, and finds the
detection of such analogies a source of perpetual delight. To enlist
pleasure on the side of intellectual performance is a point of the
utmost importance; for the exercise of the mind, like that of the
body, depends for its value upon the spirit in which it is
accomplished. Every physician knows that something more than mere
mechanical motion is comprehended under the idea of healthful
exercise--that, indeed, being most healthful which makes us forget all
ulterior ends in the mere enjoyment of it. What, for example, could
be substituted for the action of the playground, where the boy plays
for the mere love of playing, and without reference to physiological
laws; while kindly Nature accomplishes her ends unconsciously, and
makes his very indifference beneficial to him. You may have more
systematic motions, you may devise means for the more perfect traction
of each particular muscle, but you cannot create the joy and gladness
of the game, and where these are absent, the charm and the health of
the exercise are gone. The case is similar with the education of the
mind.
The study of Physics, as already intimated, consists of two processes,
which are complementary to each other--the tracing of facts to their
causes, and the logical advance from the cause to the fact. In the
former process, called _induction_, certain moral qualities come into
play. The first condition of success is patient industry, an honest
receptivity, and a willingness to abandon all preconceived notions,
however cherished, if they be found to contradict the truth. Believe
me, a self-renunciation which has something lofty in it, and of which
the world never hears, is often enacted in the private experience of
the true votary of science. And if a man be not capable of this
self-renunciation--this loyal surrender of himself to Nature and to
fact, he lacks, in my opinion, the first mark of a true philosopher.
Thus the earnest prosecutor of science, who does not work with the
idea of producing a sensation in the world, who loves the truth better
than the transitory blaze of to-day's fame, who comes to his task with
a single eye, finds in that task an indirect means of the highest
moral culture. And although the virtue of the act depends upon its
privacy, this sacrifice of self, this upright determination to accept
the truth, no matter how it may present itself--even at the hands of a
scientific foe, if necessary--carries with it its own reward. When
prejudice is put under foot and the stains of personal bias have been
washed away--when a man consents to lay aside his vanity and to become
Nature's organ--his elevation is the instant consequence of his
humility.
I should not wonder if my remarks provoked a smile, for they seem to
indicate that I regard the man of science as a heroic, if not indeed
an angelic, character; and cases may occur to you which indicate the
reverse. You may point to the quarrels of scientific men, to their
struggles for priority, to that unpleasant egotism which screams
around its little property of discovery like a scared plover about its
young. I will not deny all this; but let it be set down to its proper
account, to the weakness--or, if you will--to the selfishness of Man,
but not to the charge of Physical Science.
The second process in physical investigation is _deduction_, or the
advance of the mind from fixed principles to the conclusions which
flow from them. The rules of logic are the formal statement of this
process, which, however, was practised by every healthy mind before
ever such rules were written. In the study of Physics, induction and
deduction are perpetually wedded to each other. The man observes,
strips facts of their peculiarities of form, and tries to unite them
by their essences; having effected this, he at once deduces, and thus
checks his induction.
Here the grand difference between the methods at present followed, and
those of the ancients, becomes manifest. They were one-sided in these
matters: they omitted the process of induction, and substituted
conjecture for observation. They could never, therefore, fulfil the
mission of Man to 'replenish the earth, and subdue it.' The
subjugation of Nature is only to be accomplished by the penetration of
her secrets and the patient mastery of her laws. This not only
enables us to protect ourselves from the hostile action of natural
forces, but makes them our slaves. By the study of Physics we have
indeed opened to us treasuries of power of which antiquity never
dreamed. But while we lord it over Matter, we have thereby become
better acquainted with the laws of Mind; for to the mental philosopher
the study of Physics furnishes a screen against which the human spirit
projects its own image, and thus becomes capable of self-inspection.
Thus, then, as a means of intellectual culture, the study of Physics
exercises and sharpens observation: it brings the most exhaustive
logic into play: it compares, abstracts, and generalizes, and provides
a mental scenery appropriate to these processes. The strictest
precision of thought is everywhere enforced, and prudence, foresight,
and sagacity are demanded. By its appeals to experiment, it
continually checks itself, and thus walks on a foundation of facts.
Hence the exercise it invokes does not end in a mere game of
intellectual gymnastics, such as the ancients delighted in, but tends
to the mastery of Nature. This gradual conquest of the external
world, and the consciousness of augmented strength which accompanies
it, render the study of Physics as delightful as it is important.
