WAYS AND MEANS OF STUDYING NATURE.
It is desirable that the student of Nature keep well in mind the means
whereby he is able to perceive what goes on in the world about him. He
should understand something as to the nature of his senses, and the
extent to which these capacities enable him to discern the operations
of Nature. Man, in common with his lower kindred, is, by the mechanism
of the body, provided with five somewhat different ways by which he
may learn something of the things about him. The simplest of these
capacities is that of touch, a faculty that is common to the general
surface of the body, and which informs us when the surface is affected
by contact with some external object. It also enables us to discern
differences of temperature. Next is the sense of taste, which is
limited to the mouth and the parts about it. This sense is in a way
related to that of touch, for the reason that it depends on the
contact of our body with material things. Third is the sense of smell,
so closely related to that of taste that it is difficult to draw the
line between the two. Yet through the apparatus of the nose we can
perceive the microscopically small parts of matter borne to us through
the air, which could not be appreciated by the nerves of the mouth.
Fourth in order of scope comes the hearing, which gives us an account
of those waves of matter that we understand as sound. This power is
much more far ranging than those before noted; in some cases, as in
that of the volcanic explosions from the island of Krakatoa, in the
eruption of 1883, the convulsions were audible at the distance of
more than a thousand miles away. The greater cannon of modern days may
be heard at the distance of more than a hundred miles, so that while
the sense of touch, taste, and smell demand contact with the bodies
which we appreciate, hearing gives us information concerning objects
at a considerable distance. Last and highest of the senses, vastly the
most important in all that relates to our understanding of Nature, is
sight, or the capacity which enables us to appreciate the movement of
those very small waves of ether which constitute light. The eminent
peculiarity of sight is that it may give us information concerning
things which are inconceivably far away; it enables us to discern the
light of suns probably millions of times as remote from us as is the
centre of our own solar system.
Although much of the pleasure which the world affords us comes through
the other senses, the basis of almost all our accurate knowledge is
reported by sight. It is true that what we have observed with our eyes
may be set forth in words, and thus find its way to the understanding
through the ears; also that in many instances the sense of touch
conveys information which extends our perceptions in many important
ways; but science rests practically on sight, and on the insight that
comes from the training of the mind which the eyes make possible.
The early inquirers had no resources except those their bodies
afforded; but man is a tool-making creature, and in very early days he
began to invent instruments which helped him in inquiry. The earliest
deliberate study was of the stars. Science began with astronomy, and
the first instruments which men contrived for the purpose of
investigation were astronomical. In the beginning of this search the
stars were studied in order to measure the length of the year, and
also for the reason that they were supposed in some way to control the
fate of men. So far as we know, the first pieces of apparatus for this
purpose were invented in Egypt, perhaps about four thousand years
before the Christian era. These instruments were of a simple nature,
for the magnifying glass was not yet contrived, and so the telescope
was impossible. They consisted of arrangements of straight edges and
divided circles, so that the observers, by sighting along the
instruments, could in a rough way determine the changes in distance
between certain stars, or the height of the sun above the horizon at
the various seasons of the year. It is likely that each of the great
pyramids of Egypt was at first used as an observatory, where the
priests, who had some knowledge of astronomy, found a station for the
apparatus by which they made the observations that served as a basis
for casting the horoscope of the king.
In the progress of science and of the mechanical invention attending
its growth, a great number of inventions have been contrived which
vastly increase our vision and add inconceivably to the precision it
may attain. In fact, something like as much skill and labour has been
given to the development of those inventions which add to our learning
as to those which serve an immediate economic end. By far the greatest
of these scientific inventions are those which depend upon the lens.
By combining shaped bits of glass so as to control the direction in
which the light waves move through them, naturalists have been able to
create the telescope, which in effect may bring distant objects some
thousand times nearer to view than they are to the naked eye; and the
microscope, which so enlarges minute objects as to make them visible,
as they were not before. The result has been enormously to increase
our power of vision when applied to distant or to small objects. In
fact, for purposes of learning, it is safe to say that those tools
have altogether changed man's relation to the visible universe. The
naked eye can see at best in the part of the heavens visible from any
one point not more than thirty thousand stars. With the telescope
somewhere near a hundred million are brought within the limits of
vision. Without the help of the microscope an object a thousandth of
an inch in diameter appears as a mere point, the existence of which we
can determine only under favourable circumstances. With that
instrument the object may reveal an extended and complicated structure
which it may require a vast labour for the observer fully to explore.
