THE MENTOR 1918.05.01, No. 154,
The Story of Coal

COURTESY U. S. GEOLOGICAL SURVEY

FOSSIL FERN FROM COAL MINE

ONE

While the vegetable origin of coal is beyond question,
two rival views are current among geologists to
account for the deposit of ancient plant material in
the form of coal-beds, such as we now find in the
earth. One school of geologists holds that the coal plants
grew in great lagoons and swamps, like the mangrove swamps
of today, and that the modern coal-beds
mark the locations of these swamps.
From time to time these areas subsided
and were flooded with water to such a
depth that the plants were killed. Eventually
the decayed vegetation of the former
swamps was covered with a layer of mud
or sand. Later a slow upheaval of the
ground brought these regions again to the
surface; a new swamp formed, only to be
submerged again at a later period; and the
same process was repeated several times
in the course of hundreds of thousands of
years.

The bulk of evidence seems to favor
this view, but there is another. Perhaps
the coal-beds are not the sites of former
swamps, but of estuaries and ocean shores
where the plant material settled down, in
still water, after a long drift down the
ancient rivers from its place of origin. It
is not impossible that both explanations
are correct; some coal-beds having been
formed in one way, and some in the other.
With the progress of time the deposits of
sand were compacted into sandstone, and
the mud and clay into shale; while the
layers of vegetation were solidified by
pressure, some of their constituents were
vaporized and expelled by heat, and the
final product was coal.

The coal-measures abound in fossil
plants of species long ago extinct, and we
also find the molds or casts of plants that
have themselves disappeared, leaving only
their impressions in the mud by which
they were once enveloped. These records
of ancient vegetation are mostly found in
the rocks just above and below the coal-beds,
and not in the coal itself.

The plants of the Carboniferous Period,
during which most but not all of the coal-beds
were formed, bore a family likeness
to certain kinds of plants that flourish
today. Many of them were ferns, ranging
in size from the smallest species up to
great tree-ferns. Others resembled our
modern horsetails or scouring-rushes,
with their fluted and jointed stems, but
these calamites, as the geologists call them,
grew to the size of trees, sometimes eighty
or ninety feet in height. Some plants of
the coal age were like the modern cycads
(intermediate in appearance between tree-ferns
and palms); some were like the
ginkgo, a tree with leaves like those of
maidenhair fern, widely introduced into
this country from China and Japan. One
of the commonest and largest trees was
the lepidodendron, closely resembling, except
in its vastly greater size, the club-moss
or ground pine which we know so
well as a Christmas decoration.

The animal life of the period, of which,
also, abundant fossil remains are found,
included mollusks, fishes, crustaceans, insects,
spiders, thousand-legs, snails, reptiles
and lizards. Some of the insects
were a foot or more in length. Of cockroaches,
alone, more than five hundred
species have been found in the coal-measures.

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COURTESY U. S. BUREAU OF MINES

TIPPLE AT BITUMINOUS COAL MINE GARY, WEST VIRGINIA

TWO

When a coal famine is upon us there is a grain of
comfort in the reflection that beneath the soil of
this country, and within 3,000 feet of the surface,
there still lies 3,538,554,000,000 tons of coal. This
is the estimate of the United States Geological Survey. We
have mined coal wastefully and used it prodigally, yet we
have taken from the ground, up to the
present time, only a fraction of one per
cent. of the total amount at our disposal.
The whole of our “coal reserves,” if they
could be extracted and placed in a great
cubical pile, would form a mass 8.4 miles
long, 8.4 miles wide and 8.4 miles high. If
the coal thus far mined were piled up in
the same way, the cube would be 7,200 feet
long, 7,200 feet wide, and 7,200 feet high.[1]

The coal-producing areas of the country
are divided into six great divisions, known
as the Eastern Province, the Interior
Province, the Gulf Province, the Northern
Great Plains Province, the Rocky
Mountain Province, and the Pacific
Coast Province. The Eastern Province
contains probably nine-tenths of the high-rank
coal of the country. It is made
up of the anthracite regions of Pennsylvania
and Rhode Island, the Atlantic
coast region of Virginia and North Carolina,
and the great Appalachian region,
which embraces all the bituminous and
semi-bituminous coal of what is called the
“Appalachian trough.” The state of
Pennsylvania produces 47 per cent. of all
the coal mined in the country, and nearly
all of the anthracite.

