scientific education you were doubtless profoundly impressed by the
multiplicity of detail which met your eye in every department of
natural knowledge. When you entered upon the study of one of these
departments, you felt, perhaps, almost overpowered and bewildered
by the vast mass of facts with which you had to make acquaintance.
And yet as your training advanced, you gradually came to see that
the infinite variety of phenomena could all be marshalled, according
to definite laws, into groups and series. You were led to look
beyond the details to the great principles that underlie them and
bind them into a harmonious and organic whole. With the help of a
guiding system of classification, you were able to see the connection
between the separate facts, to arrange them according to their
mutual relations, and thus to ascend to the great general laws under
which the material world has been constructed. With all attainable
thoroughness in the mastery of detail, you have been taught to combine
a breadth of treatment which enables you to find and keep a leading
clue even through the midst of what might seem a tangled web of
confusion. There are some men who cannot see the wood for the trees,
and who consequently can never attain great success in scientific
investigation. Let it be your aim to master fully the details of the
tree, and yet to maintain such a breadth of vision as will enable you
to embrace the whole forest within your ken. I need not enlarge on the
practical value of this mental habit in every-day life, nor point out
the excellent manner in which a scientific education tends to develop
it.
In the fourth place, I would inculcate the habit of wide Reading
in scientific literature. Although the progress of science is now
too rapid for any man to keep pace with the advance of all its
departments, you should try to hold yourselves in touch with at least
the main results arrived at in other branches than your own; while,
in that branch itself, it should be your constant aim to watch every
onward step that is taken by others, and not to fall behind the van.
This task you will find to be no light one. Even were it confined to a
survey of the march of science in your own country, it would be arduous
enough to engage much of your time. But science belongs to no country,
and continues its onward advance all over the globe. If you would
keep yourselves informed regarding this progress in other countries,
as you are bound to do if you would not willingly be left behind, you
will need to follow the scientific literature of those countries.
You must be able to read at least French and German. You will find
in these languages a vast amount of scientific work relating to your
own department, and to this accumulated pile of published material
the journals of every month continue to add. In many ways it is a
misfortune that the literature of science increases so fast; but we
must take the evil with the good. Practice will eventually enable you
to form a shrewd judgment as to which authors or papers you may skip
without serious danger of losing any valuable fact or useful suggestion.
In the fifth place, let me plead for the virtue of Patience. In a
scientific career we encounter two dangers, for the avoidance of
which patience is our best support and guide. When life is young and
enthusiasm is boundless; when from the details which we may have
laboriously gathered together we seem to catch sight of some new fact
or principle, some addition of more or less importance to the sum
of human knowledge, there may come upon us the eager desire to make
our discovery known. We may long to be allowed to add our own little
stone to the growing temple of science. We may think of the pride with
which we should see our names enrolled among those of the illustrious
builders by whom this temple has been slowly reared since the infancy
of mankind. So we commit our observations to writing, and send them for
publication. Eventually we obtain the deep gratification of appearing
in print among well-known authors in science. Far be it from me to
condemn this natural desire for publicity. But, as your experience
grows, you will probably come to agree with me that if the desire
were more frequently and energetically curbed, scientific literature
would gain much thereby. There is amongst us far too much hurry in
publication. We are so afraid lest our observations or deductions
should be forestalled--so anxious not to lose our claim to priority,
that we rush before the world, often with a half-finished performance,
which must be corrected, supplemented, or cancelled by some later
communication. It is this feverish haste which is largely answerable
for the mass of jejune, ill-digested, and erroneous matter that cumbers
the pages of modern scientific journals. Here it is that you specially
need patience. Before you venture to publish anything, take the utmost
pains to satisfy yourselves that it is true, that it is new, and that
it is worth putting into print. And be assured that this reticence,
while it is a kindness to the literature of science, will most
certainly bring with it its own reward to yourselves. It will increase
your confidence, and make your ultimate contributions more exact in
their facts as well as more accurate and convincing in their argument.
The other danger to which I referred as demanding patience is of
an opposite kind. As we advance in our career, and the facts of
our investigations accumulate around us, there will come times of
depression when we seem lost in a labyrinth of detail out of which
no path appears to be discoverable. We have, perhaps, groped our way
through this maze, following now one clue, now another, that seemed
to promise some outlet to the light. But the darkness has only closed
around us the deeper, and we feel inclined to abandon the research
as one in which success is, for us at least, unattainable. When this
blankness of despair shall come upon you, take courage under it, by
remembering that a patient study of any department of nature is never
labour thrown away. Every accurate observation you have made, every
new fact you have established, is a gain to science. You may not for a
time see the meaning of these observations, nor the connection of these
facts. But their meaning and connection are sure in the end to be made
out. You have gone through the labour necessary for the ascertainment
of truth, and if you patiently and watchfully bide your time, the
discovery of the truth itself may reward your endurance and your toil.