Next in importance to the aid of vision above noted come the
scientific tools which are used in weighing and measuring. These
balances and gauges have attained such precision that intervals so
small as to be quite invisible, and weights as slight as a
ten-thousandth of a grain, can be accurately measured. From these
instruments have come all those precise examinations on which the
accuracy of modern science intimately depends. All these instruments
of precision are the inventions of modern days. The simplest
telescopes were made only about two hundred and fifty years ago, and
the earlier compound microscopes at a yet later date. Accurate
balances and other forms of gauges of space, as well as good means of
dividing time, such as our accurate astronomical clocks and
chronometers, are only about a century old. The instruments have made
science accurate, and have immensely extended its powers in nearly all
the fields of inquiry.
Although the most striking modern discoveries are in the field which
was opened to us by the lens in its manifold applications, it is in
the chemist's laboratory that we find that branch of science, long
cultivated, but rapidly advanced only within the last two centuries,
which has done the most for the needs of man. The ancients guessed
that the substances which make up the visible world were more
complicated in their organization than they appear to our vision. They
even suggested the great truth that matter of all kinds is made up of
inconceivably small indivisible bits which they and we term atoms. It
is likely that in the classic days of Greece men began to make simple
experiments of a chemical nature. A century or two after the time of
Mohammed, the Arabians of his faith, a people who had acquired Greek
science from the libraries which their conquests gave them, conducted
extensive experiments, and named a good many familiar chemical
products, such as alcohol, which still bears its Arabic name.
These chemical studies were continued in Europe by the alchemists, a
name also of Arabic origin, a set of inquirers who were to a great
extent drawn away from scientific studies by vain though unending
efforts to change the baser metals into gold and silver, as well as to
find a compound which would make men immortal in the body. By the
invention of the accurate balance, and by patient weighing of the
matters which they submitted to experiment, by the invention of
hypotheses or guesses at truth, which were carefully tested by
experiment, the majestic science of modern chemistry has come forth
from the confused and mystical studies of the alchemists. We have
learned to know that there are seventy or more primitive or apparently
unchangeable elements which make up the mass of this world, and
probably constitute all the celestial spheres, and that these elements
in the form of their separate atoms may group themselves in almost
inconceivably varied combinations. In the inanimate realm these
associations, composed of the atoms of the different substances,
forming what are termed molecules, are generally composed of but few
units. Thus carbonic-acid gas, as it is commonly called, is made up of
an aggregation of molecules, each composed of one atom of carbon and
two of oxygen; water, of two atoms of hydrogen and one of oxygen;
ordinary iron oxide, of two atoms of iron and three of oxygen. In the
realm of organic life, however, these combinations become vastly more
complicated, and with each of them the properties of the substance
thus produced differ from all others. A distinguished chemist has
estimated that in one group of chemical compounds, that of carbon, it
would be possible to make such an array of substances that it would
require a library of many thousand ordinary volumes to contain their
names alone.
It is characteristic of chemical science that it takes account of
actions which are almost entirely invisible. No contrivances have been
or are likely to be invented which will show the observer what takes
place when the atoms of any substance depart from their previous
combination and enter on new arrangements. We only know that under
certain conditions the old atomic associations break up, and new ones
are formed. But though the processes are hidden, the results are
manifest in the changes which are brought about upon the masses of
material which are subjected to the altering conditions. Gradually the
chemists of our day are learning to build up in their laboratories
more and more complicated compounds; already they have succeeded in
producing many of the materials which of old could only be obtained by
extracting them from plants. Thus a number of the perfumes of flowers,
and many of the dye-stuffs which a century ago were extracted from
vegetables, and were then supposed to be only obtainable in that way,
are now readily manufactured. In time it seems likely that important
articles of food, for which we now depend upon the seeds of plants,
may be directly built up from the mineral kingdom. Thus the result of
chemical inquiry has been not only to show us much of the vast realm
of actions which go on in the earth, but to give us control of many of
these movements so that we may turn them to the needs of man.