The Appalachian region is the greatest
storehouse of high-rank coal in the United
States, if not in the world. “This near-by
and almost inexhaustible supply of
high-grade fuel,” says the Geological Survey,
“has been the foundation of the development
of the blast furnaces, the great
iron and steel mills, and the countless
manufacturing enterprises of the Eastern
states.”

The Interior Province includes all the
bituminous coal fields and regions near
the Great Lakes, in the Mississippi Valley,
and in Texas, and is made up of four distinct
sections—the northern (Michigan),
eastern (Illinois, Indiana and western
Kentucky), western (Iowa, Missouri, Kansas,
Oklahoma and Arkansas), and southwestern
(Texas). The coal of this province
is not, in general, of as high a quality
as that of the Eastern Province, but it is
very extensively mined, and is used for
heating and for generating power in the
many cities and towns of the Mississippi
valley and the Great Lakes region. Indeed,
extensive coal fields in proximity to
rich agricultural lands have made possible
the existence of such manufacturing centers
as Chicago, St. Louis and Kansas
City, and have been a leading factor in the
development of the vast railway systems
of the Middle West.

The Gulf Province is at present of little
commercial importance. Its coal is mined
only at a few places in Texas, and is mostly
lignite.

The Northern Great Plains Province
includes all the coal fields in the Great
Plains east of the Front Range of the
Rocky Mountains. The coals are of low
rank, being either lignite or sub-bituminous,
except in a few of the basins near
the mountains. The largest coal region
in this province is the Fort Union region,
lying in the Dakotas, Montana and Wyoming.
The amount of unmined coal in
this region is estimated to be twice as
great as that lying in the rich Appalachian
region, but it has been little worked, as it
is generally of poor quality.

The Rocky Mountain Province contains
a greater variety of coal than any
other province in the United States. It
includes all ranks, from lignite to anthracite,
but the prevailing ranks are sub-bituminous
and low-grade bituminous.

The coal of the Pacific Coast Province
is mined chiefly in the state of Washington,
where it has aided in developing the
industries of the Puget Sound region.
Oregon and California have small fields,
but the coal is of poor quality, and little
mining has been attempted.

PREPARED BY THE EDITORIAL STAFF OF THE MENTOR ASSOCIATION
ILLUSTRATION FOR THE MENTOR. VOL. 6, No. 6, SERIAL No. 154
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COURTESY BROWN HOISTING MACHINERY CO. CLEVELAND, O.

COAL CAR DUMPER IN OPERATION

THREE

In times gone by coal was carried out of the mines on
the shoulders of men and women, and then transferred
in wheelbarrows to the sailing-vessels or
wagons in which it was taken to market. In progressive
mines of today the coal is loaded in the mine into small
mine cars, which are hauled and hoisted to the surface by
electricity or steam. The mine cars are
dumped on an elevated platform called the
“tipple,” and the coal passes through chutes
or conveyors to the railway cars waiting
underneath to receive it. On its way downward
it undergoes a more or less elaborate
process of screening, breaking, picking,
washing, etc., according to the kind of coal
and the purpose for which it is to be used.

The coal reaches the market by three
general methods of transportation: (1)
All-rail; (2) rail to the seaports, where it
is used for bunkering steamers or carried
by vessels to other ports, foreign and
domestic; (3) rail to the Great Lakes, especially
Lake Erie ports, from which it is
carried to ports on the upper lakes, and
from the latter again by rail to markets in
the interior. The railroads themselves
use about one-fourth of all the coal mined
in this country. The coastwise coal-carrying
trade is mainly by wooden barges
towed by steamers, though much coal is
also carried by schooners, some of which
can carry a cargo of 5,000 tons or more.
About four per cent. of the bituminous
coal output goes to foreign countries.

“The consumption of coal,” says the
United States Geological Survey, “is a
measure of the industrial activity of a
people, for as yet coal is the main source
of mechanical energy. In this respect the
United States is the foremost nation, its
average annual consumption of coal for all
purposes being about five tons per capita.
Prior to the present war in Europe the
consumption of coal per capita in England,
Belgium and Germany was about four
tons, in Russia a quarter of a ton, and in
France about 1.6 tons.”

Marvelous forms of labor-saving machinery
have been introduced to facilitate
the loading and unloading of coal. The
principal form of apparatus for transferring
coal either to or from a vessel is the
“bridge tramway plant,” which consists of
long steel bridges mounted side by side
on suitable rails so that they can be moved
into place over the hatchway of a vessel.
Huge buckets, which load and unload
themselves, are carried on a “trolley,” suspended
from the bridge, and transfer coal
at high speed from the vessel to the stock
pile or railway cars, or vice versa. The cost
of loading coal by this method is only a
cent or two a ton.

