revolutions, and hence coal-fields are often called coal-basins. Thus,
in the coal-field south of Malmesbury, the strata appear to dip from the
surface, and rise again to it after attaining a certain depth, so that a
section of them suggests the idea of a boat or basin.
Very commonly one portion of a continuous stratum or series of strata
has been broken away from the rest, and has been displaced, either by
elevation or depression, or shifting on one side, for various distances.
The amount of displacement is sometimes only a few inches, and at other
times several hundred fathoms, and the extent may be twenty yards or
twenty miles.
We may easily conceive the difficulties which these disruptions
frequently throw in the way of the miner, who in following what he
considers a valuable seam of coal is suddenly stopped by coming in
contact with a fault, a trouble, or a slip, as these phenomena are
expressively called, and finds the coal shifted several yards above or
below, or even completely lost. On the other hand, the miner, thus
provokingly stopped in his labours, must not forget that it is perhaps
owing to the very shifts he complains of that the outcrop of the coal
has occurred at all in his neighbourhood, and that the coal is workable
throughout a very large portion of the district in which he is
interested.
A most important advantage is also derived from the existence of these
numerous faults in coal strata; namely, that they intersect a large
field of coal in all directions, and by the clayey contents which fill
up the cracks accompanying minor faults, they become natural coffer-
dams, which prevent the body of water accumulated in one part of the
field from flowing into any opening which might be made in it in another
part. A remarkable instance of the advantage arising from the presence
of a great line of fault occurred in the year 1825 at Gosforth, near
Newcastle, where a shaft was dug on the wet side of what is locally
termed the Great Ninety Fathom Dyke, which there intersects the coal-
field. The workings were immediately inundated with water, and it was
found necessary to abandon them. Another shaft, however, was sunk on the
other side of the dyke, only a few yards from the former, and in this
they descended nearly 200 fathoms, or 1,200 feet, without any hindrance
from the water.
The separation of a coal-field into small areas by dykes or faults is
likewise very beneficial in case of fire in a coal-pit, for in this case
the combustion is prevented from spreading widely, and destroying, as it
otherwise would, the whole of the ignited seam.
‘The natural disposition of coal in detached portions,’ says the author
of an excellent article in the _Edinburgh Review_,[64] ‘is not simply a
phenomenon of geology, but it also bears upon national considerations.
It is remarkable that this natural disposition is that which renders the
fuel most accessible and most easily mined. Were the coal situated at
its normal geological depth, that is, supposing the strata to be all
horizontal and undisturbed or upheaved (_sic_), it would be far below
human reach. Were it deposited continuously in one even superficial
layer, it would have been too readily, and therefore too quickly mined,
and all the superior qualities would be wrought out, and only the
inferior left; but as it now lies, it is broken up by geological
disturbances into separate portions, each defined and limited in area,
each sufficiently accessible to bring it within man’s reach and labour,
each manageable by mechanical arrangements, and each capable of gradual
excavation without being subject to sudden exhaustion. Selfish
plundering is partly prevented by natural barriers, and we are warned
against reckless waste by the comparative thinness of coal-seams, as
well as by the ever-augmenting difficulty of working them at increased
depths. By the separation of seams one from another, and by varied
intervals of waste sandstones and shales, such a measured rate of mining
is necessitated as precludes us from entirely robbing posterity of the
most valuable mineral fuel, while the fuel itself is preserved from
those extended fractures and crumblings and falls which would certainly
be the consequence of largely mining the best bituminous coal, were it
aggregated into one vast mass. In fact, by an evident exercise of
forethought and benevolence in the Great Author of all our blessings,
our invaluable fuel has been stored up for us in deposits the most
compendious, the most accessible, yet the least exhaustible, and has
been locally distributed into the most convenient situations. Our coal-
fields are, in fact, so many _bituminous banks_, in which there is
abundance for an adequate currency, but against any sudden run upon them
nature has interposed numerous checks, by locking up whole reserves of
the precious fuel in the bank cellar, under the invincible protection of
ponderous stone-beds.’
Footnote 64:
Vol. cxi. p. 80.
If we examine the nature of the mineral fuel thus provided for us in the
bowels of the earth, we find a number of varieties greatly differing
from each other in chemical composition and in combustible value. Thus
the _anthracites_ or _non-bituminous coals_, which contain from eighty-
five to ninety-seven per cent. of pure carbon, are not easily ignited,
and yield no flame and but little or no smoke.
[Illustration:
Map showing the
COAL FIELDS
and
CHIEF MINING DISTRICTS
of
GREAT BRITAIN
]
The _bituminous coals_, on the contrary, contain a large proportion of
volatile matter, amounting to as much as thirty, forty, or fifty per
cent., and are consequently very inflammable, burning with a bright
flame, considerable smoke, and a penetrating odour.
But as Nature in general does not love those sharp divisions to which
theorists are so partial, thus also there is no fixed boundary between
these two classes of mineral fuel; and we find an uninterrupted series
of intermediate qualities between pure anthracite and the fattest coal.
It may be remarked that if coal were of one uniform chemical
composition, its utility would be confined within narrower limits, as
the bituminous, semi-bituminous, and anthracital varieties have each
their distinguishing properties which adapt each to special uses. Some
kinds, from their richness in volatile bituminous matter, are excellent
for the manufacture of illuminating gas, while, from their smaller
proportion of carbon, they could hardly be used for the making of iron;
and the anthracites, which yield little or no gas, are very serviceable
for smelting or domestic purposes.
It appears from the researches of modern chemistry that the different
varieties of coal are due to the progress of decomposition which wood
and vegetable matter undergo when buried in the earth, exposed to
moisture, and partially or entirely excluded from the air. Slowly
evolving carbonic acid gas, and thus parting with a portion of their
original oxygen, they become gradually converted into lignite or wood-
coal, which contains a larger proportion of hydrogen than wood does. A
continuance of decomposition changes this lignite into common or
bituminous coal, chiefly by the discharge of carburetted hydrogen, or
the gas by which we illuminate our streets and houses; and bituminous
coal still continuing to evolve its volatile matter, not only after its
being covered with strata thousands of feet in thickness, but even to
the present day (as the fire-damp sufficiently proves) is thus
ultimately transformed into anthracite, to which the various names of
splint-coal, glance-coal, hard-coal, and culm have been given.
When we consider the manner in which coal has been formed in swampy
lowlands, or more particularly in river-deltas, which gradually subsided
to a considerable depth beneath the level of the sea, we cannot wonder
that, when compared with the whole extent of the globe, the area of the
coal-fields is extremely limited, and confined to but a few favoured
countries. In our times delta lands occupy but a small part of the
continents and large islands, and there is no reason to suppose that
they were more considerable during the carboniferous age, or at any
other epoch. Besides, many of the ancient deltas, probably, never
subsided at all, so that no coal could be formed on their site; and
others, where coal strata were gradually piled up, may still be whelmed
beneath the sea awaiting some future upheaval to become serviceable to
future generations of man.
After the preliminary remarks on coal and the coal formation in general,
I will now briefly describe the chief coal-producing countries of the
globe. First on the list stands Great Britain, whose pre-eminence in
industry and commerce is entirely founded on her vast deposits of coal.
It is this invaluable mineral which sets those countless steam-engines
in motion that perform the labours of a hundred millions of men; which
spins and weaves the cotton of America, the silk of China, the wool of
Australia, and the flax of Belgium into that amazing variety of tissues
that serve to clothe almost all the nations of the globe; and which
finally produces a greater quantity of the cheapest iron than the
combined efforts of all the world. Thus our coals may well be called our
black diamonds, and the comparison is indeed paying the latter too high
a compliment, for larger masses of diamonds would be utterly worthless,
while, by means of our coal, we are able to enjoy the produce of every
zone.
Not only do our fifty-one coal-fields surpass in magnitude those which
are disseminated over a far greater territory in Germany, Belgium, and
France; but their local distribution and geological formation are as
favourable as could possibly be wished. Furthest north we see the
considerable deposits of Scotland extending from the coast of Fife to
the valley of the Clyde. It is to them that Glasgow owes its half-a-
million of inhabitants, and a wealth far surpassing that of all Scotland
under the reign of ‘bonnie’ Queen Mary. In England, north of the Trent,
along the Wear and Tyne, and even extending far beneath the sea, we have
the coal-fields of Northumberland and Durham, with Cumberland and those
of Yorkshire, Nottinghamshire, and Derbyshire. After these comes the
large field of Lancashire, or, as it is sometimes named, the Manchester
Coal-field. Looking to the central districts, we see the coals of North
and South Staffordshire and of Leicestershire. In the north-west we have
the field of North Wales; in the more central west, the deposits of the
Plain of Shrewsbury, Coalbrook Dale, and the Clee Hills; and in the
south-west, the great coal-field of South Wales, and the minor ones of
the Forest of Dean, of Somersetshire, and of Gloucestershire.
[Illustration:
COAL BASIN OF CLACKMANNANSHIRE.
_a_, _b_. Coal seams. _c_. Limestone strata. _x_, _y_. Slips.
]
The inspection of a good geological map shows us at once how
advantageously for commerce these several coal-stores are distributed.
Every large coal-field in England and Scotland is hardly ever distant
more than thirty miles from the next, so that from the Clyde to
Somersetshire the whole interior of the country can easily, by means of
canals and railroads, be provided with fuel. The east and west coasts of
the land are nowhere above fifty miles from a coal-field; and even the
most remote localities in the three kingdoms are able to provide
themselves from distances within 150 miles.
But it is chiefly the neighbourhood of the sea which gives such an
incomparable value to our most important coal-fields; as, thanks to this
advantageous situation, which none of the French, Belgian, and German
coal-fields possess, Great Britain is enabled to provide not only her
own coast-towns, but almost all the sea-ports in the world, with a
cheaper fuel than can be produced in their own country. Even in Ostend,
Belgian coal, rendered dear by canal transport, is unable to compete
with that which is brought over sea from England; and Hamburg provides
herself with fuel from Newcastle and Hartlepool, and not from the coal-
fields of Saxony and Westphalia.
Coal is found in seventeen counties in Ireland, over an area of about
3,000 square miles. Yet, notwithstanding this great abundance of coal
which the country possesses, and which is distributed throughout almost
all parts of the island, from Limerick to Antrim, her capital and chief
cities and ports have hitherto depended upon Great Britain for their
supplies of mineral fuel, both for domestic and for manufacturing
purposes. To those who are unacquainted with the actual circumstances,
it appears scarcely credible that this fine country has made so little
use of the coal which has been so bountifully bestowed upon her. Among
other causes not political, which perpetuate this state of things, is
the extraordinary facility and cheapness with which the ports of Ireland
can be supplied from the great western coal-fields of Great Britain. The
excellence, abundance, and cheapness of peat, which is not only the
common fuel of the poor in the interior, and, indeed, of all classes in
some districts, but is also brought in barges by the great canal, and
consumed to a considerable amount in the capital itself, is another
reason why the Irish coal-mines have, as yet, been so little worked.
When we consider the vast importance of coal, we cannot wonder at the
paramount influence which it has exercised over the distribution of our
population in modern times. While Salisbury, Winchester, and Canterbury—
important towns of mediæval England—are reduced to atrophy from the
distance and absence of coal-fields, Newcastle, Leeds, Manchester,
Sheffield, Birmingham, Glasgow, and a host of other flourishing towns
may truly be said to be built on coal.
Where there are large coal-fields there is life and a prospect of almost
unlimited prosperity, for they are sure to attract machinery and man.
Take a geological map of a new and thinly-populated country; and if it
be marked with coal-fields the spots where large cities will exist
hereafter may be safely determined.
A more detailed examination of the chief coal-fields of England shows us
the immensity of the mineral riches which are here still hoarded up for
the benefit of future generations.
The superficial extent of the South Welsh coal-fields is about a
thousand square miles. On its northern wing we find on an average
twenty-one coal bands, forming an aggregate thickness of eighty and a
half feet. In some parts of the south wing there are even as many as
thirty-three bands of an aggregate thickness of one hundred and four
feet of pure coal, so that the average depth of the field may be
estimated at ninety-two feet.