Animals and plants were at an early day very naturally the subjects of
inquiry. The ancients perceived that there were differences of kind
among these creatures, and even in Aristotle's time the sciences of
zoölogy and botany had attained the point where there were
considerable treatises on those subjects. It was not, however, until a
little more than a century ago that men began accurately to describe
and classify these species of the organic world. Since the time of
Linnæus the growth of our knowledge has gone forward with amazing
swiftness. Within a century we have come to know perhaps a hundred
times as much concerning these creatures as was learned in all the
earlier ages. This knowledge is divisible into two main branches: in
one the inquirers have taken account of the different species, genera,
families, orders, and classes of living forms with such effect that
they have shown the existence at the present time of many hundred
thousand distinct species, the vast assemblage being arranged in a
classification which shows something as to the relationship which the
forms bear to each other, and furthermore that the kinds now living
have not been long in existence, but that at each stage in the history
of the earth another assemblage of species peopled the waters and the
lands.
At first naturalists concerned themselves only with the external forms
of living creatures; but they soon came to perceive that the way in
which these organisms worked, their physiology, in a word, afforded
matters for extended inquiry. These researches have developed the
science of physiology, or the laws of bodily action, on many accounts
the most modern and extensive of our new acquisitions of natural
learning. Through these studies we have come to know something of the
laws or principles by which life is handed on from generation to
generation, and by which the gradations of structure have been
advanced from the simple creatures which appear like bits of animated
jelly to the body and mind of man.
The greatest contribution which modern naturalists have made to
knowledge concerns the origin of organic species. The students of a
century ago believed that all these different kinds had been suddenly
created either through natural law or by the immediate will of God. We
now know that from the beginning of organic life in the remote past to
the present day one kind of animal or plant has been in a natural and
essentially gradual way converted into the species which was to be its
successor, so that all the vast and complicated assemblage of kinds
which now exists has been derived by a process of change from the
forms which in earlier ages dwelt upon this planet. The exact manner
in which these alterations were produced is not yet determined, but in
large part it has evidently been brought about by the method indicated
by Mr. Darwin, through the survival of the fittest individuals in the
struggle for existence.
Until men came to have a clear conception as to the spherical form of
the earth, it was impossible for them to begin any intelligent
inquiries concerning its structure or history. The Greeks knew the
earth to be a sphere, but this knowledge was lost among the early
Christian people, and it was not until about four hundred years ago
that men again came to see that they dwelt upon a globe. On the basis
of this understanding the science of geology, which had in a way been
founded by the Greeks, was revived. As this science depends upon the
knowledge which we have gained of astronomy, physics, chemistry, and
biology, all of which branches of learning have to be used in
explaining the history of the earth, the advance which has been made
has been relatively slow. Geology as a whole is the least perfectly
organized of all the divisions of learning. A special difficulty
peculiar to this science has also served to hinder its development.
All the other branches of learning deal mainly, if not altogether,
with the conditions of Nature as they now exist. In this alone is it
necessary at every step to take account of actions which have been
performed in the remote past.
It is an easy matter for the students of to-day to imagine that the
earth has long endured; but to our forefathers, who were educated in
the view that it had been brought from nothingness into existence
about seven thousand years ago, it was most difficult and for a time
impossible to believe in its real antiquity. Endeavouring, as they
naturally did, to account for all the wonderful revolutions, the
history of which is written in the pages of the great stone book, the
early geologists supposed this planet to have been the seat of
frequent and violent changes, each of which revolutionized its shape
and destroyed its living tenants. It was only very gradually that
they became convinced that a hundred million years or more have
elapsed since the dawn of life on the earth, and that in this vast
period the march of events has been steadfast, the changes taking
place at about the same rate in which they are now going on. As yet
this conception as to the history of our sphere has not become the
general property of the people, but the fact of it is recognised by
all those who have attentively studied the matter. It is now as well
ascertained as any of the other truths which science has disclosed to
us.