Another ingenious device is the “car-dumper.”
This powerful machine picks
up bodily from the railway track a car
loaded with a hundred tons of coal, overturns
it, and discharges its contents into
the hold of a vessel; after which it returns
the car to the track. It is capable
of handling fifty cars an hour. It is
equipped with special apparatus to prevent
the coal from being discharged too
violently, and thus being badly broken up.

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COURTESY POPULAR SCIENCE MONTHLY

CHARGING COAL IN A MODERN GAS PLANT

FOUR

The story of the coal products forms one of the most
romantic chapters in the history of applied science.
The marvels of fairyland are surpassed by the
achievements of the modern manufacturer in obtaining
from mere black rocks dug out of the ground not only heat
and light, but a bewildering variety of useful gases, liquids
and solids—drugs, chemicals, dyestuffs,
and so forth.

For hundreds of years it has been known
that when coal is covered or enclosed, to
keep out the air, and then heated for a
certain length of time, instead of burning
to ash it is converted into a porous grayish-black
substance called “coke.” This
material, which burns without smoke or
flame, is a valuable fuel for many purposes;
especially for use in blast-furnaces for the
smelting of ore. Nowadays coke is made
on a vast scale from certain grades of
bituminous and semi-bituminous coal.
The coal is heated in “coking-ovens,” of
which there are several kinds. The most
common form of oven in this country is
the “bee-hive oven,” which produces coke
only. Another type of coking-oven, more
generally used in Europe than in America,
is the “flue-oven,” which produces, besides
coke, a number of valuable by-products.

When coal is converted into coke it gives
off combustible gases. The idea of saving
these gases and using them for illuminating
purposes was first practically applied
in the latter part of the eighteenth century.
“Coal-gas” is made by heating coal in
a closed vessel, called a “retort.” It is a mixture
of hydrogen and methane (a compound
of hydrogen and carbon), with
small amounts of several other gases.
Most of the carbon in the coal remains in
the retort as coke, which is, therefore, a
by-product in the process of making coal-gas.
After the gas is given off from the
coal it passes through a series of vessels,
where, by chemical and other methods, it
is freed from ingredients which would impair
its value as an illuminant, but which
are saved and used for other purposes; the
most important of these are “coal-tar” and
“ammoniacal liquor.” The purified coal-gas
is finally conveyed to a gas-holder or “gasometer,”
from which it is distributed to the
consumers.

In recent times other methods of gas-making
have come into use. In one of
these nearly all the carbon in the fuel is
turned into a combustible gas by passing
air through the hot coal. The product is
known as “producer-gas,” and is very valuable
for use as fuel and as a motive power
in gas-engines, but it is not an illuminant.
A modification of this process, in which
steam is passed over the heated fuel,
gives a mixture of hydrogen and carbon
monoxide, known as “water-gas.” This is
also a valuable source of heat and power;
but for use as an illuminant it must be
mixed with a gas made from oil. It is then
known as “carburetted water-gas,” and is
very extensively used for lighting purposes;
either by itself or mixed with ordinary
coal-gas.

Of the by-products of gas-making, ammoniacal
liquor was, until recently, the
only commercial source of ammonia. Coal-tar,
formerly thrown away as worthless,
is today the source of innumerable substances
of immense value to science and
the industries. From coal-tar are obtained
benzine, toluene, xylene, phenol (carbolic
acid), naphthalene, anthracene, etc., and
these more direct products are combined
with one another or with other chemicals
to produce coloring matters, explosives,
perfumes, flavoring materials, sweetening
substances, disinfectants, medicines, photographic
developers—in short, a little of
everything. The total number of coal-tar
products runs into the thousands, and is
constantly being increased by fresh discoveries.

In Germany, just before the war, the
industries engaged in making these products
(no longer by-products, but far
more important than coke and gas) were
capitalized at $750,000,000. One firm
made no less than 1,800 coal-tar dyes, besides
120 pharmaceutical and photographic
preparations.

PREPARED BY THE EDITORIAL STAFF OF THE MENTOR ASSOCIATION
ILLUSTRATION FOR THE MENTOR. VOL. 6, No. 6, SERIAL No. 154
COPYRIGHT, 1918. BY THE MENTOR ASSOCIATION, INC.