Numerous transversal valleys intersect this magnificent coal-field, and
afford the easiest means of working it in every depth. They also
facilitate the transport of the coal on the canals and railroads which
lead along their bottom or along their slopes to the harbours of the
Bristol Channel. In the chapters on iron and copper, I have had occasion
to describe the gigantic industries, founded on these natural
advantages, which have raised South Wales from being one of the most
insignificant into one of the most important provinces of the empire.
All the coals of this basin are so rich in carbon as to yield from
seventy to ninety per cent. of coke. They are either anthracites or only
semi-bituminous, and are consequently not suitable for making gas, nor
are they much liked for burning in open fire-places, as they do not emit
a genial flame. On the other hand, the semi-bituminous Welsh coal is
invaluable for burning in steam-engines, for it has been proved to
generate one-quarter more steam than any other kind of English coal. One
of its properties—by no means unimportant—is its non-liability to
spontaneous combustion, which, it is well known, occasionally takes
place with bituminous coals, and by which vessels have been lost at sea,
and warehouses ignited on land. The value of the Welsh steam or slightly
bituminous coal is enhanced by its quality of burning almost without
smoke, a property hitherto slightly appreciated, but the importance of
which in time of war is evident. Steamers burning the fat, bituminous
coal can be tracked at sea at least seventy miles, before their hulls
become visible, by the dense columns of black smoke pouring out of their
pipes or chimneys, and trailing along the horizon. It is a complete
tell-tale of their whereabouts, which is not the case with vessels
burning Welsh or anthracital coal. From its compactness and density, the
latter has likewise great advantages in point of stowage space over the
ordinary weak bituminous coals. For long voyages this concentration of
power and economy of space may easily be appreciated. From its great
superiority over other kinds, Welsh coal has been exclusively used for
some time past by the French Government, and it is also employed in
England by all the chief mail packet companies.
Coal is not exported from the South Wales basin as much as from some
other fields, owing to the enormous requirements of the large iron
works, most of which consume as much as can be supplied by their
collieries. Every week, however, sees increased supplies of Welsh coal
thrown into the London market, and every year fresh collieries are
opened to meet the demand. The total number of pits in South Wales in
1865 was four hundred and eighteen, which produced between seven and
eight million tons annually. The New Navigation Pit at Mountain Ash may
be cited as an example of the grand scale on which the most important of
these workings are conducted. The shaft is eighteen feet in diameter
inside the walling, and divided into four compartments, two of which are
for the drawing of coal, one for sending the workmen up and down, and
the fourth for the drainage. Notwithstanding the great depth of three
hundred and seventy yards, a carriage containing two half-tons of coal
can be wound up in one minute, and the whole colliery is estimated to
supply more than one thousand tons a day. The mineral property extends
over an area of seven miles long by three miles in width, covering from
four thousand to five thousand acres of four-foot coal. From this one
case the reader may form a slight estimate of the boundless resources of
the whole basin.
The Great Central Coal-field, which ranges through South Yorkshire,
Nottinghamshire, and Derbyshire, has a superficial extent of about one
thousand square miles. In character it is closely allied to that of
Newcastle, and is considered by some geologists to be a re-emergence of
the same strata from beneath the covering of the magnesian limestone
under which they suppose it to be concealed through the intervening
space. It extends a little from the north-east of Leeds nearly to Derby,
a distance of more than sixty-five miles. Its greatest width—twenty-
three miles—is on the north, reaching nearly to Halifax on the west. On
the south it extends towards the east to Nottingham, and is there about
twelve miles wide. Though possessing some fine coal-seams, it is of far
inferior importance to the Manchester or South Lancashire Coal-field,
from which it is separated by a lofty chain of hills. This highly
valuable basin, which extends over about five hundred and fifty square
miles, begins in the north-west of Derbyshire, and continues thence to
the south-west part of Lancashire, forming an area somewhat in the shape
of a crescent, having Manchester nearly in the centre.
[Illustration:
DUDLEY COAL-FIELD.
1. Limestone strata. 2. Coal.
]
Of the smaller coal-fields, the most important are the Whitehaven basin
(one hundred and twenty square miles) and the Dudley or South
Staffordshire area (ninety square miles) which is particularly valuable
for the extensive iron works which it maintains. One portion of this
coal-field is distinguished by the presence of one continuous bed of
coal thirty feet thick, which for British coal is astonishing; and this
mass extends seven miles in length and four in breadth. In this favoured
district coal-seams five or six feet thick are called thin seams; in
Newcastle they would be called thick seams.
Though not so extensive as the South Welsh area, the coal-fields of
Newcastle and Durham are of far more ancient celebrity. Their produce is
chiefly shipped on the Tyne, Wear, and Tees, small rivers hardly
traceable on a map of the world, and yet far more important to commerce
than the mighty Orinoco or the thousand-armed Amazon. This magnificent
coal area is bounded on the north by the river Coquet, and extends
southward nearly as far as Hartlepool, a distance of about forty-eight
miles. Its extreme breadth is about twenty-four miles, and the whole
superficial extent may amount to about eight hundred square miles.
There are in all about fifty-seven different seams of coal in the Great
Northern Coal-field, varying in thickness from an inch to five feet five
inches and six feet, and comprising an aggregate of about seventy-six
feet of coal.
The pits are established chiefly with reference to one or more of the
three following seams. The most valuable is called the _High Main Seam_,
and is about six feet thick. The next in value is the _Bensham Seam_,
about three feet thick, which is remarkable for its excellent quality as
a domestic coal, and for the enormous quantity of gas evolved from it in
the mine. The _Hutton or Low Main Seam_, averaging from three feet six
inches to five feet nine inches, is likewise of very good quality, and
is extensively worked. It must, however, be remarked that the same seam
of coal is not generally valuable in all places. Thus the High Main,
which furnishes excellent coal on the Tyne, becomes injured as it
proceeds in a south-easterly direction by being intermixed with a band
of coal of inferior quality containing iron pyrites, &c.
The Newcastle Coal-field is generally worked at a great depth, an
expense of upwards of 50,000_l._ having in some instances been incurred
before the seam of coal was reached which was to reward all this vast
outlay and labour. The most remarkable and enterprising work of this
kind on record is a sinking at Monk Wearmouth Colliery near Sunderland.
After piercing the superincumbent beds of magnesian limestone and lower
new red sandstone, the coal strata were reached at a depth of three
hundred and thirty feet; but at the same time a spring was tapped which
poured water into the workings at the rate of three thousand gallons per
minute. This fearful influx was kept under by a steam-engine of two
hundred horse-power, and the work was made sure by strong metal tubbing,
and carried on successfully, though not without extreme difficulty. On
entering the coal measures, however, a new and unexpected check was
experienced in the extra thickness of the uppermost coal strata, for
which no calculation had been made, and the difficulties were increased
when at the depth of one thousand feet a fresh _feeder_ or spring of
water was tapped. Additional expense and great loss of time were thus
caused; but the proprietors persevered with real Anglo-Saxon
pertinacity, undaunted by the apparently hopeless nature of the
undertaking, and by the fearful expenses incurred. Success crowned their
efforts, and finally, at a depth of 1,710 feet, the Hutton seam of coal
was reached, at a cost which, including the necessary preliminary
operations, could not have been less than 100,000_l._
Another remarkable and costly piece of mining was that of Gosforth
Colliery, which lies about three miles north from Newcastle, on the west
bank of a romantic ‘dean’ or little valley, through which the Ouseburn
winds its way to the Tyne. The sinking was commenced in 1825, and the
coal was won on Saturday, January 31, 1829. The High Main coal was
reached at twenty-five fathoms below the surface, but near its first
appearance the seam was thrown down in an inclined direction by the
great Ninety Fathom Dyke which there intersects the coal-field. Hence it
became necessary to sink the shaft to the depth of 181 fathoms, in order
to come at the level of the lower range of coal. This having been
accomplished, a horizontal drift 700 yards long was worked through the
face of the dyke to the seam of coal a little above its junction with
the dyke. A great part of this excavation had to be made through solid
rock. To celebrate the completion of this remarkable work, a grand
subterranean ball was given at the very place of triumph, 1,100 feet
below the surface of the earth. As the guests arrived at the bottom of
the shaft they went to the end of the drift to the face of the coal,
where each person hewed a piece of coal as a memento of the day, and
then returned to the ball-room, which was brilliantly lit up, and where
born-and-bred ladies joined in a general dance with born-and-bred
pitmen’s daughters. Between 200 and 300 persons were present, nearly
one-half of them belonging to the fair sex. It must be remembered that
the pit had not been worked, so that no smoke and dust exuded from its
mouth or defiled the ball-room.
Some of the older coal-pits, where excavations have been going on
perhaps for a century or more, may be likened to large subterranean
cities. The galleries of St. Hilda Colliery, near South Shields, are
full seventy miles long; and Killingworth pits are said, on good
authority, to have nearly one hundred and sixty miles of gallery
excavation.
In some parts the operations of the collier have encroached upon the
domains of the ocean. At the Howgill pits, for instance, west of
Whitehaven, the excavations have been carried more than 1,000 yards
under the sea, and about 600 feet below its bottom. But the most
remarkable marine colliery which Great Britain has ever possessed was
situated at Borrowstounness. The coal was found to continue under the
bed of the sea in this place, and the colliers had the courage to work
it half a mile from the shore, where there was an entry that went down
into the submarine coal-pit. This was made into a kind of round quay,
built so as to keep out the tide which flowed there twelve feet. Here
the coals were laid, and a ship of that draught of water could lay her
side to the quay and take in the coal. This wonderful pit, which
belonged to the Earl of Kincardine’s family, continued to be wrought
many years to the great profit of the owners, and the astonishment of
all that saw it; but at last an unexpected high tide drowned the whole
at once, together with the labourers who were at work. ‘While,’ says the
French geologist, Faujas de Saint Fond (who visited this remarkable mine
about the end of the last century), ‘the pitmen, by the dismal shine of
their lamps, make the deep caverns resound with the blows of their
pickaxes, ships driven by a fair wind sail over their heads, and the
sailors, rejoicing at the beautiful weather, express their joy in songs:
at another time a storm arises; the horizon is in flames, the thunder
roars, the sea rages, the boldest tremble; then the pitmen, unconscious
of the terrible scene, calmly pursue their labours, and think with
pleasure of their homes, while the ship above is shattered to pieces and
sinks; unfortunately, but too faithful a picture of the daily changes of
human life.’
[Illustration:
Map showing the
COAL FIELDS
and
MINERAL DISTRICTS
of
AMERICA
]
Nowhere in the world, perhaps, does human activity display a more
restless energy than on the site of the Newcastle Coal-field, where,
night and day, successive trains heaped with the black diamonds of
England speed along far-stretching railways, and hurry down to river and
ocean, until they are unloaded and their contents shipped by machinery.
Steam-engines are unceasingly at work drawing coals and pumping out
water. Thousands of men are underneath our feet cutting down the coal by
severe and peculiar labour, while thousands above are receiving the
loads and speeding them forwards.
‘Go where you will, there is a network of small railways, leading from
pit to pit in hopeless intricacy, but all having a common terminus on
the river’s bank or the ocean’s shore. Go where you will, tall chimneys
rise up before you, and here and there a low line of black sheds,
flanked by chimneys of aspiring altitude, indicates that you are
arriving at a colliery. As you draw nearer, men and boys of blackest hue
pass you and peer at you with inquiring glances. Now trains of coal-
waggons rush by more frequently, noises of the most discordant character
increase, and you know that you are at the pit’s mouth, when you behold
two gigantic wooden arms slanting upwards, upon which are mounted the
pulleys and wheels that carry the huge flat wire ropes of the shaft. For
a moment the wheels do not revolve—no load is ascending or descending—
but the next minute they turn rapidly, and up comes the load of coals or
human beings to the surface. Perhaps the most impressive sight is a
large colliery fully engaged at nightwork, with burning crates of coal
suspended all around; and after this a view from some neighbouring
eminence of all the far-flaming waste coal-heaps, burning up the
accumulation of waste and small coal not worth carriage, ever added to
the ever-consuming mound, until the whole district appears like the
active crater of some enormous volcano.’[65]
Footnote 65:
‘Edinburgh Review,’ vol. cxi. p. 86.