It is instructive to note the historic outlines of scientific
development. The most conspicuous truth which this history discloses
is that all science has had its origin and almost all its development
among the peoples belonging to the Aryan race. This body of folk
appears to have taken on its race characteristics, acquired its
original language, its modes of action, and the foundations of its
religion in that part of northern Europe which is about the Baltic
Sea. Thence the body of this people appear to have wandered toward
central Asia, where after ages of pastoral life in the high table
lands and mountains of their country it sent forth branches to India,
Asia Minor and Greece, to Persia, and to western Europe. It seems ever
to have been a characteristic of these Aryan peoples that they had an
extreme love for Nature; moreover, they clearly perceived the need of
accounting for the things that happened in the world about them. In
general they inclined to what is called the pantheistic explanation of
the universe. They believed a supreme God in many different forms to
be embodied in all the things they saw. Even their own minds and
bodies they conceived as manifestations of this supreme power. Among
the Aryans who came to dwell in Europe and along the eastern
Mediterranean this method of explaining Nature was in time changed to
one in which humanlike gods were supposed to control the visible and
invisible worlds. In that marvellous centre of culture which was
developed among the Greeks this conception of humanlike deities was in
time replaced by that of natural law, and in their best days the
Greeks were men of science essentially like those of to-day, except
that they had not learned by experience how important it was to
criticise their theories by patiently comparing them with the facts
which they sought to explain. The last of the important Greek men of
science, Strabo, who was alive when Christ was born, has left us
writings which in quality are essentially like many of the able works
of to-day. But for the interruption in the development of Greek
learning, natural science would probably have been fifteen hundred
years ahead of its present stage. This interruption came in two ways.
In one, through the conquest of Greece and the destruction of its
intellectual life by the Romans, a people who were singularly
incapable of appreciating natural science, and who had no other
interest in it except now and then a vacant and unprofitable curiosity
as to the processes of the natural world. A second destructive
influence came through the fact that Christianity, in its energetic
protest against the sins of the pagan civilization, absolutely
neglected and in a way despised all forms of science.
The early indifference of Christians to natural learning is partly to
be explained by the fact that their religion was developed among the
Hebrews, a people remarkable for their lack of interest in the
scientific aspects of Nature. To them it was a sufficient explanation
that one omnipotent God ruled all things at his will, the heavens and
the earth alike being held in the hollow of his hand.
Finding the centre of its development among the Romans, Christianity
came mainly into the control of a people who, as we have before
remarked, had no scientific interest in the natural world. This
condition prolonged the separation of our faith from science for
fifteen hundred years after its beginning. In this time the records of
Greek scientific learning mostly disappeared. The writings of
Aristotle were preserved in part for the reason that the Church
adopted many of his views concerning questions in moral philosophy and
in politics. The rest of Greek learning was, so far as Europe was
concerned, quite neglected.
A large part of Greek science which has come down to us owes its
preservation to a very singular incident in the history of learning.
In the ninth century, after the Arabs had been converted to
Mohammedanism, and on the basis of that faith had swiftly organized a
great and cultivated empire, the scholars of that folk became deeply
interested in the remnants of Greek learning which had survived in the
monastic and other libraries about the eastern Mediterranean. So
greatly did they prize these records, which were contemned by the
Christians, that it was their frequent custom to weigh the old
manuscripts in payment against the coin of their realm. In astronomy,
mathematics, chemistry, and geology the Arabian students, building on
the ancient foundations, made notable and for a time most important
advances. In the tenth century of our era they seemed fairly in the
way to do for science what western Europe began five centuries later
to accomplish. In the fourteenth century the centre of Mohammedan
strength was transferred from the Arabians to the Turks, from a people
naturally given to learning to a folk of another race, who despised
all such culture. Thenceforth in place of the men who had treasured
and deciphered with infinite pains all the records of earlier
learning, the followers of Mohammed zealously destroyed all the
records of the olden days. Some of these records, however, survived
among the Arabs of Spain, and others were preserved by the Christian
scholars who dwelt in Byzantium, or Constantinople, and were brought
into western Europe when that city was captured by the Turks in the
fifteenth century.