It is by failures as well as by successes that the true ideal of the
man of science is reached. The task allotted to him in life is one
of the noblest that can be undertaken. It is his to penetrate into
the secrets of Nature, to push back the circumference of darkness
that surrounds us, to disclose ever more and more of the limitless
beauty, harmonious order and imperious law that extend throughout the
universe. And while he thus enlarges our knowledge, he shows us also
how Nature may be made to minister in an ever-augmenting multiplicity
of ways to the service of humanity. It is to him and his conquests that
the material progress of our race is mainly due. If he were content
merely to look back over the realms which he has subdued, he might well
indulge in jubilant feelings, for his peaceful victories have done more
for the enlightenment and progress of mankind than were ever achieved
by the triumphs of war. But his eye is turned rather to the future than
to the past. In front of him rises the wall of darkness that shrouds
from him the still unknown. What he has painfully accomplished seems to
him but little in comparison with the infinite possibilities that lie
beyond. And so he presses onward, not self-satisfied and exultant, but
rather humbled and reverential, yet full of hope and courage for the
work of further conquest that lies before him.
Such is the task in which you may be called to share. When you
have entered upon it and have learnt something of its trials and
responsibilities, as well as of its joys and rewards, you will look
back with gratitude to the training you received within the walls
of this College. You will feel even more keenly than you do now how
much you owe to the patient kindness and educational skill of your
teachers and to the healthy stimulus of contact and competition with
your class-fellows. Most heartily do I wish you success in your several
careers. Following up the paths which have been opened for you here,
may it be yours to enlarge still further the circle of light which
science has gained, and to wrest from Nature new aids for the service
of mankind.
FOOTNOTE:
[102] An address to the students of Mason University College,
Birmingham, at the opening of the session, on Tuesday, 4th October,
1898.
X
The Roman Campagna[103]
Among the capitals of Europe Rome has long had the unique distinction
of standing in the midst of a wide solitude. Other cities in their
outward growth have incorporated village after village and hamlet after
hamlet. As their streets and squares merge insensibly into a succession
of villas and gardens, cottages and hedgerows, followed by the farms
and fields of the open country, so the noise and stir of causeway and
pavement gradually give way to the quieter sounds of rural life. But
with the Eternal City this normal arrangement does not hold good. For
sixteen centuries she has kept herself within her ancient walls which
still surround her with their picturesque continuity of rampart and
tower. Inside these barriers we still encounter, by day and by night,
the 'fumum et opes, strepitumque Romæ.' But outside the gates we find
ourselves on a lonely prairie that sweeps in endless grassy, almost
treeless, undulations up to the base of the, distant hills. The main
roads, indeed, that radiate from the city, are bordered on either side,
for the first mile or two, with a strip of suburban _osterie_, booths
and shops, varied here and there, perhaps, by a villa and its grounds.
But these fringes of habitation are too narrow and short, and cling too
closely to their respective arteries of traffic, seriously to affect
the solitariness which broods over the intervening landscape up to the
very foot of the walls.
This surrounding district, known as the Roman Campagna, possesses
a singular fascination, which has been often and enthusiastically
described. The endless and exquisite variety of form and colour
presented by the plain and its boundary of distant mountains, together
with the changing effects of weather and season on such a groundwork,
would of themselves furnish ample subjects for admiration. But the
influence of this natural beauty is vastly enhanced by the strange and
solemn loneliness of a scene which living man seems to have almost
utterly forsaken, leaving behind him only memories of a storied past
which are awakened at every turn by roofless walls of long-abandoned
farm-buildings, mouldering ruins of medieval towers, fragments of
imperial aqueducts, decayed substructures of ancient villas and the
grass-grown sites of ancient cities whose names are forever linked
with the early struggles of Rome. European travel offers few more
instructive experiences than may be gained by wandering at will over
that rolling sward, carpeted with spring-flowers, but silent save for
the song of the larks overhead and the rustle of the breeze among the
weeds below; when the mountainous wall of the Sabine chain from Soracte
round to the Alban Hills gleams under the soft Italian sky with the
iridescence of an opal, and when the imagination, attuned to the human
associations of the landscape, recalls with eager interest, some of
the incidents in the marvellous succession of historical events that
have been transacted here. If, besides being keenly alive to all the
ordinary sources of attraction, the visitor can look below the surface,
he may gain a vast increase to his interest in the ground by finding
there intelligible memorials of prehistoric scenes, and learning from
them by what slow steps the platform was framed on which Rome rose
and flourished and fell. He will thus discover that, as befitted the
city which was to rule the world, its birthplace was fashioned by
the co-operation of the grandest forces in Nature; that, on the one
hand, subterranean upheaval and stupendous volcanic activity combined
to build up the plain and hills of the Campagna, and that on the
other, the universal and ceaseless working of the subaërial agencies
has carved it into that varied topography which is typified in the
isolation of the Seven Hills of Rome and of the many crags and ridges
that served as sites for the towns of Latium and Etruria.