The banks of the Tyne are in many places very high and precipitous, and
consequently render peculiar contrivances necessary for the shipping of
the coals. The means used for this purpose are various: sometimes
inclined tunnels, through which the train of waggons is lowered in
chains to the water; sometimes slopes, along which the coals are
shovelled into the ship, or still better, the ingenious mechanism of
which William Howitt gives us the following description:—
‘As you advance over the plain you see a whole train of waggons loaded
with coal, careering by themselves without horse, without steam-engine,
without man, except that there sits one behind, who, instead of
endeavouring to propel these mad waggons on their way, seems labouring
hopelessly by his weight to detain them.
‘But what is your amazement when you come in sight of the river Tyne,
and see these waggons still careering on to the very brink of the
water!—to see a railway carried from the high bank, and supported on
tall piles, horizontally, above the surface of the river, and to some
distance into it, as if to allow those vagabond trains of waggons to run
right off, and dash themselves down into the river!
[Illustration: SHIPPING COAL.]
‘There they go, all mad together! Another moment, and they will shoot
over the end of the lofty railway, and go headlong into the Tyne,
helter-skelter. But behold! these creatures are not so mad as you
imagine them. They are instinct with sense; they have a principle of
self-preservation, as well as of speed, in them. See, as they draw near
the river they pause, they stop! one by one they detach themselves; and
as one devoted waggon runs on, like a victim given up for the salvation
of the rest, to perform a wild summersault into the water below, what do
we see? It is caught! A pair of gigantic arms separate themselves from
the end of the railway. They catch the waggon, they hold it suspended in
the air, they let it softly and gently descend—and whither? Into the
water? No; we see now that a ship already lies below the end of the
railway. The waggon descends to it; a man standing there strikes a bolt,
the bottom falls, and the coals which it contains are nicely deposited
in the hold of the vessel. Up, again, soars the empty waggon in that
pair of gigantic arms. It reaches the railway; it glides like a black
swan into its native lake upon it; and away it goes, as of its own
accord, to a distance, to await its brethren, who successively perform
the same exploit, and then joining it, all scamper back again as hard as
they can over the plain to the distant pit.’
The produce of the collieries situated further up the Tyne, where the
river is no longer navigable by sea-going craft, is conveyed in a kind
of oval vessels, called keels, to the port of Newcastle, or its out-
stations, North and South Shields, where it is discharged into larger
ships.
Newcastle may well be called the capital of King Coal. Once a town of
military importance, as the old, grim-looking donjon-keep of Robert
Curthose, the son of the Conqueror, still testifies, it entirely owes
its modern importance to the treasures of coal adjacent to its walls.
Its quays, black and sooty as the mineral on which its prosperity is
founded, are lined with a dense row of counting-houses, and before them
in the river still denser rows of colliers lie at anchor; while between
both ebbs and flows a black-looking crowd—for all here wear the livery
of the article to which all owe their bread. Some idea may be formed of
the vast activity waving to and fro in this chief artery of the coal
trade, from the fact that the annual arrivals in the Tyne are not less
than 13,000 or 14,000, 10,000 of which are on account of the coal trade.
Sunderland, the great port of the river Wear, where annually more than
10,000 cargoes of coal are shipped to all ports of the world;
Hartlepool, a town of modern date with magnificent docks; Stockton-on-
Tees, and a number of minor places of shipment on the coast, likewise
owe their prosperity to coal, so that probably no other article of trade
gives constant employment to so many vessels within so confined a
territory.
From Tynemouth Priory, a ruin romantically situated on a bold
promontory, the visitor frequently enjoys a magnificent marine picture;
for when, after long-continued easterly gales, the wind changes to a
westerly breeze, many hundred vessels—mostly colliers—put to sea
together in a single tide, and distribute themselves over the ocean with
their prows turned in almost every direction, some southward and coast-
wise, for English ports, for the Channel, and for the southern countries
of Europe; others, northward for Scotland and the Norwegian coast; and
others, again, due east, for Denmark and the Baltic—all sinking deep in
the water, weighed down by that mineral fuel which is more valuable for
England than if it were replaced by the mines of Mexico or the diggings
of Australia.
Yet a few years, and probably the dingy and crawling craft, which
perform the chief part in this animated scene, will be abolished.
Clipper screw steamers are rapidly taking their place, and the railroads
daily transport a greater proportion of the seven or eight million tons
of coal which are annually devoured by our huge metropolis.
Before quitting the Northern coal districts, a few words may be added on
the swarthy population whose labours bring their subterranean riches to
the light. The chief underground workmen are the hewers, who either
remove the coal with pickaxes, or sometimes blast it with powder. To hew
well is a work of skill as well as of strength, and men must be early
practised in it to earn high wages by piece-work. In tolerably thick
seams of coal of five and six feet and upwards, hewing is more a work of
strength than skill; but in the narrower seams skill predominates. In
these the arm is confined, the blow is shortened, the pick is impeded.
To gain space by adaptation of position, you may see one hewer kneeling
down on one or both knees, another squatting, another stooping or
bending double, and occasionally one or more lying on their sides or on
their backs, picking and pegging away at the seam above them. If the
seam be hard as well as thin, and the man’s position confined, it is
manifest that he cannot get his strength to bear in full, or his full
measure of coals. In such cases he is bathed in perspiration, in a state
of semi-nudity, enveloped in floating and clinging coal-dust. If to this
we add the very faint light imparted by the Davy lamps, the constantly
thickening atmosphere, the exhalations from living beings, exaggerated
by heat, and not diminished by any free current of air, and remember
that eight hours is the usual day’s work of the hewer, we must surely
confess that few men have their strength more hardly tasked, or earn
their bread in a more laborious manner.
[Illustration: COAL HEWERS AT WORK.]
To relieve this arduous toil, coal-cutting machines have lately been
devised, which are worked either by steam or by compressed air, and will
probably in time perform a great part of the hewer’s labour, as those
already in employment appear to be well adapted to the purpose for which
they are contrived, and further improvements in their construction will
no doubt be introduced. Coal-cutting machines, which act either by
picking or gouging, have been found to work more economically than
manual labour, while at the same time much less coal is destroyed and
reduced to slack. A matter of still more importance is the diminished
risk to the persons and lives of the employed, who, when working in a
constrained position, and consequently unable to relieve themselves from
the fall of a superincumbent mass of coal, are frequently crushed to
death. The application of machinery to cutting coal gives another
advantage of national importance, as, by enabling the working to be
carried into the deeper seams of coal which lie at so high a temperature
as to present serious or insurmountable difficulty to handwork, it will
render available to posterity new and hitherto inaccessible stores of
coal.
The hewers may possibly fear to be thrown out of employment by its
introduction on an extensive scale; but as it will relieve them from
their most irksome drudgery, and allow them to reserve their strength
for less injurious trial, they cannot but be thankful for the aid which
it affords them.
They are usually paid according to the number of baskets or tubs they
are able to fill. These are then conveyed by the putters through the
smaller or lower galleries of the pit to the headways, where they are
hoisted by the crow-men upon the rolleys or waggons for transporting the
coals from the crow to the shaft. The roads along which the rolleys are
driven are made sufficiently high for an ordinary horse by cutting away
the roof or the floor. Some of them are two miles long, and are kept in
repair by a rolley-wayman. Where tubs are used for the conveyance of
coal the whole way, no crow is necessary, but a lad, termed a ‘flatman,’
who links the tubs together at the level or the flat.
Next to the hewers, the putters are the hardest labourers in the pit;
and in some places their labour is even harder, for it is no easy matter
to push corfs or tubs, weighing from six to ten hundredweight, along
galleries which are often but three or four feet high, where the heat
not seldom averages about 78° Fahr., and in consequence of the increased
pressure of the air, water boils at 220°. The term ‘putter’ includes the
specific distinctions of the ‘headsman,’ ‘half-marrow,’ and the ‘foal.’
Where full tubs or baskets are to be pushed along the rails from the
hewers to the crow and the rolley-drivers, the headsmen take the chief
part; a half-marrow goes at each end of the train alternately with
another half-marrow; while a foal always precedes the train. At the
bottom of the shaft the ‘onsetters’ are stationed, who attach the tubs
to the ropes which hoist them to the surface. Besides these various
classes of workmen, we find the ‘shifters,’ who keep the galleries in
repair, and the little ‘trapper-boys,’ whose duty it is to open the
ventilating-doors whenever they hear the drivers or trains of coal-
waggons coming on one side or the other. Their task, though humble,
tedious, and requiring the least amount of intelligence, is of great
importance, as the numerous doors which they guard must remain open only
long enough for the passage of the trains, and must then be closed again
immediately, or the current of air needed to ventilate the mine would be
diverted in its course. It is hardly possible to imagine a more joyless
childhood than that of these little fellows, condemned to sit in
solitary gloom during the greater part of the day, and only comforted by
the sudden shout or song of a team-driver, approaching with his train of
waggons, and demanding the opening of the door.
Besides the workers underground, a number of labourers or artisans are
constantly employed above pit, from the ‘banksmen,’ whose duty it is to
see all things living and lifeless up and down the shaft, to the
‘staithmen,’ who attend to the staith or shipping place of coals. Many
find constant occupation in the raff-yard, where old waggons, ironwork,
and woodwork are duly hospitalled and refitted for fresh duty.
The daily work of the mine is conducted according to the strictest
discipline. The ‘resident viewer’ is supreme, and has subordinate
viewers, overseers, and wastemen, lamp-keepers, and other officers, who
have each their departments, and discharge their duties assiduously.
Thus a first-rate northern colliery establishment—where a total of more
than five hundred persons are variously employed—resembles a little
community in itself. Men of all educations, arts, grades, and duties,
and males of almost all ages, from ten years, are here; men, too, of all
appearances—from the gentlemanly viewer to the doubtful wasteman, and
from the underground workers-in-chief—the hewers—to the humble trapper-
boys.
The peculiar nature of his underground occupations, which condemns the
pitman, while working, to a position of great restraint, and taxes the
limbs and muscles in a very unequal manner, naturally influences his
outward appearance, so that he can be easily distinguished from every
other operative.
His stature is diminutive, his figure disproportioned and misshapen; his
legs being much bowed, and his chest protruding like that of a pigeon.
His arms are long, and oddly suspended. His countenance is not less
strange than his figure, his cheeks being generally hollow, his brow
overhanging, his cheekbones high, his forehead low and retreating, his
complexion pallid. Many of these bodily peculiarities or malformations
are probably hereditary. Pitmen have always lived in communities; they
have associated only among themselves, and have thus acquired peculiar
habits and ideas. They almost invariably intermarry, and it is not
uncommon in their marriages to commingle the blood of the same family.
They have thus transmitted natural and accidental defects through a long
series of generations, and may now be regarded in the light of a
distinct race of beings. In spite of the general march of intelligence,
their education is still very imperfect, and they are just emerging from
the greatest possible moral and intellectual darkness—an improvement due
mainly to the Wesleyan Methodists. The untiring labours of this
religious sect not only imparted to the colliery population in the North
of England a higher tone of moral feeling, but in their efforts to
instil religious principles into their minds, afforded them, through
Sunday-schools, a slight amount of education and an imperfect capability
of reading. These first seeds of improvement will, it is hoped,
gradually ripen into fruit, and oppose a strong barrier to the prominent
vices of colliers—gambling and intemperance.
A lack of mental and personal openness and boldness, a great inclination
to injury and theft, the grossest superstition, and a want of the
commonest economy and forethought, are likewise faults which are said to
be very common among them. Deception is so much a practice with them
that they deceive when no earthly advantage can be obtained from their
dishonesty.
Oh the other hand, the proofs of filial affection which they exhibit,
and the noble feelings and heroism which they display when explosions or
accidents take place, prove that the groundwork of their character is
good, and merely requires the influence of a better education to remove
a great part of the blemishes which ignorance has engrafted upon an
originally wholesome stock. Under every disadvantage, several eminent
men have sprung from their class. Thomas Bewick, the celebrated wood-
engraver, was early immured in pits; the late celebrated mathematician,
Dr. Hutton, was originally a hewer of coal; Professor Hann, of King’s
College, in London, was a boy working underground in a northern
colliery; and George Stephenson, the illustrious engineer whose
wonderful inventions have revolutionised the world, and who, after the
lapse of many ages, will still be reckoned among England’s most
illustrious sons, began life as a trapper.
