Deposition of the material worn away from the surface of the land. The
total amount of sediment laid down must equal the amount of material
abstracted, save in so far as the soluble portions of that material are
retained in solution in the sea. But we have still much to learn as to
the conditions, and especially as to the rate, of sedimentation. Nor
does there appear to be much hope of any considerable increase to our
knowledge until the subject is taken up in earnest as one demanding and
justifying a prolonged series of well-planned and carefully executed
observations. We have yet to discover the different rates of deposit,
under the varying conditions in which it is carried on in lakes,
estuaries, and the sea. What, for instance, would be a fair average for
the rate at which the lakes of each country of Europe are now being
silted up? If this rate were ascertained, and if the amount of material
already deposited in these basins were determined, we should be in
possession of data for estimating not only the probable time when the
lakes will disappear, but also the approximate date at which they came
into existence.
But it is not merely in regard to epigene changes that further more
extended and concerted observation is needed. Even among Subterranean
movements there are some which might be watched and recorded with far
more care and continuity than have ever been attempted. The researches
of Professor George Darwin and others have shown how constant are the
tremors, minute but measureable, to which the crust of the earth is
subject.[96] Do any of these phenomena indicate displacement of the
crust, and, if so, what in the lapse of a century is their cumulative
effect on the surface of the land?
More momentous in their consequences are the disturbances which
traverse mountain-chains and find their most violent expression in
shocks of Earthquake. The effects of such shocks have been studied
and recorded in many parts of the world, but their causes are only
partially understood. Are the disturbances due to a continuation of the
same operation which at first gave birth to the mountains? Should they
be regarded as symptoms of growth or of collapse? Are they accompanied
with even the slightest amount of elevation or depression? We cannot
tell. But these questions are probably susceptible of some more or less
definite answer. It might be possible, for instance, to determine with
extreme precision the heights above a given datum of various fixed
points along such a chain as the Alps, and by a series of minutely
accurate measurements to detect any upward or downward deviation from
these heights. It is quite conceivable that throughout the whole
historical period some deviation of this kind has been going on, though
so slowly, or by such slight increments at each period of renewal, as
to escape ordinary observation. We might thus learn whether, after
an Alpine earthquake, an appreciable difference of level is anywhere
discoverable, whether the Alps as a great mountain-chain are still
growing or are now subsiding, and we might be able to ascertain the
rate of the movement. Although changes of this nature may have been
too slight during human experience to be ordinarily appreciable, their
very insignificance seems to me to supply a strong reason why they
should be sought for and carefully measured. They would not tell us,
indeed, whether a mountain-chain was called into being in one gigantic
convulsion, or was raised at wide intervals by successive uplifts, or
was slowly elevated by one prolonged and continuous movement. But they
might furnish us with suggestive information as to the rate at which
upheaval or depression of the terrestrial crust is now going on.
The vexed questions of the origin of Raised Beaches and Sunk Forests
might in like manner be elucidated by well-devised measurements. It
is astonishing upon what loose and unreliable evidence the elevation
or depression of coast-lines has often been asserted. On shores
where proofs of a recent change of level are observable it would not
be difficult to establish by accurate observation whether any such
movements are taking place now, and, if they are, to determine their
rate. The old attempts of this kind along the coasts of Scandinavia
might be resumed with far more precision and on a much more extended
scale. Methods of instrumental research have been vastly improved since
the days of Celsius and Linnæus. Mere eye-observations would not supply
sufficiently accurate results. When the datum-line has been determined
with rigorous accuracy, the minutest changes of level, such as would
be wholly inappreciable to the senses, might be detected and recorded.
If such a system of watch were maintained along coasts where there is
reason to believe that some change in the relative level of sea and
land is taking place, it would be possible to follow the progress of
the movement and to determine its rate.