With regard to the effect on the imagination, certain it is that the
cool results of physical induction furnish conceptions which transcend
the most daring flights of that faculty. Take for example the idea of
an all-pervading aether which transmits a tingle, so to speak, to the
finger ends of the universe every time a street lamp is lighted. The
invisible billows of this aether can be measured with the same ease
and certainty as that with which an engineer measures a base and two
angles, and from these finds the distance across the Thames. Now it
is to be confessed that there may be just as little poetry in the
measurement of an aethereal undulation as in that of the river; for
the intellect, during the acts of measurement and calculation,
destroys those notions of size which appeal to the poetic sense. It
is a mistake to suppose, with Dr. Young, that
An undevout astronomer is mad;
there being no necessary connexion between a devout state of mind and
the observations and calculations of a practical astronomer. It is
not until the man withdraws from his calculation, as a painter from
his work, and thus realizes the great idea on which he has been
engaged, that imagination and wonder are excited. There is, I admit,
a possible danger here. If the arithmetical processes of science be
too exclusively pursued, they may impair the imagination, and thus the
study of Physics is open to the same objection as philological,
theological, or political studies, when carried to excess. But even
in this case, the injury done is to the investigator himself: it does
not reach the mass of mankind. Indeed, the conceptions furnished by
his cold unimaginative reckonings may furnish themes for the poet, and
excite in the highest degree that sentiment of wonder which,
notwithstanding all its foolish vagaries, table-turning included, I,
for my part, should be sorry to see banished from the world.
I have thus far dwelt upon the study of Physics as an agent of
intellectual culture; but like other things in Nature, this study
subserves more than a single end. The colours of the clouds delight
the eye, and, no doubt, accomplish moral purposes also, but the
selfsame clouds hold within their fleeces the moisture by which our
fields are rendered fruitful. The sunbeams excite our interest and
invite our investigation; but they also extend their beneficent
influences to our fruits and corn, and thus accomplish, not only
intellectual ends, but minister, at the same time, to our material
necessities. And so it is with scientific research.
While the love of science is a sufficient incentive to the pursuit of
science, and the investigator, in the prosecution of his enquiries, is
raised above all material considerations, the results of his labours
may exercise a potent influence upon the physical condition of the
community. This is the arrangement of Nature, and not that of the
scientific investigator himself; for he usually pursues his object
without regard to its practical applications.
And let him who is dazzled by such applications--who sees in the
steam-engine and the electric telegraph the highest embodiment of
human genius and the only legitimate object of scientific research,
beware of prescribing conditions to the investigator. Let him beware
of attempting to substitute for that simple love with which the votary
of science pursues his task, the calculations of what he is pleased to
call utility. The professed utilitarian is unfortunately, in most
cases, the very last man to see the occult sources from which useful
results are derived. He admires the flower, but is ignorant of the
conditions of its growth. The scientific man must approach Nature in
his own way; for if you invade his freedom by your so-called practical
considerations, it may be at the expense of those qualities on which
his success as a discoverer depends. Let the self-styled practical
man look to those from the fecundity of whose thought be, and
thousands like him, have sprung into existence. Were they inspired in
their first enquiries by the calculations of utility? Not one of
them. They were often forced to live low and lie hard, and to seek
compensation for their penury in the delight which their favourite
pursuits afforded them.
In the words of one well qualified to speak upon this subject, 'I say
not merely look at the pittance of men like John Dalton, or the
voluntary starvation of the late Graff; but compare what is considered
as competency or affluence by your Faradays, Liebigs, and Herschels,
with the expected results of a life of successful commercial
enterprise: then compare the amount of mind put forth, the work done
for society in either case, and you will be constrained to allow that
the former belong to a class of workers who, properly speaking, are
not paid, and cannot be paid for their work, as indeed it is of a sort
to which no payment could stimulate.'
But while the scientific investigator, standing upon the frontiers of
human knowledge, and aiming at the conquest of fresh soil from the
surrounding region of the unknown, makes the discovery of truth his
exclusive object for the time, he cannot but feel the deepest interest
in the practical application of the truth discovered. There is
something ennobling in the triumph of Mind over Matter. Apart even
from its uses to society, there is something elevating in the idea of
Man having tamed that wild force which flashes through the telegraphic
wire, and made it the minister of his will. Our attainments in these
directions appear to be commensurate with our needs. We had already
subdued horse and mule, and obtained from them all the service which
it was in their power to render: we must either stand still, or find
more potent agents to execute our purposes. At this point the
steam-engine appears. These are still new things; it is not long
since we struck into the scientific methods which have produced these
results. We cannot for an instant regard them as the final
achievements of Science, but rather as an earnest of what she is yet
to do. They mark our first great advances upon the dominion of
Nature. Animal strength fails, but here are the forces which hold the
world together, and the instincts and successes of Man assure him that
these forces are his when he is wise enough to command them.