Though the use of coal was already known to the ancient Britons, yet the
first public notice of the mineral is mentioned by Hume to have been in
the time of Henry III., who, in the year 1272, granted a licence to dig
coals to the town of Newcastle. Somewhat later in 1291, the abbot and
monastery of Dunfermline in Scotland obtained a similar grant. The first
coal is said to have been brought to London about the year 1305, where
it was used only by smiths, dyers, and soap-boilers. The smoke, which
was supposed to be injurious to health, caused great annoyance to the
wealthier inhabitants of the city, so that in 1316 its use was
prohibited by a decree of Edward I. This ordinance seems, however, to
have been but little attended to; for a few years later inspectors were
named to levy fines in case of its non-observance, and if these proved
ineffectual, to demolish the fireplaces arranged for the burning of
coal. The complaints against this fuel continued several centuries, for
as late as 1661 King Charles II. was prayed to remedy the nuisance by
banishing from town manufacturers who required large quantities of coal.
Yet, in spite of all the interdictions, complaints, and prejudices
arrayed against it, coal continued to grow in use; for as early as 1615,
Newcastle gave employment to about four hundred vessels, one-half of
which number supplied the demands of London. French ships even then
fetched coals in that port, and the Hanse towns conveyed them to
Flanders.
About the middle of the seventeenth century the coal trade,
notwithstanding an increase of price, required nine hundred vessels; and
fifty years later, half a million of tons were exported from Newcastle,
requiring fourteen hundred vessels for their carriage. During the
eighteenth century the northern coal trade constantly increased with the
steady growth of London, which in 1770, although not possessing one-
sixth of its present population, already consumed seven hundred thousand
tons; and it would have been impossible for the collieries to satisfy
the constantly growing demand if the invention of the steam-engine had
not lent its powerful aid to raise larger quantities of coal from a
greater depth, and to drain many works which otherwise would have been
deluged with water.
The other English coal-fields began to be worked at a much later period
than that of Newcastle, but rapidly grew in importance with the vast
increase of our manufactories and smelting furnaces.
The extraction of coal is indeed constantly increasing at a truly
gigantic rate. Thus, in 1845 our whole annual production was rated at
thirty-five millions of tons; in 1859 it amounted, according to
trustworthy returns, to sixty-eight millions; in 1865 it had advanced to
ninety-six million tons; and now probably exceeds one hundred million
tons—a mass so enormous that with it a girdle of coal three feet wide,
and about seven high, might be put round the earth.
The question of the duration of our coal-fields is evidently one of
great national interest. It has of late excited the attention both of
statesmen and philosophers, but unfortunately it is more easily put than
answered. While some authorities give us the cheering assurance that we
have enough to last us for the next two thousand years at least, others
limit our supply to three or four centuries, or assign even a couple of
hundred years as the period when our descendants will have to seek their
coals in the mines of other countries. The quantity of fuel left in the
Newcastle basin—the most anciently worked of our coal-fields—was
estimated by Mr. Hall, in 1854, at 5,121,888,956 tons. Dividing this
total by 20,000,000 of tons as the present annual consumption, the
future supplies of this famous coal-field would thus be limited to about
two hundred and fifty years—a very short period in the history of a
nation. The immense consumption of coal in the iron furnaces and
foundries of Staffordshire will probably lead to an exhaustion of that
coal-field even before Northumberland and Durham, for its area is
scarcely more than one-half of the area of the Northern Coal-field. It
has, indeed, one very thick seam of coal of from thirty to forty feet,
but this will not alone compensate the difference. The coal-fields of
Yorkshire, Lancashire, and Derbyshire, situated amongst the numerous
iron-works and manufactories, as well as large populations, justify a
similar prophecy; but, on the other hand, better prospects are held out
by the great coal-field of South Wales.
After deducting the coal practically unattainable from its depth, sixty
thousand millions of tons may be considered a liberal estimate of the
available mass. At the present rate of extraction (ten millions of tons)
this would give a supply for the next six thousand years; but supposing
the other sources to fail, the extraction of coal from the South Wales
basin would of course be increased to such an extent as to limit its
duration to six or seven centuries. It may be remarked that the largest
estimates of future coal supply are based on the assumption that mines
may be worked at a depth of four or five thousand feet; but this is very
problematical. Mechanical skill may indeed pierce shafts to this depth,
or even deeper; but the increase of temperature which is raised by one
degree for about every successive seventy feet, along with the
increasing density of the air, must ever oppose insuperable obstacles to
human labour at such a distance below the level of the sea. To the
natural heat and density arising from depth must be added the
corruptions arising from human perspiration, which are constantly on the
increase during working hours in working places. ‘We speak,’ says the
author of an excellent article in the _Quarterly Review_,[66] ‘from some
brief personal experience of what these things are at a depth of nearly
eighteen hundred feet, where the actual temperature varied from eighty-
five to eighty-six and a half degrees. Such experience is necessary to
qualify any man to judge of the vertical limit of human labour, and we
hesitate to fix it at more than two thousand five hundred feet, and
should fix it at that depth only for the hardiest of hewers and haulers
of coal.’
Footnote 66:
Volume cx.
The pressure of superincumbent strata, which renders the upholding of
the roof, even at fourteen or fifteen hundred feet, a problem of
ceaseless anxiety and expense, must also be taken into account. At
depths much exceeding two thousand feet, it is very doubtful if the
roofs could be securely upheld except at such an outlay as would
considerably raise the cost of extraction, while the coal itself would
be more and more dense, and therefore more and more difficult to
dislodge. For these various reasons, all the strata of coal situated
below the depth of two thousand five hundred feet, or at the very utmost
three thousand feet, may be considered as practically unworkable; and
thus sober-minded calculators, on comparing the available solid contents
of our coal-fields with the rate of extraction, have come to the
conclusion that a thousand years is the maximum of the probable future
supply of England and Wales. Adding to this the Scotch and Irish coal,
which are not included in the estimate, and swelling our account with
lignite and peat, we have at any rate sufficient materials for keeping
our fires burning for a good time to come, and may safely leave all
desponding views on the subject to distant generations.
Next to England, no European country has so rapidly increased its coal
production as the German empire, where, thanks to the railroads, the
consumption of mineral fuel is yearly extending over a wider range, and
gradually supplanting in many localities the use of wood. The official
tables inform us that in 1866, 432,594,926 cwt. of black coal, and
130,661,182 cwt. of lignite—together, about 28 million tons—were
produced, a mass considerably greater than the joint production of
France and Belgium, and equal to about seven twenty-fifths of the
production of England. The chief coal-fields are those of Upper Silesia,
of the Ruhr, of the Saar, of Waldenburg (in Lower Silesia), of Dresden
and Zwickau (in Saxony), of Aachen (Aix-la-Chapelle), Ibbenburen, and
Minden, which not only supply the greater part of Germany, but also
yield a considerable exportation to France, Switzerland, and Holland.
The German ports on the North Sea and the Baltic still largely consume
British coal, which, however, has been entirely driven from the Rhine;
and Berlin, which in 1860 burnt 202,970 tons of English coal, consumed
little more than one-half that quantity (123,401 tons) in 1865, in spite
of a considerable increase of population; while at the same time the
consumption of coal from Upper Silesia increased from 61,700 to 323,712
tons.
The small but thriving kingdom of Belgium, where the collieries of
Liège, Namur, and Hainaut give rise to a commercial activity unequalled
on the Continent, occupies the third rank among the coal countries of
Europe, its production in 1863 having amounted to 10,500,000 tons. The
provinces of Namur and Liège consume almost all the coal they produce,
while Mons and Charleroi, in Hainaut, export more than three millions of
tons to France.
This country, which, in 1862, produced 9,400,000 tons of coal, requires
at least 16,000,000 for its consumption, and imports the difference from
Belgium, England, and Germany. The chief coal-basins are situated in the
departments of the Loire, du Nord, Saône-et-Loire, and Gard, which
furnish about seven-eighths of the whole production. Austria, whose
principal coal mines are situated in Bohemia, produces about 3,500,000
tons. Spain possesses magnificent coal-fields in the Asturias and
Santanders, but as yet they have been but little worked.
Besides the coal-basins of the mother country, Britain is richly
provided with coals in many of her colonies. In New South Wales and
Tasmania, in Labuan and Farther India, in Hindostan and New Zealand, in
British Columbia and Honduras, valuable basins or seams of coal have
been discovered; and a magnificent coal-field, far surpassing in
magnitude those of the British Islands, extends from Newfoundland, by
Cape Breton, Prince Edward Island, and Nova Scotia, across a large
portion of New Brunswick. Thus far it has been but little worked, in
countries but thinly peopled, and covered for the most part with
boundless forests; but as from its general proximity to the sea it
offers every advantage for mining operations, a brilliant future may
safely be predicted for the lands it underlies.
The coal-fields of the United States are of still more ample
proportions, as they surpass in extent all the known coal-basins of the
world besides. Beyond the Alleghany Mountains we find the magnificent
Appalachian Coal-field, traversing eight of the principal States in the
American Union, from the northern frontiers of Pennsylvania to Alabama,
and covering a space of about sixty-five thousand square miles.
Of scarcely inferior extent are the vast coal-fields of Indiana,
Illinois, and Kentucky, which nearly equal in magnitude the whole of
England; and another smaller but highly important coal region is
situated between the lakes Erie, Huron, and Michigan, not to mention the
minor coal-basins scattered here and there from Texas to Missouri, and
from New York to Maine.
As yet, the Americans have not derived full benefit from their
extraordinary coal deposits; but the possession of so vast an
accumulation of _power_ allows us to predict a future of almost
boundless enterprise and production for that wonderful country.
While in most of our coal-seams deep shafts have to be sunk to obtain
the coal, and steam power has to be constantly employed to prevent its
submersion, the Appalachian Coal-field is intersected by three great
navigable rivers, the Monongahela, the Alleghany, and the Ohio, all of
which lay open on their banks the level seams of coal. At Brownhill, on
the first of these rivers, the main seam of bituminous coal, ten feet
thick, breaks out in the steep cliff at the water’s edge. Horizontal
galleries may be driven everywhere at very slight expense, and so worked
as to drain themselves, while the cars laden with coal, and attached to
each other, glide down on a railway so as to deliver their burden into
barges moored to the river’s bank. The same seam may be followed the
whole way to Pittsburg, fifty miles distant. Being nearly horizontal, it
crops out, as the river descends, at a continually increasing, but never
at an inconvenient, height above the Monongahela. Besides this main
seam, another layer of workable coal, six feet thick, breaks out on the
slope of the hills at a greater height. Here almost every proprietor can
open a coal pit on his own land, and the stratification being very
regular, he may calculate with precision the depth at which coal may be
won.
One of the most remarkable collieries in the world is that of Maunch
Chunk (or the Bear Mountain) in Pennsylvania, where an enormous bed of
anthracitic coal, nearly sixty feet thick, and probably caused by the
doubling back of a twenty-eight feet seam upon itself, is quarried in
the open air; the overlying sandstone, forty feet thick, having been
removed bodily from the top of the hill, which, to use the miners’
expression, has been ‘scalped.’
CHAPTER XXXIII.
BITUMINOUS SUBSTANCES.
Formation of Petroleum—Enormous Production of the Pennsylvanian Wells—
Asphalte used by the Ancients—Asphalte Pavements—The Pitch Lake of
Trinidad—Jet—Its Manufacture in Whitby.
The class of bituminous minerals exhibits a long series of inflammable
substances, which are supposed to be derived from the decomposition of
organic matter in the rocks containing them. Some (Petroleum—Rock-
naphtha) issue in a fluid state from the earth, while others pass by
insensible gradations from petroleum into pittasphalte or maltha (viscid
bitumen), and the latter as insensibly into the solid form of asphalte.
Certain bitumens, again, differ but slightly in composition from
bituminous coals, so that it is, in reality, very difficult to draw a
decided line between them. Hence it is highly probable that in petroleum
we see the product of a primeval vegetation which, under the influence
of chemical change and heat, has partly assumed a liquid form, and
oozing from the deep-seated strata in which it was confined by
terrestrial revolution, now permeates the superficial rocks, or exists
collected in subterranean cavities, whence it issues in jets and
fountains whenever an outlet is made by boring.