Already the advance of the fine arts in Italy and the general tendency
toward the study of Nature, such as painting and sculpture indicate,
had made a beginning, or rather a proper field for a beginning, of
scientific inquiry. The result was a new interest in Greek learning in
all its branches, and a very rapid awakening of the scientific spirit.
At first the Roman Church made no opposition to this new interest
which developed among its followers, but in the course of a few years,
animated with the fear that science would lead men to doubt many of
the dogmas of the Church, it undertook sternly to repress the work of
all inquirers.
The conflict between those of the Roman faith and the men of science
continued for above two hundred years. In general, the part which the
Church took was one of remonstrance, but in a few cases the spirit of
fanaticism led to the persecution of the men who did not obey its
mandates and disavow all belief in the new opinions which were deemed
contrary to the teachings of Scripture. The last instance of such
oppression occurred in France in the year 1756, when the great Buffon
was required to recant certain opinions concerning the antiquity of
the earth which he had published in his work on Natural History. This
he promptly did, and in almost servile language withdrew all the
opinions to which the fathers had objected. A like conflict between
the followers of science and the clerical authorities occurred in
Protestant countries. Although in no case were the men of science
physically tortured or executed for their opinions, they were
nevertheless subjected to great religious and social pressure: they
were almost as effectively disciplined as were those who fell under
the ban of the Roman Church.
Some historians have criticised the action of the clerical authorities
toward science as if the evil which was done had been performed in our
own day. It should be remembered, however, that in the earlier
centuries the churches regarded themselves as bound to protect all men
from the dangers of heresy. For centuries in the early history of
Christianity the defenders of the faith had been engaged in a
life-and-death struggle with paganism, the followers of which held all
that was known of Nature. Quite naturally the priestly class feared
that the revival of scientific inquiry would bring with it the evils
from which the world had suffered in pagan times. There is no doubt
that these persecutions of science were done under what seemed the
obligations of duty. They may properly be explained particularly by
men of science as one of the symptoms of development in the day in
which they were done. It is well for those who harshly criticise the
relations of the Church to science to remember that in our own
country, about two centuries ago, among the most enlightened and
religious people of the time, Quakers were grievously persecuted, and
witches hanged, all in the most dutiful and God-fearing way. In
considering these relations of science to our faith, the matter should
be dealt with in a philosophical way, and with a sense of the
differences between our own and earlier ages.
To the student of the relations between Christianity and science it
must appear doubtful whether the criticism or the other consequences
which the men of science had to meet from the Church was harmful to
their work. The early naturalists, like the Greeks whom they followed,
were greatly given to speculations concerning the processes of Nature,
which, though interesting, were unprofitable. They also showed a
curious tendency to mingle their scientific speculations with ancient
and base superstitions. They were often given to the absurdity
commonly known as the "black art," or witchcraft, and held to the
preposterous notions of the astrologists. Even the immortal astronomer
Kepler, who lived in the sixteenth century, was a professional
astrologer, and still held to the notion that the stars determined the
destiny of men. Many other of the famous inquirers in those years
which ushered in modern science believed in witchcraft. Thus for a
time natural learning was in a way associated with ancient and
pernicious beliefs which the Church was seeking to overthrow. One
result of the clerical opposition to the advancement of science was
that its votaries were driven to prove every step which led to their
conclusions. They were forced to abandon the loose speculation of
their intellectual guides, the Greeks, and to betake themselves to
observation. Thus a part of the laborious fact-gathering habit on
which the modern advance of science has absolutely depended was due to
the care which men had to exercise in face of the religious
authorities.
In our own time, in the latter part of the nineteenth century, the
conflict between the religious authority and the men of science has
practically ceased. Even the Roman Church permits almost everywhere an
untrammelled teaching of the established learning to which it was at
one time opposed. Men have come to see that all truth is accordant,
and that religion has nothing to fear from the faithful and devoted
study of Nature.