SMOKE PROBLEM—SCENE IN PITTSBURGH BEFORE AND AFTER THE SMOKE CURE

FIVE

Smoking is a costly and injurious habit. This is
not the beginning of an appeal on behalf of the anti-cigarette
crusade, but the introduction to a few
facts in regard to the far-reaching effects of smoky
chimneys. The smoke nuisance is as old as the use of coal.
In the fourteenth century a man was executed in London for
befouling the air of that city with the
fumes of “sea-coal,” as ordinary mineral
coal was once called in England, because
it was brought to London by sea. Under
Queen Elizabeth a law was passed forbidding
the burning of coal while Parliament
was in session, as the legislators believed
their health was likely to be impaired by
the smoky air of the city. What would
these bygone gentlemen say if they could
see modern London enveloped in one of
its famous “pea-soup” fogs—the color and
denseness of which are entirely due to coal-smoke?

Smoke is injurious to health, destructive
to vegetation, and fatal to architectural
beauty; and, along with all this, it is
enormously expensive. In the first place,
a smoky chimney means imperfect combustion,
and a waste of part of the heating
value of fuel. Then a smoky atmosphere
entails big laundry and dry-cleaning bills;
frequent repainting of houses; injury to
metal work; damage to goods in shops; excessive
artificial lighting in the daytime.
Pittsburgh was once the most famous
American example of all these evils, but
it has recently reformed. Before the Mellon
Institute of Industrial Research carried
out its elaborate smoke investigation
in that city, and, in consequence, stringent
smoke-abatement ordinances were
adopted, the annual smoke bill of Pittsburgh
was estimated at nearly ten million
dollars. The city was the paradise of the
laundryman, and light-colored clothing
was so little worn by the inhabitants that
it was known as “the mourning town.”

Throughout the United States it is said
that smoke causes an annual waste and
damage amounting to half a billion dollars.
No wonder numerous societies have been
formed to mitigate this evil, and a great
many laws have been enacted on the subject.
With a gradual increase in the use
of gas, coke and other smokeless fuels,
and improved methods of stoking furnaces,
the smoke nuisance is now happily
abating.

The pollution of the air by smoke is the
subject of systematic investigation and
measurement at certain places in this country
and abroad. Measurements of the
“soot-fall” made in Pittsburgh a few years
ago indicated an annual average deposit
of soot in that city amounting to 1,031
tons per square mile. London’s average
is 248 tons per square mile for the whole
city and 426 tons in the central districts.
In the heart of Glasgow the annual soot-fall
is 820 tons per square mile.

In Great Britain there is a Committee
for the Investigation of Atmospheric Pollution,
which has installed standard measuring
apparatus in sixteen English and
Scotch towns. The soot is collected in a
“pollution gauge,” consisting of a large
cast-iron funnel, enameled on the inside.
Projecting above the gauge is a wire screen,
open at the top, to prevent birds from settling
on the edge of the vessel. The gauge
communicates at the bottom with one or
more bottles for collecting rain-water, with
its solid contents. The bottles are emptied
once a month, when their contents are
weighed and analyzed.

Smoke is injurious to the respiratory
organs, conducive to eye-strain and responsible
for a lowering of human vitality.
The gloominess of a smoke-laden atmosphere
also has a depressing effect upon the
minds of many people.

PREPARED BY THE EDITORIAL STAFF OF THE MENTOR ASSOCIATION
ILLUSTRATION FOR THE MENTOR. VOL. 6, No. 6, SERIAL No. 154
COPYRIGHT, 1918. BY THE MENTOR ASSOCIATION, INC.

COURTESY U. S. BUREAU OF MINES

RESCUE PARTY ENTERING MINE AFTER EXPLOSION

SIX

Since the year 1870, some 60,000 men have lost their
lives as a result of coal mining accidents in this
country. This is approximately one fatality for
every 180,000 tons of coal mined. Gradually this
bad record is being improved, thanks to the combined efforts
of the United States Bureau of Mines, the mining departments
of the various states, the operators and
the miners themselves; but coal mining
remains a hazardous pursuit.

Falls of the roof are responsible for more
accidents than any other single cause.
These are likely to occur wherever the
roof is not fully timbered; especially in
the “rooms,” where the coal is being
blasted out. Many accidents also occur
in mine shafts, notwithstanding the
various safety devices with which the
“cage” or elevator is nowadays provided.