But I must not dwell longer on examples of the advantages which geology
would gain from a far more general and systematic adoption of methods
of experiment and measurement in elucidation of the problems of the
science. I have referred to a few of those which have a more special
bearing on the question of geological time, but it is obvious that the
same methods might be extended into almost every branch of geological
dynamics. While we gladly and gratefully recognise the large amount of
admirable work that has already been done by the adoption of these
practical methods, from the time of Hall, the founder of experimental
geology, down to our own day, we cannot but feel that our very
appreciation of the gain which the science has thus derived increases
the desire to see the practice still further multiplied and extended. I
am confident that it is in this direction more than in any other that
the next great advances of geology are to be anticipated.
While much may be done by individual students, it is less to
their single efforts than to the combined investigations of many
fellow-workers that I look most hopefully for the accumulation of data
towards the determination of the present rate of geological changes. I
would, therefore, commend this subject to the geologists of this and
other countries as one in which individual, national, and international
co-operation might well be enlisted. We already possess an institution
which seems well adapted to undertake and control an enterprise of the
kind suggested. The International Geological Congress, which brings
together our associates from all parts of the globe, would confer
a lasting benefit on the science if it could organise a system of
combined observation in any single one of the departments of inquiry
which I have indicated or in any other which might be selected. We
need not at first be too ambitious. The simplest, easiest, and least
costly series of observations might be chosen for a beginning. The
work might be distributed among the different countries represented
in the Congress. Each nation would be entirely free in its selection
of subjects for investigation, and would have the stimulus of
co-operation with other nations in its work. The Congress will hold its
triennial gathering next year in Paris, and if such an organisation of
research as I have suggested could then be inaugurated a great impetus
would thereby be given to geological research, and France, again become
the birthplace of another scientific movement, would acquire a fresh
claim to the admiration and gratitude of geologists in every part of
the globe.[97]
FOOTNOTES:
[71] Presidential Address to the Geological Section of the British
Association for the Advancement of Science at the Dover Meeting 1899.
[72] _Theory of the Earth_, vol. i. p. 108.
[73] _Op. cit._, vol. i. p. 173, _note_.
[74] _Op. cit._, vol. ii. p. 329.
[75] _Op. cit._, vol. i. p. 200.
[76] _Theory of the Earth_, vol. ii. p. 205.
[77] _Op. cit._, vol. i. p. 44.
[78] _Illustrations of the Huttonian Theory_, § 118.
[79] _Trans. Roy. Soc. Edin._, vol. xxiii. (1862).
[80] _Proc. Roy. Soc. Edin._, vol. v. p. 512 (Dec. 18, 1865).
[81] _Trans. Geol. Soc. Glasgow_, vol. iii. (February, 1868), pp. 1, 16.
[82] 'The Age of the Earth,' being the Annual Address to the Victoria
Institute, June 2, 1897. _Phil. Mag._, January, 1899, p. 66.
[83] _Recent Advances in Physical Science_, p. 174.
[84] Presidential Address. _Quart. Journ. Geol. Soc._, 1869.
[85] _Trans. Geol. Soc. Glasgow_, vol. iii. (March 26, 1868), p. 189.
Sir W. Thomson acknowledged my adhesion in his reply to Huxley's
criticism. _Op. cit._, p. 221.
[86] Darwin's _Life and Letters_, vol. iii. pp. 115, 146.
[87] _Rep. Brit. Assoc._, 1886, p. 517.
[88] _Nature_, vol. li. p. 585, April 18, 1895.
[89] _Rep. Brit. Assoc._, 1886, p. 518.
[90] October 1904. Since this Address was given the subject of
radio-activity has assumed high importance in reference to questions
connected with the evolution of the cosmos. Thus Prof. George Darwin,
in view of the newly discovered properties of radium, has stated that
he sees 'no reason for doubting the possibility of augmenting the
estimates of solar heat, as derived from the theory of gravitation,
by some such factor as ten or twenty' (_Nature_, 24th Sept., 1903).