The advance of science in general in modern times has been greatly due
to the development of mechanical inventions. Among the ancients, the
tools which served in the arts were few in number, and these of
exceeding simplicity. So far as we can ascertain, in the five hundred
years during which the Greeks were in their intellectual vigour, not
more than half a dozen new machines were invented, and these were
exceedingly simple. The fact seems to be that a talent for mechanical
invention is mainly limited to the peoples of France, Germany, and of
the English-speaking folk. The first advances in these contrivances
were made in those countries, and all our considerable gains have come
from their people. Thus, while the spirit of science in general is
clearly limited to the Aryan folk, that particular part of the motive
which leads to the invention of tools is restricted to western and
northern Europe, to the people to whom we give the name of Teutonic.
Mechanical inventions have aided the development of our sciences in
several ways. They have furnished inquirers with instruments of
precision; they have helped to develop accuracy of observation; best
of all, they have served ever to bring before the attention of men a
spectacle of the conditions in Nature which we term cause and effect.
The influence of these inventions on the development of learning has
been particularly great where the machines, such as our wind and water
mills, and our steam engine, make use of the forces of Nature,
subjugating them to the needs of man. Such instruments give an
unending illustration as to the presence in Nature of energy. They
have helped men to understand that the machinery of the universe is
propelled by the unending application of power. It was, in fact,
through such machines that men of science first came to understand
that energy, manifested in the natural forces, is something that
eternally endures; that we may change its form in our arts as its form
is changed in the operations of Nature, but the power endures forever.
It is interesting to note that the first observation which led to this
most important scientific conclusion that energy is indestructible
however much it may change its form, was made by an American, Benjamin
Thompson, who left this country at the time of the Revolution, and
after a curious life became the executive officer, and in effect king,
of Bavaria. While engaged in superintending the manufacture of cannon,
he observed that in boring out the barrel of the gun an amount of heat
was produced which evaporated a certain amount of water. He therefore
concluded that the energy required to do the boring of the metal
passed into the state of heat, and thus only changed its state, in no
wise disappearing from the earth. Other students pursuing the same
line of inquiry have clearly demonstrated what is called the law of
the conservation of energy, which more than anything has helped us to
understand the large operations of Nature. Through these studies we
have come to see that, while the universe is a place of ceaseless
change, the quantities of energy and of matter remain unaltered.
The foregoing brief sketch, which sets forth some of the important
conditions which have affected the development of science, may in a
way serve to show the student how he can himself become an interpreter
of Nature. The evidence indicates that the people of our race have
been in a way chosen among all the varieties of mankind to lead in
this great task of comprehending the visible universe. The facts,
moreover, show that discovery usually begins with the interest which
men feel in the world immediately about them, or which is presented to
their senses in a daily spectacle. Thus Benjamin Franklin, in the
midst of a busy life, became deeply interested in the phenomena of
lightning, and by a very simple experiment proved that this wonder of
the air was due to electrical action such as we may arouse by rubbing
a stick of sealing-wax or a piece of amber with a cloth. All
discoveries, in a word, have had their necessary beginnings in an
interest in the facts which daily experience discloses. This desire to
know something more than the first sight exhibits concerning the
actions in the world about us is native in every human soul--at least,
in all those who are born with the heritage of our race. It is
commonly strong in childhood; if cultivated by use, it will grow
throughout a lifetime, and, like other faculties, becomes the stronger
and more effective by the exertions which it inspires. It is therefore
most important that every one should obey this instinctive command to
inquiry, and organize his life and work so that he may not lose but
gain more and more as time goes on of this noble capacity to
interrogate and understand the world about him.
It is best that all study of Nature should begin not in laboratories,
nor with the things which are remote from us, but in the field of
Nature which is immediately about us. The student, even if he dwell in
the unfavourable conditions of a great city, is surrounded by the
world which has yielded immeasurable riches in the way of learning,
which he can appropriate by a little study. He can readily come to
know something of the movements of the air; the buildings will give
him access to a great many different kinds of stone; the smallest
park, a little garden, or even a few potted plants and captive
animals, may tell him much concerning the forms and actions of living
beings. By studying in this way he can come to know something of the
differences between things and their relations to each other. He will
thus have a standard by which he can measure and make familiar the
body of learning concerning Nature which he may find in books. From
printed pages alone, however well they be written, he can never hope
to catch the spirit that animates the real inquirer, the true lover of
Nature.