Seen from the crest of the Vatican ridge, the Roman Campagna stretches
as a plain from the base of the steep front of the Apennines to the
coast of the Mediterranean--a distance of some thirty English miles.
To the north it is bounded by the ridge of Soracte and the nearer
heights of Bracciano and Tolfa. To the south it runs up to the base
of the Alban Hills and sweeps between them and the sea onwards till
it merges into the flat and pestilential Maremma. Even from such a
commanding point of view, however, this apparent plain can be seen to
be far from having an even surface. Not only does it slope upward
and inland from the coast, until, where it abuts against the foot of
the hills, it has reached heights of 600 or 800 feet, but when looked
at more closely it presents a somewhat diversified topography. Though
the heights and hollows never vary much from the general average
level, they include not only smooth, grassy ridges but also low cliffs
that run along the declivities, rising sometimes into craggy scarps;
likewise narrow gullies and ravines with steep walls, as well as wide,
open, smooth-sided valleys. The surface is for the most part clothed
with pasture; yet the brown and yellow rock that forms most of the
plain protrudes in many places, not only where it has been laid bare by
natural causes, but where it has been artificially cut away or scooped
into subterranean recesses.
Such a varied form of ground was eminently favourable for human
settlement. The earliest races could find or make rock-shelters almost
anywhere. The fertility of the soil afforded to their successors good
pasturage and fields for tillage, while the hillocks, girt round with
cliffs, and the flat-topped ridges, shelving precipitously to lower
ground, offered excellent sites for fortification and defence. Owing
to the porous nature of the ground, much of the rain sinks at once
beneath the surface, instead of flowing off in brooks. Hence many of
the valleys are usually dry, unless in wet seasons. But water can
be obtained all over the district by sinking wells, and that this
source of supply has been in use from a remote period and to an almost
incredible extent, has been strikingly shown by the recent excavations
beneath the pavements of the Roman Forum. It would be difficult to
find anywhere a form of ground which shows better the influence of
geological structure upon the early fortunes of a people.
With some portion of what has been written by Italian and other
observers on this district, I have made myself acquainted, and
having had the advantage of tracing on the ground the records of the
successive stages through which the Campagna has come to be what it is,
I propose in the following pages to give an outline of this prehistoric
chronicle. I should like to attempt to present to the reader such a
picture of the whole sequence of events as has vividly impressed itself
on my own mind, avoiding, as far as may be practicable, technicalities
and details. Three distinct successive phases can be recognised in this
sequence. First came a time when the waves of the Mediterranean broke
against the base of the steep front of the Apennines, and when all the
low grounds around Rome, and for leagues to the north and south, lay
sunk many fathoms deep. Next followed the chief period in the building
up of the Campagna. A host of volcanoes rose along the sea-floor on the
west side of Central Italy, when ashes, dust and stones were thrown
out in such quantity and for so prolonged a time as to strew over the
sea-bottom a mass of material several hundred feet thick. Partly from
this accumulation and partly by an upheaval of the whole region of
Italy, the sea-bottom with its volcanic cones was raised up as a strip
of low land bordering the high grounds of the interior, and a few huge
volcanoes were subsequently piled up to a height of several thousand
feet. Lastly succeeded the epoch in which the volcanic platform, no
longer increased by fresh eruptions, was carved by subaërial agencies
into the topography which it presents to-day. Each of these three
phases has had its history legibly graven in the rocky framework of the
Campagna, and some of its memorials may be recognised even within the
walls of Rome.
I. The records of the first period lie beneath the Seven Hills on the
left bank of the Tiber, but rise high above the plain on the right
bank, where they form the chain of heights that culminates in Monte
Mario, 455 feet above the level of the Mediterranean. These records,
forming the series known to geologists by the name of Pliocene, consist
of a lower bluish-grey clay and an upper group of yellow sands and
gravels, the whole being probably a good deal more than 450 feet thick.
The clay (Plaisancian) has been found to extend, with a remarkable
persistence of aspect and contents, from the north to the south of
Italy. It has yielded several hundred species of mollusks and other
organisms, which show it to be a thoroughly marine silt, deposited on
the bottom of a sea of some little depth.
At the time of the deposition of this clay the mountainous backbone of
the country had already undergone the greater part of that prolonged
series of terrestrial disturbances whereby solid sheets of limestone
were folded, crushed, ruptured and driven together into a series of
parallel ridges, having a general trend from northwest to southeast,
and forming the nucleus of what is now the chain of the Apennines.