The same opinion is shared by Prof. Joly, who points out that the
establishment of the observed gradient of temperature from the
earth's surface inward 'may have been deferred indefinitely during
the exhaustion of stores of radium and similar bodies at greater or
shallower depths' (_Nature_, 1st Oct., 1903). More recently Prof.
Rutherford, who has taken so leading a part in the discussion of
radio-activity, has made the following statement: 'I think we may
conclude that the present rate of loss of heat of the earth might have
continued unchanged for long periods of time in consequence of the
supply of heat from radio-active matter in the earth. It thus seems
probable that the earth may have remained for very long intervals of
time at a temperature not very different from that observed to-day,
and that in consequence the time during which the earth has been at a
temperature capable of supporting the presence of animal and vegetable
life may be very much longer than the estimate made by Lord Kelvin
from other data' (_Radio-activity_, Cambridge, 1904, p. 346). Thus two
of the three physical arguments are impugned on new grounds, and the
forecast of Prof. Darwin is shown to have been reasonable when in 1886
he said: 'Although speculations as to the future course of science
are usually of little avail, yet it seems as likely that meteorology
and geology will pass the word of command to cosmical physics as the
converse.'
[91] _The Age of the Earth_, Presidential Address to the Victoria
Institute for 1897, p. 10; also in _Phil. Mag._, January 1899.
[92] The geological arguments are briefly given in my Presidential
Address to the British Association at the Edinburgh Meeting of 1892
(_ante_ p. 182). The biological arguments were well stated, and in some
detail, by Professor Poulton in his Address to the Zoological Section
of the Association at the Liverpool Meeting of 1896.
[93] See an interesting and suggestive paper by Professor Le Conte on
'Critical Periods in the History of the Earth,' _Bull. Dept. Geology,
University of California_, vol. i. (1895), p. 313; also one by
Professor Chamberlin on 'The Ulterior Basis of Time-divisions and the
Classification of Geological History,' _Journal of Geology_, vol. vi.
(1898), p. 449.
[94] The first Report of this Committee was submitted to the Southport
meeting of the Association in 1903. But the question is one of such
importance in view of the rapidity with which some parts of our coast
are in course of demolition that it deserves to be taken up as a
national investigation. The country at large should contribute to the
expense of applying the best means for arresting the waste of its
shores. At present the contest has to be carried on by the riparian
proprietors, who are often quite unable adequately to cope with it.
_October_, 1904.
[95] _Proc. Roy. Soc. Edin._, vol. x. (1879-80) p. 518.
[96] _Report Brit. Assoc._, 1882, p. 95.
[97] The hope here expressed has so far been realised by the
appointment of a Committee of the Geological Congress at Paris in
1900 and the renewal and extension of this Committee at the following
Meeting held in Vienna in 1903. The subjects of Earthquakes, Movements
of elevation or depression in mountain chains and measurements of
the value of Gravity were especially proposed for investigation. The
recommendations of the Committee were approved by the International
Association of Academies in London in the summer of 1904 and steps were
then taken in the direction of international co-operation in each of
the subjects suggested. _Note added_, October, 1904.
VII
The Life and Letters of Charles Darwin[98]
By the universal consent of mankind, the name of Charles Darwin was
placed, even during his lifetime, among those of the few great leaders
who stand forth for all time as the creative spirits that have founded
and legislated for the realm of Science. It is too soon to estimate
with precision the full value and effect of his work. The din of
controversy that rose around him has hardly yet died down, and the
influence of the doctrines he propounded is extending into so many
remote departments of human inquiry, that a generation or two may
require to pass away before his true place in the history of thought
can be definitely fixed. But the judgment of his contemporaries as to
his proud pre-eminence is not likely ever to be called in question. He
is enrolled among the _Dii Majorum Gentium_, and there he will remain
to the end of the ages. When he was laid beside the illustrious dead
in Westminster Abbey, there arose far and wide a lamentation as of
personal bereavement. Thousands of mourners who knew only his writings,
and judged of the gentleness and courtesy of his nature from these
and from such hearsay reports as passed outwards from the privacy of
his country home, grieved as for the loss of a dear friend. It is
remarkable that probably no scientific man of his day was personally
less familiar to the mass of his fellow-countrymen. He seemed to shun
all the usual modes of contact with them. His weak health, domestic
habits, and absorbing work kept him in the seclusion of his own
quiet household. In later years his face was seldom to be seen at
the meetings of scientific societies, or at those gatherings where
the discoveries of science are expounded to more popular audiences.