On many accounts the most attractive way of beginning to form the
habit of the naturalist is by the study of living animals and plants.
To all of us life adds interest, and growth has a charm. Therefore it
is well for the student to start on the way of inquiry by watching the
actions of birds and insects or by rearing plants. It is fortunate if
he can do both these agreeable things. When the habit of taking an
account of that most important part of the world which is immediately
about him has been developed in the student, he may profitably proceed
to acquire the knowledge of the invisible universe which has been
gathered by the host of inquirers of his race. However far he
journeys, he should return to the home world that lies immediately and
familiarly about him, for there alone can he acquire and preserve that
personal acquaintance with things which is at once the inspiration and
the test of all knowledge.
Along with this study of the familiar objects about us the student may
well combine some reading which may serve to show him how others have
been successful in thus dealing with Nature at first hand. For this
purpose there are, unfortunately, but few works which are well
calculated to serve the needs of the beginner. Perhaps the best
naturalist book, though its form is somewhat ancient, is White's
Natural History of Selborne. Hugh Miller's works, particularly his Old
Red Sandstone and My Schools and Schoolmasters, show well how a man
may become a naturalist under difficulties. Sir John Lubbock's studies
on Wasps, and Darwin's work on Animals and Plants under Domestication
are also admirable to show how observation should be made. Dr. Asa
Gray's little treatise on How Plants Grow will also be useful to the
beginner who wishes to approach botany from its most attractive
side--that of the development of the creature from the seed to seed.
There is another kind of training which every beginner in the art of
observing Nature should obtain, and which many naturalists of repute
would do well to give themselves--namely, an education in what we may
call the art of distance and geographical forms. With the primitive
savage the capacity to remember and to picture to the eye the shape of
a country which he knows is native and instinctive. Accustomed to
range the woods, and to trust to his recollection to guide him through
the wilderness to his home, the primitive man develops an important
art which among civilized people is generally dormant. In fact, in our
well-trodden ways people may go for many generations without ever
being called upon to use this natural sense of geography. The easiest
way to cultivate the geographic sense is by practising the art of
making sketch maps. This the student, however untrained, can readily
do by taking first his own dwelling house, on which he should practise
until he can readily from memory make a tolerably correct and
proportional plan of all its rooms. Then on a smaller scale he should
begin to make also from recollection a map showing the distribution of
the roads, streams, and hills with which his daily life makes him
familiar. From time to time this work from memory should be compared
with the facts. At first the record will be found to be very poor, but
with a few months of occasional endeavour the observer will find that
his mind takes account of geographic features in a way it did not
before, and, moreover, that his mind becomes enriched with
impressions of the country which are clear and distinct, in place of
the shadowy recollections which he at first possessed.
When the student has attained the point where, after walking or riding
over a country, he can readily recall its physical features of the
simpler sort, he will find it profitable to undertake the method of
mapping with contour lines--that is, by pencilling in indications to
show the exact shape of the elevations and depressions. The principle
of contour lines is that each of them represents where water would
come against the slope if the area were sunk step by step below the
sea level--in other words, each contour line marks the intersection of
a horizontal plane with the elevation of the country. Practice on this
somewhat difficult task will soon give the student some idea as to the
complication of the surface of a region, and afford him the basis for
a better understanding of what geography means than all the reading he
can do will effect. It is most desirable that training such as has
been described should be a part of our ordinary school education.