Fires and explosions attract a greater
amount of public attention than other
mining disasters on account of the large
number of victims so often involved in a
single occurrence of this kind. In the explosion
at the Courrières colliery, in France,
March 10, 1906, more than 1,100 miners
perished. This mine had previously been
renowned for its freedom from accidents.
Coal mine explosions are due to two principal
causes, which may act either separately
or in combination—fire-damp and
coal-dust. Accumulations of fire-damp,
or methane, locked up in the coal seams,
are liberated by the removal of the coal.
Frequently streams of this gas gush forth
with a hissing noise, and are known as
“blowers.” Fire-damp is explosive when
combined with certain proportions of air.
Apart from ventilation, which dilutes the
gas below the danger limit, the principal
precaution against explosives is the use of
safety-lamps, so constructed that the gas
cannot come in contact with a naked
flame. An excessive amount of coal-dust
in the air of the mine may also give rise to
explosions. Such explosions may be prevented
by wetting the dust, moistening
the air, or powdering the walls, roof and
floor with a non-explosive “rock-dust.”

After an explosion the air of a mine contains
a large amount of the deadly gas
carbon monoxide, and this “after-damp,”
as it is called, makes rescue work extremely
dangerous. Wherever suitable apparatus
is available, the rescuers carry with them
a supply of oxygen, by breathing which
they are able to live for some hours in a
poisonous atmosphere. The Bureau of
Mines has established a number of rescue
stations in the coal-mining districts and
maintains several mine safety cars for
hurrying rescue crews to the scene of a
disaster. The Bureau also instructs the
miners in first-aid and rescue work, and is
directing a national campaign in behalf
of “safety first” in mines.

Of the many methods that have been
devised for testing the air of mines for
noxious gases none is more interesting than
the use of caged canaries. These birds are
much more susceptible than human beings
to the effects of carbon monoxide, and
show signs of distress before a man begins
to feel any discomfort from the gas. In
many mines they are carried in routine
inspections. After an explosion the number
of rescuers equipped with oxygen apparatus
is always limited. These form
the advance guard, and are followed by
men without apparatus, who carry canaries,
by observing the behavior of which
they can tell how far they may safely
penetrate into the mine. The Bureau of
Mines has devised a special form of cage
in which the canary may be revived with
oxygen after being overcome with gas.
Experiments show that the bird may be
asphyxiated and revived again and again
without suffering any ill-effects; neither
does he acquire an immunity to poisoning
which would make him a less reliable
indicator.

PREPARED BY THE EDITORIAL STAFF OF THE MENTOR ASSOCIATION
ILLUSTRATION FOR THE MENTOR. VOL. 6, No. 6, SERIAL No. 154
COPYRIGHT, 1918. BY THE MENTOR ASSOCIATION, INC.

Courtesy of Brown Hoisting Machinery Co.

COAL-HANDLING MACHINERY ON PITTSBURGH COAL CO. DOCKS, DULUTH, MINN.

An electric trolley, with 5½-ton bucket, travels on each bridge, carrying coal from the boat to storage, or to
railroad car, or to screening apparatus in the rear

THE STORY OF COAL

By CHARLES FITZHUGH TALMAN

Editorial Writer for the Scientific American

MENTOR GRAVURES

FOSSIL FERN FROM COAL MINE · TIPPLE AT BITUMINOUS COAL MINE · COAL CAR
DUMPER IN OPERATION · CHARGING COAL IN A MODERN GAS PLANT · SMOKE
PROBLEM, SCENE IN PITTSBURGH BEFORE AND AFTER SMOKE CURE · RESCUE PARTY
ENTERING MINE AFTER EXPLOSION

Entered as second-class matter March 10, 1913, at the postoffice at New York, N. Y., under the act of March 3, 1879. Copyright, 1913,
by The Mentor Association, Inc.

Were it possible for the lump of coal that we burn in our
stove, grate or furnace to tell its story, it would take us
back millions of years to a time when vast areas of the earth’s
surface were covered with swamps, supporting a luxuriant vegetation.
No human being, mammal or bird yet existed. Animal
life included fish, shellfish and other aquatic species, besides
reptiles and insects. The vegetal forms resembled our modern ferns, horsetails,
club-mosses and evergreens. The atmosphere was heavily charged
with moisture, and a mild climate prevailed even in the polar regions.
Such were the conditions under which, during the great Carboniferous
Age, most of the existing coal-beds were deposited in the earth.

FOREST SWAMP OF THE CARBONIFEROUS PERIOD
(Coal Age). From a drawing by Potonié and Gothan

Coal is the litter of primeval swamps and forests. Year after year
the débris of the humid jungles accumulated in shallow water or in the
boggy soil, where it underwent partial decay, and was thus converted,
first of all, into the slimy or
spongy material known as “peat.”
Similar deposits are in process
of formation in the swamps of
the present day, and the peat
obtained from them is dried and
used as fuel on an extensive scale
in some parts of the world; especially
Ireland, Holland, Germany
and Scandinavia.