At the epoch when our story begins, however, this chain was still
incomplete, and probably a good deal lower, as well as narrower, than
subsequent upheaval has made it. Instead of forming, as it now does,
the lofty axis of a broad peninsula, it then consisted of a series of
parallel islands and islets, separated from each other by long and
often narrow sounds or channels. In general appearance it must have
resembled parts of the coast of Dalmatia on the opposite side of the
Adriatic. Many of the more prominent mountains of the region stood then
entirely surrounded by the sea. The Sabine Hills, for example, rose as
an island, while Soracte formed another island farther west. A long
strait ran northwards by Rocca Sinibalda and Rieti to Terni; another of
narrower width stretched towards Perugia and formed then the estuary
of the Tiber. All the Roman Campagna, together with the low grounds
on both sides of the Apennines, was at that time submerged under the
sea. The great band of volcanic heights and cones that extends from
Aquapendente to the Bay of Naples had not yet come into existence, but
over their site the waters of the Mediterranean lay many fathoms deep.
The climate of Europe had for ages been of so genial a character that
sub-tropical types of life had long flourished both in the sea and on
the land of this quarter of the globe. But in the period of geological
history with which we are now concerned, a remarkable diminution of
temperature was in progress all over the Northern hemisphere. As
the warmth grew less, the distribution of plants and animals came
to be seriously affected. Many southern forms were extirpated from
districts which they had long inhabited, while in their place came
migrations of northern species. This modification made itself felt
both on terrestrial and marine life. Thus in the Atlantic Ocean a
number of northern shells, which had pushed their way southward even
as far as the coasts of the Spanish peninsula, were able to enter
the Mediterranean when a connection was opened between that inland
sea and the main ocean outside. It is interesting to note that among
the shells introduced into the Mediterranean basin at this time were
_Astarte borealis_, _Buccinum groenlandicum_, _Cyprina islandica_,
_Panopaea norvegica_ and others whose appellations sufficiently
indicate the latitudes where they now find their chief home. On the
land, too, such quadrupeds as the reindeer and the now extinct mammoth
wandered from the plains of Lapland and Russia to the shores of Italy.
Eventually when the refrigeration gave way to the return of more
genial conditions, the northern invaders died out. They have no living
descendants now in the south of Europe.
The grey clay which forms the lower division of the Roman Pliocene
series is best seen on the right side of the Tiber where it forms the
lower half of the ridge of the Vatican and Monte Mario, and where
for more than five-and-twenty centuries it has supplied material
for making the bricks of which ancient and modern Rome has been so
largely constructed. The same clay has been found at lower levels on
the opposite side of the river. On the flanks of the Pincian Hill,
at the Piazza di Spagna, it was exposed about twelve years ago in
some excavations connected with the adjustment of the aqueduct of
the Aqua Vergine. Only a few feet below the crowded pavements of that
busy thoroughfare lies the old sea-bottom with its abundant relics of
marine life. In borings for water which have been made around Rome the
same deposit has been ascertained to extend below the later volcanic
formations of the Campagna. Thus at the Appia Antica fort, near the
tomb of Cecilia Metella, the clay was entered at a depth of about 300
feet from the surface or eighty feet below the level of the sea. As
the upper limit of the clay at Monte Mario lies about 200 feet above
sea level and the distance from that outcrop to the fort in question
is about six miles, it might be inferred that there is here evidence
of a southeasterly dip of the deposit amounting to forty-six feet in
a mile. But before any inference of this kind can be accepted, some
considerations should be taken into account, of the highest interest
and importance in relation to the early history both of the Campagna
and of the Apennine chain.
Before dealing with these questions, however, let us complete the
examination of the marine deposits of Monte Mario. In the valuable
section disclosed on the slopes of that hill, the grey clay is seen
to become sandy towards the top and to include seams of sand which
rapidly increase in thickness, until, with their included layers of
gravel, they form nearly the whole of the upper part of the ridge.
These yellow sands, generally distinguished by the name of 'Astian,'
have been traced, like the clay below them, along nearly the whole
length of the Italian peninsula. The striking contrast which, in the
nature of their material, they present to the clay, plainly points to
a great alteration of the geography of the coasts at the time when
they were deposited. The sea must have become rapidly shallower. Not
improbably one of the uplifts now took place, whereby the land has been
raised at intervals to its present height. The steepness of the descent
of the mountains into the sea might not lead at once to much gain of
land along the western coast; but instead of the grey mud that had
previously accumulated in the deeper water, coarser sediment, brought
down by numerous torrents from the hills, now spread out over the
sea-bottom. Such a transition from the finest silt to gravel and sand
could not fail to affect the distribution of the animals living along
the coast-line. Accordingly, on comparing the fossils in the sands with
those of the clay, we see that while some of the shells, especially
the larger and more massive kinds, continued to flourish in abundance;
others, which found their most congenial haunts in tranquil waters,
were driven further out to sea.