Very few people have clear ideas of distances. Even the men whose
trade requires some such knowledge are often without that which a
little training could give them. Without some capacity in this
direction, the student is always at a disadvantage in his contact with
Nature. He can not make a record of what he sees as long as the
element of horizontal and vertical distance is not clearly in mind. To
attain this end the student should begin by pacing some length of road
where the distances are well known. In this way he will learn the
length of his step, which with a grown man generally ranges between
two and a half and three feet. Learning the average length of his
stride by frequent counting, it is easy to repeat the trial until one
can almost unconsciously keep the count as he walks. Properly to
secure the training of this sort the observer should first attentively
look across the distance which is to be determined. He should notice
how houses, fences, people, and trees appear at that distance. He will
quickly perceive that each hundred feet of additional interval
somewhat changes their aspect. In training soldiers to measure with
the eye the distances which they have to know in order effectively to
use the modern weapons of war, a common device is to take a squad of
men, or sometimes a company, under the command of an officer, who
halts one man at each hundred yards until the detachment is strung out
with that interval as far as the eye can see them. The men then walk
to and fro so that the troops who are watching them may note the
effects of increased distance on their appearance, whether standing or
in motion. At three thousand yards a man appears as a mere dot, which
is not readily distinguishable. Schoolboys may find this experiment
amusing and instructive.
After the student has gained, as he readily may, some sense of the
divisions of distance within the range of ordinary vision, he should
try to form some notion of greater intervals, as of ten, a hundred,
and perhaps a thousand miles. The task becomes more difficult as the
length of the line increases, but most persons can with a little
address manage to bring before their eyes a tolerably clear image of a
hundred miles of distance by looking from some elevation which
commands a great landscape. It is doubtful, however, whether the
best-trained man can get any clear notion of a thousand miles--that
is, can present it to himself in imagination as he may readily do with
shorter intervals.
The most difficult part of the general education which the student has
to give himself is begun when he undertakes to picture long intervals
of time. Space we have opportunities to measure, and we come in a way
to appreciate it, but the longest lived of men experiences at most a
century of life, and this is too small a measure to give any notion as
to the duration of such great events as are involved in the history of
the earth, where the periods are to be reckoned by the millions of
years. The only way in which we can get any aid in picturing to
ourselves great lapses of time is by expressing them in units of
distance. Let a student walk away on a straight road for the distance
of a mile; let him call each step a year; when he has won the first
milestone, he may consider that he has gone backward in time to the
period of Christ's birth. Two miles more will take him to the station
which will represent the age when the oldest pyramids were built. He
is still, however, in the later days of man's history on this planet.
To attain on the scale the time when man began, he might well have to
walk fifty miles away, while a journey which would thus by successive
steps describe the years of the earth's history since life appeared
upon its surface would probably require him to circle the earth at
least four times. We may accept it as impossible for any one to deal
with such vast durations save with figures which are never really
comprehended. It is well, however, to enlarge our view as to the age
of the earth by such efforts as have just been indicated.
When we go beyond the earth into the realm of the stars all efforts
toward understanding the ranges of space or the durations of time are
quite beyond the efforts of man. Even the distance of about two
hundred and forty thousand miles which separates us from the moon can
not be grasped by even the greater minds. No human intelligence,
however cultivated, can conceive the distance of about ninety-five
million miles which separates us from the sun. In the celestial realm
we can only deal with relations of space and time in a general and
comparative way. We can state the distances if we please in millions
of miles, or we can reckon the ampler spaces by using the interval
which separates the earth from the sun as we do a foot rule in our
ordinary work, but the depths of the starry spaces can only be sounded
by the winged imagination.
Although the student has been advised to begin his studies of Nature
on the field whereon he dwells, making that study the basis of his
most valuable communications with Nature, it is desirable that he
should at the same time gain some idea as to the range and scope of
our knowledge concerning the visible universe. As an aid toward this
end the following chapters of this book will give a very brief survey
of some of the most important truths concerning the heavens and the
earth which have rewarded the studies of scientific men. Of remoter
things, such as the bodies in the stellar spaces, the account will be
brief, for that which is known and important to the general student
can be briefly told. So, too, of the earlier ages of the earth's
history, although a vast deal is known, the greater part of the
knowledge is of interest and value mainly to geologists who cultivate
that field. That which is most striking and most important to the mass
of mankind is to be found in the existing state of our earth, the
conditions which make it a fit abode for our kind, and replete with
lessons which he may study with his own eyes without having to travel
the difficult paths of the higher sciences.
Although physiography necessarily takes some account of the things
which have been, even in the remote past, and this for the reason that
everything in this day of the world depends on the events of earlier
days, the accent of its teaching is on the immediate, visible, as we
may say, living world, which is a part of the life of all its
inhabitants.