He shrank from public controversy, although no man was ever more
vigorously attacked and more completely misrepresented. Nevertheless,
when he died, the affectionate regret that followed him to the grave
came not alone from his own personal friends, but from thousands of
sympathetic mourners in all parts of the world, who had never known or
seen him. Men had ample material for judging of his work, and in the
end had given their judgment with general acclaim. Of the man himself,
however, they could know but little, yet enough of his character
shone forth in his work to indicate its tenderness and goodness. Men
instinctively felt him to be in every way one of the great ones of
the earth, whose removal from the living world leaves mankind poorer
in moral worth as well as in intellect. So widespread has been this
conviction, that the story of his life has been eagerly longed for.
It might contain no eventful incidents, but it would reveal the man
as he was, and show the method of his working and the secret of his
greatness.
At last, five years and a half after his death, the long expected
Memoir has made its appearance. The task of preparing it was undertaken
by his son, Mr. Francis Darwin, who, having for the last eight years
of his father's life acted as his assistant, was specially qualified
to put the world in possession of a true picture of the inner life
of the great naturalist. Most biographies are too long, but, in the
present case, the three goodly volumes will be found to contain not
a page too much. The narrative is absorbingly interesting from first
to last. The editor, with excellent judgment, allows Darwin himself,
as far as possible, to tell his own story in a series of delightful
letters, which bring us into the very presence of the earnest student
and enthusiastic explorer of Nature.
Charles Darwin came of a family which from the beginning of the
sixteenth century had been settled on the northern borders of
Lincolnshire. Several of his ancestors had been men of literary taste
and scientific culture, the most noted of them being his grandfather,
Erasmus Darwin, the poet and philosopher. His father was a medical man
in large practice at Shrewsbury, and his mother, a daughter of Josiah
Wedgewood of Etruria. Some interesting reminiscences are given of the
father, who must have been a man of uncommon strength of character. He
left a large fortune, and thus provided for the career which his son
was destined to fulfil. Of his own early life and later years, Darwin
has left a slight but most interesting sketch in an autobiographical
fragment, written late in life for his children, and without any idea
of its ever being published. From this outline we learn that he was
born at Shrewsbury on the 12th of February, 1809. Shortly before his
mother's death, in 1817, he was sent, when eight years old, to a
day-school in his native town. But even in the period of childhood
he had chosen the favourite occupation of his life; 'my taste for
natural history,' he says, 'and more especially for collecting, was
well developed. I tried to make out the names of plants, and collected
all sorts of things--shells, seals, franks, coins and minerals. The
passion for collecting which leads a man to be a systematic naturalist,
a virtuoso, or a miser, was very strong in me, and was clearly innate,
as none of my sisters or brother ever had this taste.' According to
his own account, he was 'in many ways a naughty boy.' But there must
have been so much fun and kind-heartedness in his transgressions, that
neither parents nor teachers could have been very seriously offended
by his pranks. What, for instance, could be said to a boy who would
gravely pretend to a schoolfellow that he could produce variously
tinted flowers by watering them with coloured fluids, or who gathered
a quantity of fruit from his father's trees, hid it in the shrubbery,
and then ran off to announce his discovery of a robbery; or who, after
beating a puppy, felt such remorse that the memory of the act lay
heavy on his conscience and remained with him to old age? In 1818 he
was placed under Dr. Butler in Shrewsbury School, where he continued
to stay for seven years until 1825, when he was sixteen years old. He
confesses that the classical training at that seminary was useless to
him, and that the school as a means of education was, so far as he was
concerned, simply a blank. Verse-making, and learning by heart so many
lines of Latin or Greek, seem to have been the occupations of school
that specially dwelt in his memory, the sole pleasure he could recall
being the reading of some of Horace's Odes. He describes, however,
the intense satisfaction with which he followed the clear geometrical
proofs of Euclid, and the pleasure he took in sitting for hours in an
old window of the school reading Shakespeare. He made acquaintance,
too, with the poems of Thomson, Byron and Scott, but confesses that in
later life, to his great regret, he lost all pleasure from poetry of
any kind, even from Shakespeare.