Petroleum springs have been known for many ages in Burmah, where there
are about one hundred wells from one hundred and eighty to three hundred
and six feet deep, each lined with horizontal tubes, but not all now
worked; at Baku, in the neighbourhood of the holy fires, already
mentioned; near the village of Amiano, in Parma, whence enough was
formerly obtained to light the streets of Genoa; at Zante, one of the
Ionian islands, which has furnished oil for more than two thousand
years, its petroleum spring having been mentioned by Herodotus; at
Agrigentum, in Sicily, which, according to Pliny, furnished a mineral
oil that was collected and used for burning in lamps; on the banks of
the Kuban, and many other localities; but it is only since the discovery
of the immense sources of supply in the north-eastern States of America
and in Canada that petroleum has become not only an article of the
greatest commercial importance, but a blessing to millions in all parts
of the world. It gladdens the long winter evenings of the Icelandic
peasant, and enlivens the hut of the Australian settler; it has found
its way into the remotest glens of the Alps, and to the distant sea-
ports of China. No wonder that its economical and cheerful light has
caused its consumption to increase with a rapidity almost without a
precedent in the annals of commerce. Though scarcely ten years have
passed since the American wells first began to pour forth their streams
of oil, no less than 670,000,000 gallons were exported in 1866 from the
ports of Philadelphia and New York. One-third of this enormous quantity
found its way to England; one-fifth to the port of Antwerp, its chief
staple place for Western Germany and the North of France; the remainder
was distributed among all the sea-ports of the world from Hamburg to
Hong Kong, and from the Cape to Valparaiso. When we reflect that this
amazing mass of liquid bitumen, which formed the cargo of no less than
seven hundred and thirty-one large vessels, must necessarily be
increased from year to year to meet a constantly increasing demand, it
might almost be feared that, in spite of the prodigality of nature, its
subterranean reservoirs must one day be exhausted.
Asphalte, a mineral pitch of a deep black colour and a conchoidal
brilliant fracture, is frequently found swimming on the surface of the
Lake Asphaltites, or Dead Sea, in Judæa, which receives its name from
the circumstance. It also occurs in many parts of Egypt, where it was
used for embalming. The ancients also frequently employed it, combined
with lime, in their buildings. Not only do we find the ruined walls of
temples and palaces in the East with the stones cemented with this
material, but some of the old Roman castles in this country are found to
hold bitumen in the cement by which their stones are secured.
‘It is a remarkable fact,’ says the late Dr. Ure, ‘that the substance
thus employed in the earliest constructions upon record, should for so
many thousand years have fallen well-nigh into disuse among civilised
nations; for there is certainly no class of minerals so well fitted as
the bituminous, by their plasticity, fusibility, tenacity, adhesiveness
to surfaces, impenetrability by water, and unchangeableness in the
atmosphere, to enter into the composition of terraces, foot pavements,
roofs, and every kind of hydraulic work. Bitumen, combined with
calcareous earth, forms a compact semi-elastic solid, which is not
liable to suffer injury by the greatest alternations of frost and thaw,
which often disintegrate in a few years the hardest stone, nor can it be
ground to dust and worn away by the attrition of the feet of men and
animals, as sandstone, flags, and even blocks of granite are. An
asphalte pavement rightly tempered in tenacity, solidity, and
elasticity, seems to be incapable of suffering abrasion in the most
crowded thoroughfares; a fact exemplified of late in a few places in
London, but much more extensively and for a much longer time in Paris.’
Many of the asphalte pavements made in England have, indeed, proved
failures; but as the proper proportions of the respective ingredients
may not have been maintained, further trials are advisable. At present,
although bitumen is employed, and with seeming advantage, as a cement
between paving-stones, its use in the formation of foot pavement has
been confined within narrow limits.
In Europe, the most extensive mine of asphaltic rock is undoubtedly that
of the Val de Travers in the canton of Neufchâtel; but the most
remarkable deposit of bitumen in the world is the celebrated Great Pitch
Lake in the island of Trinidad. With regard to its formation, Sir
Charles Lyell remarks that the Orinoco, which discharges its vast volume
of water right opposite to the island, has for ages been rolling down
great quantities of woody and vegetable bodies into the surrounding sea,
where, by the influence of currents and eddies, they may be arrested and
accumulated in particular places. The frequent occurrence of earthquakes
and other indications of volcanic action in these parts lends
countenance to the opinion that these vegetable substances may have
undergone, by the agency of subterranean fire, those transformations or
chemical changes which produce petroleum; and this may, by the same
causes, be forced up to the surface, where, by exposure to the air, it
becomes inspissated, and forms the different varieties of pure and
earthy pitch or asphaltum so abundant in the island. The Pitch Lake is a
mile and a half in circumference; the bitumen is solid and cold near the
shores, but gradually increases in temperature and softness towards the
centre, where it is boiling. The solidified bitumen appears as if it had
cooled as the surface boiled in large bubbles. The ascent from the lake
to the sea, a distance of three-quarters of a mile, is covered with a
hardened pitch, on which trees and vegetables flourish, and the best
pine-apples in the West Indies, called black pines, grow wild. As the
Trinidad pitch has been found by chemical analysis to be an excellent
material for the making of gas, it will probably become an important
article of commerce. The wonder is that it has been so long neglected.
[Illustration: THE PITCH LAKE, TRINIDAD. WEST INDIES. (_From an Original
Sketch._)]
Though Jet is frequently considered to be wood in a high state of
bituminisation, yet the fact that we find this beautiful substance
surrounding fossils, and casing adventitious masses of stone, seems to
show that a liquid, or, at all events, a plastic condition must at one
time have prevailed in its formation. This opinion is further
strengthened by the circumstance that petroleum strongly impregnates the
rock in which it is found, giving out a strong odour when it is exposed
to the air.
Jet occurs chiefly in the neighbourhood of Whitby in Yorkshire, the
estates of Lord Mulgrave being especially productive. The jet miner
searches with great care the slaty rocks, and finding the jet spread
out, often in extreme thinness, between the laminations of the rock, he
follows it with great care, and is frequently rewarded by its thickening
out to two or three inches.
The art of working jet is of very ancient date in this country, for the
Romans certainly employed it for ornamental purposes, and probably found
it in use among the Britons whom they conquered. Lionel Charlton, in the
‘History of Whitby,’ says that in one of the Roman tumuli, lying close
to the jaw-bone, he found the earring of a lady having the form of a
heart, with a hole in the upper end for suspension from the ear. There
exists no doubt that, when the Abbey of Whitby was the seat of learning
and the resort of pilgrims, jet-rosaries and crosses were common. The
manufacture was carried on till the time of Elizabeth, when it seems to
have ceased suddenly, and was not resumed till the year 1800, when
Robert Jefferson, a painter, and John Carter made beads and crosses with
files and knives. A stranger coming to Whitby, and seeing them working
in this rude way, advised them to try to turn it; they followed his
advice, and found it answer. Several more then joined them, and the
trade has been gradually increasing since; so that at present the total
annual value of the mourning ornaments made at Whitby and Scarborough
amounts to no less than 125,000_l._ About 250 men and boys are employed
in searching for jet, and between 600 and 700 are engaged in its
manufacture.
CHAPTER XXXIV.
SALT.
Geological Position of Rock Salt—Mines of Northwich—Their immense
Excavations—Droitwich and Stoke—Wieliczka—Berchtesgaden and
Reichenhall—Admirable Machinery—Stassfurt—Processes employed in the
Manufacture of Salt—Origin of Rock-salt Deposits.
Common salt is so necessary to man, and of such vast importance to the
manufacturer and agriculturist, that the processes by which it is
obtained are justly reckoned among the chief branches of industry.
In many of the warmer countries of the globe it is procured simply by
the evaporation of sea-water in shallow lagoons; in others, it gushes
forth in briny springs, or occurs in inland lakes, pools, and marshes,
or is extracted in the solid form of rock-salt from the bosom of the
earth.
The geological position of rock-salt is very variable; it is found in
all sedimentary formations, and is generally interstratified with
gypsum, and associated with beds of clay. In England its chief deposits
occur in the new red sandstone in the region around Northwich, in
Cheshire. They consist of two beds, which are not less than one hundred
feet thick, and are supposed to constitute large insulated masses about
a mile and a half long and nearly 1,300 yards broad. The uppermost bed
occurs at seventy-five feet beneath the surface, and is separated from
the lower mass by layers of indurated clay, thirty-one and a half feet
thick, with veins of rock-salt running between them. Hitherto only the
lower bed has been worked, for the upper deposits are of inferior
purity. These valuable mines were accidentally discovered in 1670 during
an unsuccessful sinking for coal; and as ever since that time they have
furnished a constantly increasing quantity of salt, amounting during the
last few years to more than 800,000 tons, the vastness of the
excavations may easily be imagined. To support the roof, which is about
twenty feet above the floor, and extends in some cases over several
acres, huge pillars not less than fifteen feet thick have been left
standing at irregular intervals, thus forming immense rows of galleries,
which even when illuminated by thousands of lights are lost in a dim and
endless perspective, which may well remind the spectator of the fabled
Hall of Eblis.
As the salt is detached from the rock by blasting, the grandeur of the
scene is not a little heightened by the frequent explosions re-echoing
through the spacious vaults, and booming like thunder from some dark and
distant gallery. For the transport of the salt underground, the roomy
passages are traversed in every direction by tram-roads, on which
waggons drawn by horses easily convey it from the place of extraction to
the bottom of the shaft. The chief part of the Cheshire salt (both
fossil and rock) manufactured is sent by the river Weever to Liverpool.
As it is rarely found of sufficient purity for immediate use, it is
first dissolved in water, and afterwards reduced to a crystalline state
by evaporating the solution. The necessary coals are mostly brought by
canal from the neighbourhood of St. Helens, and salt taken as a return
freight; so that, as in a clock-work where one wheel catches into
another, nothing is wanting to render its manufacture as economical as
possible.
Among the mineral treasures which nature has so prodigally bestowed upon
Great Britain, the salt-mines of Cheshire hold a conspicuous rank, as
they not only provide chiefly for our own vast consumption, but also for
that of many other countries. In 1864 the salt exports amounted to
596,063 tons, the total value being 281,443_l._ About one-third of this
immense quantity (183,097 tons) found its way to the British East
Indies, 72,201 tons to Russia, and 86,208 tons to the United States.
Next in importance to the Cheshire mines are the brine-pits of Droitwich
and Stoke, in Worcestershire, the former of which are said to have been
worked in the time of the Romans, and now chiefly supply the London
market. In 1865 their produce amounted to 185,000 tons, of which about
40,000 were exported.
At Droitwich the borings are only 175 feet deep, and so abundant is the
supply of brine that, if the pumps cease working, it speedily rises to
within nine feet of the surface, and if left unremoved, soon overflows.
The most renowned salt-mines on the continent of Europe are undoubtedly
those of Wieliczka, a small town of about 6,000 inhabitants, situated to
the south of Cracow, in a fruitful valley on the northern borders of the
Carpathian mountains. ‘After descending 210 feet,’ says Mr. Bayard
Taylor, an American traveller who visited them a few years ago, ‘we saw
the first veins of rock-salt in a bed of clay and crumbled sandstone.
Thirty feet more, and we were in a world of salt. Level galleries
branched off from the foot of the staircase; overhead, a ceiling of
solid salt, under foot a floor of salt, and on either side gray walls of
salt, sparkling here and there with minute crystals. Lights glimmered
ahead, and on turning a corner we came upon a gang of workmen, some
hacking away at the solid floor, others trundling wheelbarrows full of
the precious cubes. Here was the chapel of St. Anthony—the oldest in the
mines—a Byzantine excavation, supported by columns, with altar,
crucifix, and life-size statues of saints, apparently in black marble,
but all as salt as Lot’s wife, as I discovered by putting my tongue to
the nose of John the Baptist. The humid air of this upper story of the
mines has damaged some of the saints. Francis, especially, is running
away like a dip candle, and all of his head is gone except his chin. The
limbs of Joseph are dropping off as if he had the Norwegian leprosy, and
Lawrence has deeper scars than his gridiron could have made, running up
and down his back. A Bengal light, burnt at the altar, brought into
sudden life this strange temple, which presently vanished into utter
darkness, as if it had never been.