CONCRETE PORTAL OF A “DRIFT” MINE

Gradual changes in the elevation
of the land led to the submergence
of the prehistoric peat
bogs, during successive intervals
of time, by lakes or shallow seas.
Thus their vegetation was killed, and they were overspread with
layers of mud or sand, above which, during a subsequent period of
elevation, a new peat bog would form; and this process was repeated
several times. The conversion of the peat into coal appears to have
resulted from the pressure of the overlying strata, probably aided by
the internal heat of the earth. Much of its moisture was squeezed and
evaporated out; the proportions of its component gases were reduced;
and the result was a hard mineral, which has earned the popular name of
“black diamond” because consisting chiefly of carbon—the same chemical
element which, in a pure and crystalline form, constitutes the true diamond.
Chemically, coal consists of carbon; the gases hydrogen, nitrogen and oxygen;
sulphur; and ash (the mineral matter that remains after combustion).

Courtesy of United States National Museum

Comparative coal supplies of the world. The nick in the
smallest cube shows how much hard coal has been used
up. Soft coal cube has hardly been scratched

The record of these long-ago events is found when we sink a shaft
through typical coal-bearing strata. We pass through not one, but several,
layers of coal, which may vary in thickness from a fraction of an inch to
a hundred feet or more, and are separated by generally much thicker
layers of sandstone or shale (solidified clay). The layers of coal are known
as “coal-beds.” Unless a coal-bed is at least two feet thick it is hardly
worth working, and, ordinarily, the
thickness of a bed does not exceed
eight or ten feet. The shale or sandstone
above a bed is very commonly
found to contain the remains or the
impressions of the ancient plants
from which the coal was formed. A
study of these remains and casts
has made it possible to classify hundreds
of species of plants now extinct.
Fragments of plants are also sometimes
found in the coal itself, and
thin slices of coal frequently show a
vegetable structure
under the
microscope. Finally,
to furnish
conclusive proof of
the vegetable origin
of coal, we find
under the coal-bed
a layer known as
the “underclay,”
which is a fossil
soil filled with the
roots and rootlets
of the coal-producing plants. Different conditions of
formation, and also, probably, differences in the character
of the original vegetation, have resulted in the
production of different kinds of coal. The most important
heat-producing constituent in coal is the elementary
substance called “carbon,” and the simplest
classification of solid fuels depends upon the percentages
of fixed (non-volatile) carbon they contain, the
average percentages running as follows: Wood, 50%;
peat, 55%; lignite, 73%; bituminous coal, 84%; anthracite
coal, 93%. When fuel is burned the greater part
of it unites chemically with the oxygen of the air to
form certain invisible gases—especially carbon dioxide
and water-vapor—and only the ash remains.

From “Geology, Physical and
Historical,” by H. P. Cleland.
American Book Co., N. Y.

Section of coal-bearing
strata in Pennsylvania,
showing relative amount
of coal and barren rock
in a rich field

In the popular mind coal is classified as hard or
soft, while hard coal is further classified according to
the size of the lumps.
For both scientific and
industrial purposes
more elaborate classifications
are necessary,
and several have
been used or proposed.

COAL FIELDS OF THE UNITED STATES

Kinds of Coal

The United States
Geological Survey
classifies coals, first of
all, according to
“rank,” depending
upon both chemical
and physical characteristics.
Anthracite,
which contains the largest
percentage of carbon, ranks
highest, and lignite, with the
smallest percentage of carbon,
lowest. Coals of the same
rank are said to be of high or
low “grade,” according to
whether they contain a relatively
small or large percentage,
respectively, of ash and
sulphur. The ranks recognized
by the Survey are: Anthracite,
semi-anthracite,
semi-bituminous, bituminous,
sub-bituminous, and lignite.

Courtesy of U. S. Bureau of Mines

AN “ENTRY” IN A COAL MINE

Showing timbered roof

Courtesy of U. S. Bureau of Mines

COATING WALLS OF A MINE WITH CEMENT

To prevent coal-dust explosions

DRILLING IN COAL FOR BLASTING

“Anthracite” is the hardest
of coals. It was formed from
bituminous coal under the
crushing pressure due to the
upheaval of mountains or by
the intense heat of adjacent
molten rocks. Most American
anthracite is mined in eastern
Pennsylvania. The largest deposits
in the world are found
in China. Anthracite burns
slowly, with little smoke. It
is well adapted for domestic
use on account of its cleanness,
but is not an economical
fuel for steam-raising or general
manufacturing.