The first book that excited in him a wish to travel was a copy of the
_Wonders of the World_ in the possession of a schoolfellow, which
he read with some critical discrimination, for he used to dispute
with other boys about the veracity of its statements. Nothing in the
school-life could daunt his ardour in the pursuit of natural history.
He continued to be a collector, and began to show himself an attentive
observer of insects and birds. White's _Selborne_, which has started
so many naturalists on their career, stimulated his zeal, and he
became so fond of birds as to wonder in his mind why every gentleman
did not become an ornithologist. Nor were his interests confined to
the biological departments of Nature. With his brother, who had made
a laboratory in the garden tool-house, he worked hard at chemistry,
and learned for the first time the meaning of experimental research.
These extra-scholastic pursuits, which he declares to have been the
best part of his education at school, came somehow to be talked of by
his companions, who consequently nicknamed him 'Gas'; and Dr. Butler,
when he heard of them, rebuked the young philosopher, for 'wasting
time on such useless subjects,' and called him a 'poco curante.' It
was evident to his father that further attendance at Shrewsbury School
would not advance young Darwin's education, and he was accordingly sent
in 1825, when he was a little over sixteen years old, to join his elder
brother, who was attending the medical classes of the University of
Edinburgh. It was intended that he should begin the study of medicine,
and qualify himself for that profession; but he had already discovered
that a sufficient competence would eventually come to him to enable him
to live in some comfort and independence. So he went to the lectures
with no very strong determination to get from them as much good as
if he knew that his living was to depend on his success. He found
them 'intolerably dull,' and records in maturer years his deliberate
conviction that 'there are no advantages, and many disadvantages, in
lectures compared with reading.' That he did not conquer his repugnance
to the study of anatomy in particular is remarkable, when we consider
how strong already was his love of biology, and how wholly it dominated
his later life. Tenderness of nature seems to have had much to do with
his repugnance. He could not bear the sight of suffering; the cases in
the clinical wards in the Infirmary distressed him, and after bringing
himself to attend for the first time the operating theatre, he rushed
away before the operations were completed and never went back. But he
afterwards came to regard as one of the greatest evils of his life
that he had not been urged to conquer his disgust and make himself
practically familiar with the details of human anatomy. It is curious,
too, to learn with what aversion he regarded the instructions of the
Professor of Natural History in the University. Jameson could certainly
kindle, or at least stimulate, enthusiasm in some young souls, as the
brilliant band of naturalists trained under him in Edward Forbes' time
sufficiently proved. But to others he undoubtedly was, what Darwin
describes him, 'incredibly dull.' If the professorial teaching was
defective, however, the loss seems to have been in good measure made
up by the companionship of fellow-students of kindred tastes, with
whom the future naturalist explored the neighbourhood of Edinburgh.
Collecting animals from the tidal pools of the estuary of the Forth,
and accompanying the Newhaven fishermen in their dredging voyages for
oysters, he found plenty of material for study, and employed himself in
dissecting as well as he could. In the course of these observations he
made his first recorded discovery, which was 'that the so-called ova of
_Flustra_ had the power of independent movement by means of cilia, and
were, in fact, larvae.' As a part of his love of Nature and out-of-door
employments, he became an ardent sportsman, rose even long before day,
in order to reach the ground betimes, and went to bed with his shooting
boots placed open close beside him, that not a moment might be lost in
getting into them.