‘I cannot follow, step by step, our journey of two hours through the
labyrinths of this wonderful mine. It is a bewildering maze of
galleries, grand halls, staircases, and vaulted chambers, where one soon
loses all sense of distance or direction, and drifts along blindly in
the wake of his conductor. Everything was solid salt except where great
piers of hewn logs had been built up to support some threatening roof,
or vast chasms, left in quarrying, had been bridged across. As we
descended to lower regions, the air became more dry and agreeable, and
the saline walls more pure and brilliant. One hall, 108 feet in length,
resembled a Grecian theatre, the traces of blocks taken out in regular
layers representing the seats for the spectators. Out of this single
hall 1,000,000 cwt. of salt had been taken, or enough to supply the
40,000,000 inhabitants of Austria for one year.
‘Two obelisks of salt commemorated the visit of Francis I. and his
Empress in another spacious, irregular vault, through which we passed by
means of a wooden bridge, resting on piers of the crystalline rock.
After we had descended to the bottom of this chamber, a boy ran along
the bridge above with a burning Bengal-light, throwing flashes of blue
lustre on the obelisks, on the scarred walls, vast arches, the entrances
to deeper halls, and the far roof, fretted with the picks of the
workmen. The effect was truly magical. Presently we entered another and
loftier chamber, yawning downwards like the mouth of hell, with
cavernous tunnels opening out of the further end. In these tunnels the
workmen, half naked, with torches in their hands, wild cries, fireworks,
and the firing of guns (which here so reverberates in the imprisoned air
that one can feel every wave of sound), give a rough representation of
the infernal regions, for the benefit of the crowned heads who visit the
mines. A little further, we struck upon a lake four fathoms deep, upon
which we embarked in a heavy, square boat, and entered a gloomy tunnel,
over the entrance of which was inscribed (in salt letters) “Good luck to
you!” Midway in the tunnel, the halls at either ends were suddenly
illuminated, and a crash, as of a hundred cannon bellowing through the
hollow vaults, shook the air and water in such wise that our boat had
not ceased trembling when we landed in the further hall. A tablet
inscribed “Heartily welcome!” saluted us on landing. Finally, at the
depth of 450 feet, our journey ceased, although we were but half way to
the bottom. The remainder is a wilderness of shafts, galleries, and
smaller chambers, the extent of which we could only conjecture. We then
returned through scores of tortuous passages to some vaults, where a lot
of gnomes, naked to the hips, were busy with pick, mallet, and wedge,
blocking out and separating the solid pavement. The process is quite
primitive, scarcely differing from that of the ancient Egyptians in
quarrying granite. The blocks are first marked out on the surface by a
series of grooves; one side is then deepened to the required thickness,
and wedges being inserted under the block, it is soon split off.
‘The number of workmen employed in the mines is 1,500, all of whom
belong to the ‘upper crust,’—that is, they live on the outside of the
world. They are divided into gangs, and relieve each other every six
hours. Each gang quarries out, on an average, a little more than 1,000
cwt. of salt in that space of time, making the annual yield 1,500,000
cwt.!
‘The men we saw were fine, muscular, healthy-looking fellows; and the
officer, in answer to my questions, stated that their sanitary condition
was quite equal to that of field labourers. He explicitly denied the
ridiculous story of men having been born in these mines, and having gone
through life without ever mounting to the upper world.’
As far as explored, the salt-bed occupies a space of 9,000 feet in
length and 4,000 in width, and consists of five successive stages or
_stockwerke_, separated from each other by intervening strata of from
100 to 150 feet in thickness, and reaching to a depth of 1,500 feet.
Notwithstanding the immense amount of salt already quarried from this
wonderful deposit, which, according to authentic records, has been
worked ever since the twelfth century, and perhaps even much earlier, it
is estimated that, at the present rate of exploitation, the known supply
cannot be exhausted under 300 years.
It is a remarkable circumstance that sources of sweet water are found in
the mines in close proximity to the salt, a circumstance which is owing
to the latter not forming a continuous stratum, but being imbedded in
large nests or insular masses in the tertiary clay of the mountain, so
that in several places the water filtering from the top is able to gush
forth in the subterranean galleries without any saline admixture.
In the summer of 1868 a serious accident happened to the mines of
Wieliczka, which at one time was supposed to threaten their total
destruction. In the hope of discovering valuable potash salts, such as
occur at Stassfurt, in the vicinity of the rock-salt, a boring was
imprudently attempted at a great depth, through a contiguous aquiferous
stratum, and the consequence was that, instead of meeting with the
expected result, a powerful spring was tapped, which, pouring forth an
immense volume of water, filled the lower galleries. The inhabitants of
the village of Wieliczka, which is situated above the mines, were
terrified. They not only feared for the ruin of the mine, which afforded
them their chief means of subsistence, but dreaded also the falling in
of their houses, in consequence of the melting of the salt-pillars which
upheld the flooded galleries.
Fortunately their fears proved to be exaggerated, as the inundation,
which remained confined to the lower galleries, is now being rapidly
brought under by means of powerful steam pumps, and measures have been
taken for blocking up the spring. Even supposing the water to have
continued pouring in with undiminished force, and without any effort
being made to drain it off, the excavations are so vast that it would
have taken many years to fill them.
Besides the mines of Wieliczka, Austria possesses many other
considerable deposits of rock-salt in Gallicia (Bochnia), Hungary, and
Transylvania. In Salzburg (Ischl, Halstadt Hall), Tyrol, and the
neighbouring mines of Berchtesgaden, in Bavaria, the salt does not occur
in large solid masses, fit to be at once extracted from the bosom of the
earth, but imbues masses of gypsum and anhydrite, which become quite
light and porous when the salt has been removed by water. As it would be
too expensive to remove this compound, an ingenious method has been
contrived for introducing water into the mines from above, and drawing
it off again through an adit or lower gallery as soon as it is saturated
with salt.
The brine thus obtained at Berchtesgaden is then conveyed, by means of
pipes or conduits, to Reichenhall and Rosenhain, where the necessary
fuel for its evaporation is near at hand. The distance from
Berchtesgaden to Rosenhain is no less than thirty leagues; and between
both places many high mountains, steep rocks, and narrow gorges
intervene. The works which lead the brine over this distance, and
through all these natural obstacles, may therefore justly be considered
as a masterpiece of mechanical skill. As the pipes must often ascend
mountains, the highest elevation above the pit being 1,218 feet, and
then again slant down into ravines; as in many parts rocks had to be
levelled and forests cut down for the purpose of laying them, and as
they are subject to frequent damage in a severe climate, it may easily
be imagined that the greatest engineering power was required for the
execution of so grand a work.
Hydraulic machines serve to raise the brine over the mountains, and the
water-power of the rivulets descending from the heights is used for
forcing it upwards. The contrivance is so admirable that the small
machine at Berchtesgaden raises 270 cwt. of brine to a height of 311
feet by means of an equal weight of water descending from a height of
375 feet. In some parts the tubes of this colossal duct run along the
high road, in others tunnels have been pierced to shorten the distance.
Thus the Alpine rock-salt requires much ingenuity to be rendered
productive, while in other parts we find rock-salt cropping out on the
surface of the earth, so as to be very easily worked. The soil of many
extensive wastes in Asia and Africa is covered and impregnated with
salt, which has never been inclosed by superimposed deposits. Near Lake
Oroomiah, in Persia, it forms hills and extensive plains, and it abounds
in the neighbourhood of the Caspian Sea.
In the valley of Cardona in the Pyrenees two thick masses of rock-salt,
apparently united at their bases, make their appearance on one of the
slopes of the hill. One of the beds, or rather masses, has been worked,
and measures about 130 yards by 250, but its depth has not been
determined. It consists of salt in a laminated condition and with
confused crystallisation. That part which is exposed is composed of
eight beds, nearly horizontal, and having a total thickness of fifteen
feet, but the beds are separated from one another by red and variegated
marls and gypsum. The second mass not worked appears to be unstratified,
but in other respects resembles the former; and this portion, where it
has been exposed to the action of the weather, is steeply scarped and
bristles with needlelike points, so that its appearance has been
compared to that of a glacier.
The rock-salt deposit of Ilezk, about fifty miles to the south of
Orenburg, in Russia, is still more remarkable. On the sides of a crater-
like pit, which has been dug into the mass where it most nearly
approaches the surface, the rock-salt is seen standing in perpendicular
walls. On the west side of the gap a convenient staircase leads to the
bottom. The salt is hewn in large square blocks, which are afterwards
sawn into smaller pieces of eighty-five pounds. The regular annual
produce is fixed by Government at 700,000 pud, or about 10,000 tons, of
which part is furnished _gratuitously_ to the neighbouring Kirghise
hordes, who no doubt are made to pay dearly for their salt in some other
manner.
The labours in the mine are only carried on during the summer, and begin
by pumping out the water which has settled at the bottom of the pit from
the melting snow; while the transport to the next river by means of
sledges takes place during the winter. Were this mine situated in a less
barbarous or more accessible country, it might easily rival, or even
surpass, the produce of Cheshire. To the south of the pit, where the
regular mining operations, such as they are, take place, a great number
of old pits or holes may be seen, in which the Cossacks, Baschkirs, and
Kirghise used to provide themselves with salt before Government
undertook the regular working of the mine in 1754. These pits, some of
which are sixty feet square, and from six to eight feet deep, are
generally full of a saturated brine of a brownish colour, and are made
use of for bathing by the Kirghise, who justly consider them as an
excellent remedy for many diseases.
Before 1856 all the salt produced in Prussia was obtained from brine
springs, but since that time enormous beds of rock-salt have been
discovered in various parts of the kingdom. Those of Stassfurt, near
Magdeburg, produced 2,256,000 cwt. in 1866, part of which was exported
into foreign countries, through the ports of Lubeck and Hamburg. But the
mines of Stassfurt, besides rock-salt, contain also an inexhaustible
quantity of highly valuable potash salts, which are largely used for
agricultural purposes, and supply the wants of the numerous chemical
manufactories which have rapidly converted an obscure hamlet into a
flourishing seat of industry. At Speerenberg, about twenty miles to the
south of Berlin, the earth-borer has pierced through an enormous deposit
of rock-salt, more than two thousand feet thick, and at Segeberg, in the
province of Sleswig-Holstein, a shaft is now being sunk into a rich bed
of rock-salt, recently discovered.
The method of preparing the rock-salt, and the processes employed in
manufacturing salt from brine springs, are nearly the same in all salt-
works. The first process is to obtain a proper strength of brine, either
by saturating fresh water with the salt that has been brought up from
the mine, or pumping up the salt water from springs that have become
saturated by passing through saliferous beds. The brine obtained in a
clear state is put into evaporating pans and brought as quickly as
possible to a boiling heat (in the case of strong brine 226° F.), when a
skin is formed on the surface, consisting chiefly of impurities. This is
taken off, and either thrown away or used for agricultural purposes, and
the first crystals which form are likewise raked away and thrown aside
as of little value. The heat is then kept up to the boiling point for
about eight hours, during which time evaporation goes on steadily, the
liquid gradually diminishing, and the salt being deposited; it is then
raked out, put into moulds, and placed in a drying stove, to render it
perfectly dry and ready for sale.
When salt is to be prepared from the weak brines which are of common
occurrence in France and Germany, the brine is concentrated by natural
evaporation previous to the more costly application of artificial heat.
Having been first raised by pumps, it is then allowed to trickle in a
continuous stream down the surface of bundles of thorns exposed to the
sun and wind, and built up in regular walls between parallel wooden
frames. These evaporating works (_Gradirwerke_ or graduation-houses) are
frequently of an immense extent. At Salza, near Schönebeck, for
instance, the graduation-house is 5,817 feet long, the thorn walls are
from 33 to 52 feet high in different parts, and present a total surface
of 25,000 feet. According to the weakness of the brine it must be the
more frequently pumped up and made to flow down repeatedly over the
thorns in different compartments of the building. An immense quantity of
fuel is saved by this economical mode of evaporation.