Press Illustrating Service

MODERN ELECTRIC LOCOMOTIVE

Used for hauling coal from the mines

“Semi-anthracite” also
ranks as a hard coal, though it is less hard than anthracite. Very little
is mined in this country, and it is generally sold as anthracite.

“Semi-bituminous” coal is a softer coal, which, when properly burned,
gives off but little smoke. The best semi-bituminous coal ranks highest
among the coals in heating value. It is the most valuable fuel for manufacturing
purposes; also for steamships, as it requires less bunker space
per unit of heat than any other coal.

“Bituminous” coal, or ordinary “soft coal,” burns readily, with a
smoky flame, and is the coal most commonly used for manufacturing purposes;
in fact, the bulk of the coal mined throughout the world belongs
to this rank. It includes a good many varieties, some of which are
extensively used in making coke, while others, such as “cannel” coal,
have been in great demand for use
in gas-works. Nowadays, however,
the widespread introduction of
“water-gas,”[2] which does not require
any particular kind of coal, has diminished
the demand for “gas coals.”

“Sub-bituminous” coal, or “black
lignite,” is common in some of our
western coal fields. It is a clean and
useful domestic fuel when used near
the mines, but is not very satisfactory
for shipment, as it shrinks
and crumbles under the effects of
“weathering” and is liable to spontaneous
combustion.

“Lignite” is the least valuable of coals, and is the form of coal which
is the least altered from the original peat. The Geological Survey applies
this name only to those coals which are distinctly brown and either
markedly woody or claylike in appearance. Lignite, as it comes from
the mine, contains from thirty to forty per cent. of moisture, and it
“slacks” or falls to pieces much more rapidly than sub-bituminous coal
when exposed to the air. It is hardly suitable for transportation.

For commercial purposes coal is also classified according to size.
The coal as it comes out of the mine,
without any sorting into sizes, is
known as “run of mine,” and the
semi-bituminous coals are commonly
shipped in this form. Most coals,
however, are passed over bars or
gratings, which constitute screens of
different degrees of fineness; each
screen permits all the lumps below
a certain size to fall through, and
thus the coal is divided into the
different standard sizes. The sizes
of anthracite, from the smallest
to the largest, are: rice, buckwheat,
pea, chestnut (or nut),
stove, egg, broken (or grate),
steamboat, and lump. Bituminous
coal is divided into slack, nut and
lump (the largest size). A mixture
of lump and nut is called three-quarter
coal.

The Modern History of
Coal

Press Illustrating Service

MODERN MINING MACHINE

for undercutting coal. The “cutter bar” is shown in front,
filled with “cutting teeth” set in a chain that travels around. See illustration opposite

Press Illustrating Service

SHAKER SCREENS IN A TIPPLE HOUSE

The coal passing over screens is graded according to size

“CUTTER BAR” AT WORK

The bar, with its cutting chain of teeth, makes a horizontal
cut deep into the bottom of the seam of coal. Blasting then
does the rest

The age of the steam-engine
is also the age in which the use
of coal has become widespread,
and the output of coal is a faithful
index of industrial progress.
Although the Greek writer
Theophrastus (about 300 B. C.)
mentions the use of coal as a
fuel, and its use was also known
to the ancient Britons and the
Chinese, it was virtually unknown
throughout the Middle
Ages. The first record of coal
mining in England is of the year
1180 A. D., and coal was first
shipped to London in the year 1240. It was long known as stone-coal,
pit-coal, etc., to distinguish it from charcoal; also as sea-coal, on account
of being carried to London by sea. Bituminous coal was first mined in
America in 1750, near Richmond, Virginia. Anthracite was discovered
in Rhode Island in 1760, and in Pennsylvania in 1766, but for many
years its value was not recognized. As late as the year 1812 Colonel
George Shoemaker, of Pottsville, was treated as an impostor and
threatened with arrest for attempting to sell a few wagon-loads of anthracite
in Philadelphia; methods of burning it were not understood, and
it was declared to be merely “black stone.” In the year 1820 only 365
tons of anthracite were
sold in this country, as
compared with the present
annual output of about
90,000,000 tons.

Before the days of the
railway coal was shipped
mostly by water in rough
boats called “arks,” which
floated down the rivers to
the seaboard towns. As
it was impossible to return
against the current, the
ark was sold with the coal
at its destination. A great
many arks were wrecked
in transit, and the whole
process of transportation
was a costly one. Only with the
introduction of steamboats, canals
and railways, did the coal
industry assume serious proportions.