The origin of rock-salt deposits is one of the most interesting
geological questions. According to some authorities, they were the
result of igneous agency, while others are of opinion that in every case
they have been deposited from solution in water. Their usual occurrence
in lenticular or irregularly-shaped beds, having a great horizontal
extension, favours the aqueous theory, for masses protruded upwards, or
sublimated by volcanic power, are generally found to occupy vertical
fissures. To account for their formation we must suppose a sea such as
the Mediterranean cut off by an elevation of the land at its mouth from
its previous communication with the ocean, and gradually losing more
water by evaporation than it receives by rain and rivers. As thus the
amount of salt which it holds dissolved increases, deposits of rock-salt
will ultimately form at the bottom of its deepest parts, and subsequent
changes in the earth’s surface may then either conceal them under
superincumbent strata, as at Northwich, or leave them exposed, as in
many of the African or Asiatic wastes.
CHAPTER XXXV.
SULPHUR.
Sulphur Mines of Sicily—Conflagration of a Sulphur Mine—The Solfataras
of Krisuvick—Iwogasima in Japan—Solfatara of Puzzuoli—Crater of
Teneriffe—Alaghez—Büdöshegy in Transylvania—Sulphur from the Throat of
Popocatepetl—Sulphurous Springs—Pyrites—Mines of San Domingos in
Portugal—The Baron of Pommorão.
Though in every volcanic region of the globe sulphurous exhalations
arise from a great number of craters or solfataras, yet sulphur is but
rarely found in sufficient quantities to remunerate the miner’s toil. In
this respect the island of Sicily is unrivalled, for no other country
possesses such masses of this valuable, and in many cases indispensable,
mineral.
The numerous sulphur pits of Sicily, which occur in crevices or hollows
over a space of 150 geographical miles, are situated chiefly in the
southern part of the island, in the districts between the sea-border of
the province of Girgenti and the mountains of Etna, Mannaro, Castro
Giovanni, and Catolica. They are no doubt the produce of a vast volcanic
action which took place about the beginning of the tertiary period, when
the sulphurous fumes, rising through countless clefts or fumaroles from
the mysterious furnaces of the deep, condensed in the chalk and clay
grounds of the superficial strata.
In former times, as long as the chief use of sulphur was confined to the
fabrication of gunpowder, its production was comparatively
insignificant; but since the manufacture of sulphuric acid has become a
branch of industry of continually increasing importance, sulphur, the
ingredient necessary to its formation, has considerably risen in value,
and now constitutes the chief article of Sicilian exportation.
Girgenti, the most important town on the south coast of the island,
though its dirty miserable streets and its 15,000 inhabitants form a
melancholy contrast to the wealth and luxury of ancient Agrigentum,
within whose lofty walls a population of 800,000 souls is said to have
existed, owes to the increase of the sulphur trade the slight dawn of
prosperity which has enlivened it during these latter years.
All the sulphur-pits in the south-west of the island send their produce
to the port of Girgenti, and on every road one meets with long files of
mules and asses loaded with sacks of sulphur.
The grape disease, against which this mineral is everywhere used in
France and Italy as the only successful remedy, has given a new impulse
to the sulphur trade by raising the price to about three times its
former value. The merchants of Girgenti did not neglect this opportunity
for making their fortunes, for as soon as the grape disease became a
national calamity for the chief wine-producing countries, they bought up
large tracts of sulphur-grounds, and thus acquired considerable wealth.
A visit paid by Dr. Häckel[67] in 1859 to the sulphur pits near Girgenti
proves that mining operations in Sicily are still in the primitive
condition described by all former travellers. Not even our commonest
improvements are known; the pickaxe and the spade are almost the only
implements employed, and with these the earth is excavated in the most
slovenly manner, wherever a vein promises to be productive. The
materials thus loosened from the rock are carried out of the mine in
baskets and thrown into large heaps, from which the sulphur is extracted
in the following wasteful manner. The conical mounds are covered with a
mantle of moist clay, in which some openings are left for the emission
of the smoke, and set fire to at the bottom. The melted sulphur collects
in grooves or channels, and flows into square forms, where it congeals
into a solid mass. This method, which is said to have been first
introduced by the Saracens, causes, of course, a great loss of sulphur;
but distilling ovens heated by coal have been found too expensive to
answer. Dr. Häckel traversed one of the longest excavations, which was
sometimes so narrow that he could only with difficulty pass, and then
expanded into high vaults whose roof was ornamented with beautiful
crystals of celestine and gypsum. The workmen were completely naked, on
account of the oppressive heat which reigns in these pits; and their
dark brown skins, sprinkled with light yellow sulphur dust, gave them a
very strange and savage appearance. Most of the inhabitants of Girgenti
are at present employed in the sulphur mines, and comparatively few are
engaged in cultivating the beautiful gardens and fields that extend from
the foot of the town to the sea, and occupy the site where once the
ancient city of Agrigentum rose from the shore to the terraced hills
which are still crowned with the ruins of her colossal temples.
Footnote 67:
‘Zeitschrift für allgemeine Erdkunde,’ No. 84, Juni, 1860.
On an average, the sulphur-ores of Sicily yield about sixteen per cent.
of brimstone, and the quantity annually produced has increased from
94,985 tons in 1851 to 184,173 tons in 1866. Besides Girgenti, the chief
ports from which sulphur is exported are those of Licata, Terranova,
Siculiana, Palermo, Messina, and Catania.
One of the most remarkable events in the history of Sicilian sulphur
mines occurred during the last century in the solfatara of Sommatino.
This celebrated pit, which is situated on the precipitous right bank of
the Salso Valley, took fire in 1787, through the negligence of the
workmen, and as may easily be imagined from the inflammable nature of
the materials, the conflagration caused the complete abandonment of the
pit. After two years, however, during which the fire raged incessantly,
the mountain suddenly burst asunder on its south-eastern flank, and a
stream of melted sulphur, gushing forth from the cleft, precipitated
itself into the neighbouring river. This phenomenon, which was evidently
caused by Nature having performed on a vast scale an operation similar
to that by which the sulphur is usually extracted from the ore, produced
a mass of the purest brimstone, amounting to more than 40,000 tons, so
that the owners of the pit, who had given up their property as totally
lost, became enriched by the very circumstance which had seemed to
menace them with utter ruin.
Next to the sulphur mines of Sicily, those of Teruel and Lorca, in
Spain, which in 1862 furnished 12,639 tons, are the most considerable in
Europe. The mines of Perticara di Talamella, in Italy, annually yield
about 4,000 tons; and the Austrian sulphur pits of Swoszowice, near
Cracovia, and of Radoboy, in Croatia, produced 1,867 tons in 1865.
In all these mines the sulphur has been deposited or condensed in times
long past, undoubtedly in the same manner as it is formed in the
solfataras of the present day, where the decomposition of the volanic
gases on reaching the atmosphere causes the precipitation of sulphur.
Most of these still active solfataras are unproductive in a commercial
sense, either from their inaccessible position in the crater basins of
enormous volcanoes, or from their situation in remote deserts, or from
the small quantities of the mineral forming on their surface.
The solfataras of Krisuvick in Iceland, for instance, are separated from
the nearest ports by such rugged lava-fields as to render the cost of
transport an almost insurmountable obstacle to their being worked with
profit. But though undeserving of the mercantile speculator’s attention,
these northern sulphur pits rank among the most striking natural wonders
of Iceland.[68]
Footnote 68:
‘The Polar World,’ p. 52.
The remote solfataras of Japan afford a more abundant supply. ‘The
sulphur,’ says Kämpfer, in his history of that singular country, ‘is the
produce of a small island which, from the great quantity it affords of
this substance, is called “Iwogasima,” or the Sulphur Island. It is not
above a hundred years since the natives first ventured to explore that
desert spot, which, from the smoke rising from its surface, was
previously supposed to be the abode of demons. At length a bold
adventurer obtained leave to visit the dreaded island. He chose fifty
resolute men to accompany him on his hazardous expedition, and on
landing found, instead of the fiends he expected to encounter, a
volcanic soil, covered in many parts with thick deposits of sulphur, and
emitting dense volumes of smoke from countless fumaroles. Ever since
that time the island yields a considerable revenue to the Prince of
Satzuma.’
One of the most celebrated solfataras is that of Puzzuoli, near Naples.
It may be considered as a nearly extinguished crater, and appears, by
the accounts of Strabo and others, to have been before the Christian era
in very much its present state, giving vent continually to aqueous
vapours, together with sulphureous and muriatic acid gases, like those
evolved by Vesuvius. This remarkable spot has attracted the attention of
naturalists and poets since the remotest antiquity, and Homer mentions
it in his immortal narrative of the peregrinations of Ulysses. The
process for the separation of the sulphur, which is condensed in
considerable quantities amongst the gravel collected in the circle which
forms the interior of the crater, is conducted in the following manner.
The mixture of sulphur and gravel is dug up and submitted to
distillation, to extract the sulphur; the gravel is then returned to its
original place, and in the course of about thirty years is again so rich
in sulphur as to serve for the same process once more.
‘The crater of the Peak of Teneriffe,’ says Leopold von Buch, ‘is now
but an immense solfatara. The sulphureous vapours which escape from
every part of the vast cauldron, decompose the rock, convert it into
white clay, and cover it in many places with beautiful crystals of
sulphur. By this constant chemical action, the soil towards the centre
of the crater has been rendered so soft that in many places great
caution is necessary to avoid sinking into the yielding mass, which has
a temperature higher than that of boiling water.’
A remarkable sulphur formation occurs on the rocks surrounding the
crater of the volcano Alaghez, situated in Northern Armenia. The sulphur
is precipitated in thick crusts on their walls, and as the summit of the
crater is inaccessible, the people of the neighbourhood, in order to
collect the sulphur, fire at it with musket balls, and pick up the
fragments thus detached.
Close beneath the summit of the Patuka, in Java, is a circular lake
about fifteen hundred feet in diameter. The borders are covered with a
rich vegetation; the water is clear and colourless, but appears
yellowish from the reflection of the sulphur which covers the whole
bottom of the lake. In 1818 Reinwardt found in this piece of water an
islet completely composed of sulphur.
After the eruption of the Tashem Idjem, another Javanese volcano, in
1796, such quantities of sulphur were formed that several hundred
shiploads could be gathered and exported as the produce of this single
volcanic paroxysm.
The mountain Büdöshegy, in Transylvania, exhibits the remarkable
phenomenon of sulphur caves. On entering one of these vast subterranean
crevices, incrustations of sulphur are seen to cover the lower part of
the walls; but respiration is still easy and free. On advancing a few
steps the air acquires a sharp acidulous taste, and the feet begin to
feel a warmth which gradually increases to an intolerable heat. On
advancing still further the lights are extinguished. A speedy retreat is
necessary, and imprudent visitors have been known to pay for their
curiosity with their lives.
In the island of Milo there are likewise numerous caverns the walls of
which are incrusted with sulphur and alum. A visit to these grottoes,
which annually yield about five hundred tons of pure sulphur, is not
without danger from the suffocating fumes that issue from their
crevices.
Some of the Arabian volcanoes also produce considerable quantities of
sulphur, such as the Dufan, which is called Djebel-el-Kebril, or
‘Sulphur Mountain’ by the Arabs, and is mentioned in the writings of
Herodotus.
Though the craters of volcanoes are generally almost inaccessible, yet
history mentions a curious instance where the most extraordinary
exertions were made for collecting sulphur above the regions of
perpetual snow. During the wondrous campaign which ended in the
overthrow of the empire of Montezuma, Cortez, being in want of powder,
sent a party under Francisco Montaño, a cavalier of determined
resolution, to gather sulphur from the smoking throat of Popocatepetl,
which rises, with its silvery sheet of everlasting snow, to the height
of 17,852 feet above the level of the sea. After traversing the lower
region, which was clothed with a dense forest, so thickly matted that in
some places it was scarcely possible to penetrate it, the track of the
Spaniards opened on a black surface of glazed volcanic sand and of lava,
the broken fragments of which, arrested in its boiling process in a
thousand fantastic forms, opposed continual impediments to their
advance. They now came to the limits of perpetual snow, where new
difficulties presented themselves, as the treacherous ice gave an
imperfect footing, and a false step might precipitate them into the
frozen chasms that yawned around. To increase their distress respiration
in these aërial regions became so difficult that every effort was
attended with sharp pains in the head and limbs. At length they reached
the edge of the crater, which presented an irregular ellipse at its
mouth more than a league in circumference. A lurid flame burned gloomily
at the bottom, sending up a sulphurous steam, which, cooling as it rose,
was precipitated on the walls of the cavity. The party cast lots, and it
fell on Montaño himself to descend in a basket into this hideous abyss,
into which he was lowered by his companions to the depth of four hundred
feet! This was repeated several times, till the adventurous cavalier had
collected a sufficient quantity of sulphur for the wants of the army.
Many mineral springs owe their medicinal properties to the
hydrosulphuric acid which they contain, and whose decomposition
frequently gives rise to the formation of sulphur. When the large marble
slab which covers the imperial source at Aix-la-Chapelle is removed at
the end of every twenty years, about two hundred pounds of sulphur are
collected from the walls above the spring.
Combinations of sulphur with metals, particularly with iron and copper
(pyrites), occur in much more considerable masses and in a far greater
number of localities than the pure uncombined mineral. Formerly the
sulphides of iron (52½ per cent. sulphur, 47½ per cent. iron) and copper
served only for the fabrication of vitriol and alum; but since the
progress of chemical science has allowed them to be profitably used for
the manufacture of sulphuric acid, they have acquired a far greater
importance. Our own mines, which are situated chiefly in the county of
Wicklow, produced in 1866 at least 135,000 tons of iron pyrites, besides
which an additional quantity of about 100,000 tons was imported from
other countries.
In Southern Spain the mines of cupriferous pyrites—particularly in the
province of Huelva, and in the Sierra de Tharsis, which on account of
the copper they contain were already worked in times anterior to the
Roman occupation, and give proof of their ancient importance by the vast
dimensions of their excavations—produced in 1863 no less than 246,137
tons. In Portugal the mines of San Domingos, in the province of
Alentejo, likewise afford a remarkable example of the mining industry of
the Romans, in the ancient adit which served for draining the works.
They merely used the ores that were richest in copper, and rejected the
poorer qualities, which form the immense mounds of scoriæ round the
mouth of the excavations. After having been abandoned for many centuries
the mines of San Domingos are once more diligently worked. Their newly
acquired importance is due chiefly to the enterprise of Mr. James Mason,
now Baron of Pommorão. A railroad nine miles long unites the mine with
the left bank of the Guadiana, which has been rendered navigable for
larger vessels for a length of ten miles. Moreover the port of Pommorão
has been excavated in the steep bank of the river for the convenient
shipping of the pyrites. Before 1858 a solitary hermitage was the only
dwelling at San Domingos, which is now a thriving village of five
hundred houses, with a handsome church and a railroad station. The
number of the workmen employed in 1866 amounted to two thousand, and
large works were being erected for the separation of the copper. In 1859
the produce of these mines amounted to 7,887 tons, and in 1866 it had
already risen to 167,028 tons, which formed the cargo of 544 ships. Such
are the wonderful changes which can be brought about when the right man
finds the right place for the employment of his energies. France
produced in 1866 about 100,000 tons of pyrites, Prussia 38,248 tons, and
Belgium 28,956 tons, so that the total production of Europe now probably
amounts to more than a million tons. In Canada the ore of a vast deposit
of pyrites is exported to the United States, where it serves for the
fabrication of sulphuric acid. Thus a substance scarcely noticed twenty
years ago has become an important article of commerce in both
hemispheres.
CHAPTER XXXVI.
AMBER.
Various Modes of its Collection on the Prussian Coast—What is Amber?—The
extinct Amber Tree—Insects of the Miocene Period inclosed in Amber—
Formidable Spiders—Ancient and Modern Trade in Amber.
Amber is a resinous substance, the produce of extinct forests that now
lie buried in the earth or under the bottom of the sea.
It is found abundantly on the Prussian coast of the Baltic, where it is
collected in many ways. After stormy weather it is frequently cast
ashore by the surf, or remains floating on the water. The amber-fishers,
clothed in leather dresses, then wade into the sea, and secure the amber
with bag-nets, hung at the ends of long poles. They conclude that much
amber has been detached from its bed when they discover many pieces of
lignite floating about. In some parts the faces of the precipitous
cliffs along the shore are explored in boats, and masses of loose earth
or rock, supposed to contain the object of search, are detached with
long poles having iron hooks at their ends. It is also dredged for on an
extensive scale at the bottom of the Frische and Curische Haffs, and
further inland large quantities are dug up out of the earth. That which
is washed ashore generally consists of small pieces, more or less
damaged, while the specimens obtained by digging or dredging are
frequently of large size and of a tuberous form, so that, though
inferior in quantity to the former, their value is probably ten times
greater.
Digging for amber is a favourite pursuit of the peasantry; and though in
many cases it proves unsuccessful, yet sometimes it is highly
remunerative. Near the village Kowall, a few miles from Dantzig, avenues
of trees were planted a few years back along the high road. On digging
one of the holes destined for their reception, a rich amber nest was
found. Favourable signs induced the landowner to persevere in digging,
and at length, at a depth of about thirty feet, such rich deposits of
amber were found as enabled him to pay off all the mortgages on his
estate.
The territories where amber is found extend over Pomerania and East and
West Prussia, as far as Lithuania and Poland, but chiefly in the former
provinces, where it is found almost uniformly in separate nodules in the
sand, clay, or fragments of lignite of the upper tertiary and alluvial
formations. It also occurs in the beds of streams, and in the sand-banks
of rivers. How far its seat may extend under the Baltic is of course
unknown. Amber is likewise met with on the coast of Denmark and Sweden,
in Gallicia and Moravia, near Christiania in Norway, and in Switzerland,
near Basle. It is occasionally found in the gravel-pits near London, and
specimens have been dug up in Hyde Park. At Aldborough, after a raking
tide, it is thrown on the beach in considerable quantities, along with
masses of jet.
On the Sicilian coast, near the mouth of the River Giaretta, many pieces
of a peculiar blue tinge are collected and sent to Catania to be cut and
polished.
Single pieces and even large deposits of amber are said to have been
discovered on the coasts of the Caspian Sea, in Siberia, Kamtschatka,
and China, in North America and Madagascar. These accounts, however,
require confirmation, as several other fossil or non-fossil resinous
substances so strongly resemble amber as to have deceived even well-
informed naturalists.
What is this substance, and how has it been produced? There is now no
longer any doubt that, like other vegetable resins, it has been secreted
by trees which have long since disappeared from the surface of the
earth, but once formed extensive forests on the islands or shores of the
vast sea which at that time covered the plains of Northern Europe as far
as the foot of the Ouralian chain.
How those islands disappeared, and how those primeval forests came to be
buried under land and sea, becomes apparent from the changes that have
taken place in the South Baltic lands since the last two thousand years
in consequence of partial upheavings and subsidences. According to the
oldest Prussian chronicler, Peter of Duesburg, whose narrative begins
with the year 1226, the waves of the Baltic at that time reached as far
as the present town of Kulm, and a century later vessels sailed as far
as Thorn. The present delta of the Vistula was a shallow morass, dotted
here and there with a flat island, and continued in that state until
towards the end of the thirteenth century, when dykes, raised by the
industry of man, prevented the constantly recurring inundations of the
river, and converted gloomy swamps into fertile meadows.
In other parts we find the sea incroaching upon the land. Since the
times of the Teutonic Order a whole province between Pillau and Balga
has been submerged by the floods of the Frische Haff; and the first
Christian church in Prussia, originally built five miles from the sea,
now stands close to the shore. Dense fir-forests rose in gloomy
monotony, but a thousand years back, where now the Baltic rolls its
waters; and where at that time ships lay at anchor we now find hillocks
of sand. After such changes in comparatively so short a time, we cannot
wonder that the islands of the amber period should have been replaced by
other lands and another sea.
We are indebted for the first accurate observations on the nature of the
amber-tree to Professor Goeppert, who proved, by the microscopical
examination of the cells of fossil pieces of wood that were veined or
streaked with amber, and thus evidently had secreted the resin, that
they proceeded from several coniferæ, belonging to the extinct genus
Pinites.
In many of our pines and firs we frequently find between the annual
rings crevices or interstices filled with resinous matter, but far less
abundantly than in the amber-trees. The only existing coniferous plant
that can in any way be compared to them is the _Dammara australis_, of
New Zealand, at the base of whose trunk masses of resin, weighing twenty
or thirty pounds, are frequently found. In Brazil Von Martius often saw
similar lumps at the foot of the copal-tree, which dropping from the
trunk had collected in considerable masses between the roots, thus
showing that the large rounded or globular pieces of amber must have
been formed in the same manner, while the thin and flat straight or
cupuliform pieces were moulded upon the rind, or between the annual
rings of the tree.
When we consider the abundant secretion of the amber-trees, and the
numberless ages during which they may have flourished, we cannot wonder
that, since the oldest historic times, every violent storm which stirs
up the ancient forest-grounds at the bottom of the Baltic casts the
valuable fossil ashore, and that in all probability future generations
will still be able to collect it in undiminished quantities.
Interesting in itself, amber acquires a still greater scientific
importance through the remains of extinct plants and animals which are
found imbedded in its substance, as in a transparent shrine. As, in the
present day, many a luckless fly is caught in the recently secreted
resins of the coniferæ and hymeneæ, thus also amber, while still in a
semi-fluid state, became the tomb of numerous insects and spiders. So
wonderful is their preservation that they seem to have lived but
yesterday, and yet how many millenniums may since have passed away; for
although the amber formation belongs to the miocene period, and is
consequently of modern date when compared with the forests of the coal-
formation, we still are separated from it by a vast series of ages.
[Illustration: INSECTS OR VEGETABLE SUBSTANCES ENCLOSED IN AMBER.]
The extinct organic world which is thus beautifully revealed to us so
greatly resembled the present vegetable and animal creation that, on a
superficial examination of the fossil remains contained in a rich amber
collection, one would hardly suppose them to be anything very uncommon.
The unlearned observer who connects the idea of a past world with
grotesque or gigantic forms, shakes his head with an incredulous smile,
and thinks that he has often seen similar flowers blooming in the
fields, or met with similar insects in the forest. Even the naturalist
is uncertain, until a closer inspection teaches him that each of these
so wonderfully preserved plants or animals possesses some distinct
characteristics which widely distinguish it from the analogous forms of
the present day.
Of the plants of the coal period we find not a single one existing in
the Amber Forest; the vegetation is much more complicated and various in
its aspect; and the numerous coniferæ indicate a climate similar to that
of the present northern regions. But arboreal growth was by no means
confined to the coniferæ, for evergreen oaks and poplars flourished
along with them.
Heath plants, chiefly belonging to genera similar to _Andromeda_,
_Kalmia_, _Rhododendrum_, _Ledum_, and _Vaccinium_, as testified by
numerous leaves, formed the underwood of these forests, a vegetation
similar in character to that of the Alleghany Mountains.
The deep shade of these primitive woods prevented the evaporation of
water, the ground remained damp and swampy, and the mouldering leaves
produced a thick layer of humus, on which flourished, no doubt, a dense
cryptogamous vegetation, as well-preserved ferns, mosses, lichens,
confervæ, and small mushrooms, partly growing as parasites on dead
insects, sufficiently testify.
But the vegetable remains of that ancient period are far surpassed in
variety and number by the embalmed relics of the animal creation. Among
2,000 specimens of insects collected by Dr. Berendt, to whom we owe the
best monograph on amber, this naturalist found more than 800 different
species.
Flies, phryganeæ, and other neuroptera, crustacea, millepedes and
spiders, blattidæ in every phase of development, beetles, bees, and a
large variety of ants, show a great similarity to the insect life of the
present day, and justify the conclusion that the contemporaneous animal
forms, whose size or peculiar habitat prevented their being embalmed in
amber, were comparatively no less abundant.
Whether man already existed at the time of the amber-formation is a
question which, of course, could only be thoroughly settled by the
discovery of some specimen of human workmanship _imbedded_ in the
fossilised resin. At all events, the amber-rings of rude workmanship
which have been found at a considerable depth below the surface of the
earth, along with rough pieces, sufficiently prove that man must have
been a very old inhabitant of the Baltic regions, for those remarkable
specimens of his unskilled industry have evidently preceded the
catastrophe which buried the rough amber under the earth, and must have
been exposed for the same lapse of time to the influences of the soil,
as they are all found covered with the same dull and damaged crust.