The production of coal in
America has grown at an amazing
rate. In the year 1868 Great
Britain produced 3.6 times as
much coal as the United States,
and the output was also exceeded
by that of Germany. In 1899,
the United States took the
lead. At the present time, with an
estimated production for the year
1917 of 643,600,000 tons, the
United States is producing nearly half of all the coal mined in the
world. Great Britain ranks second, closely followed by Germany.

How Coal is Mined

A relatively small amount of coal is quarried near the surface of the
ground from open pits. The overlying soil is removed by steam-shovels,
and the coal is then blasted out and shoveled into cars.

Most coal is mined underground. Access to the coal-beds is obtained
either by sinking a vertical “shaft” or by driving a tunnel, according to
the location of the beds. A tunnel driven at a steep angle is called a
“slope.” A horizontal tunnel leading into a coal-seam is called a “drift.”
In this country few coal
mines are more than 300
or 400 feet below the surface,
and the deepest is
about 1,600 feet. Much
deeper mines are found in
Europe, especially in Belgium.

Press Illustrating Service

ROTARY DUMP IN A TIPPLE

Showing a coal car half turned over in order to dump contents

Courtesy of “Coal Age”

SPIRALIZING MACHINES

which, by rotating motion, separate the coal from slate

Courtesy of U. S. Bureau of Mines

MODERN HEADFRAME, BINS AND TRESTLE

Of fireproof construction. Anthracite coal mine

American mine shafts
are generally rectangular
and are divided into two
or more compartments.
Where a shaft passes
through water-bearing
strata it must be provided
with a tight lining, or
“tubbing,” to prevent
the mine from being
flooded. All water that enters
the mine collects in an excavation,
or “sump,” at the bottom
of the shaft, and must be
pumped to the surface.

The method of working
coal-seams most commonly
practiced in this country is
known as the “room-and-pillar”
system. One or more
tunnels, or “entries,” are first
driven from the bottom of
the shaft or the mouth of the
drift. These are the main
thoroughfares of the mine,
and are usually provided with
tracks, over which the mine
cars are hauled by mules or by some other method of traction—locomotives,
endless chains, etc. Secondary entries (“headings,” “butt entries,”
etc.) branch off from the main entries. Finally, the work of extracting
the coal consists of excavating open spaces, or “rooms,” adjoining
the entries.

Courtesy of “Coal Age”

MODEL COAL BREAKER

Note the neat and careful “upkeep” of the place

The actual mining is done in the rooms, and different methods are in
use. Anthracite is generally “shot from the solid”; that is, blasted
out from the face of the coal without any preliminary cutting. This
method is objectionable, especially in bituminous mines (where it is, however,
much practiced), because the large charges of powder it requires
produce a great deal of coal-dust and weaken the roof and pillars, often
leading to falls of coal and
fatal accidents. A better plan
consists of “undercutting”
the coal before it is blasted
out. A long groove is made
at the level of the floor, either
with a pick or with a coal-cutting
machine. Holes are
then drilled some distance
above the groove for the insertion
of the blasting charges,
and the coal is blasted down.
A single shot will sometimes
dislodge a ton or two of coal.

The next step is to shovel
the coal from the floor into a
mine car, which is then pushed
into the adjacent entry. The miner attaches a numbered tag to the car,
so that he will be duly credited for his work, which is paid for by the ton.
The loaded cars are eventually hoisted or hauled out of the mine, to be
weighed and discharged above ground.

The final step in working a coal-seam by the room-and-pillar method
is to mine out the thick walls or pillars of coal, which are originally left
between adjacent rooms to support
the roof. As this work proceeds the
worked-out sections are filled with
waste rock, or the roof is allowed
to fall. The object is to leave as
little coal in the mine as possible, but
practically it is rare that more than
60 or 70 per cent. is recovered.

One feature of a coal mine that
must be carefully planned is the system
of ventilation. This is provided
not merely for the comfort of the
miners, but to prevent, as far as
possible, the accumulation of poisonous
and explosive gases. There are
always at least two airways leading
into the mine (one or both of which
may also be used for hoisting or
other purposes), known as the
“upcast” and the “downcast,” according
to the direction in which the
air passes through them. A current
of air is maintained either by keeping
a fire burning at the bottom
of the upcast or by the use
of powerful fans or blowers.
A system of tight
trap-doors prevents the
air from taking a short cut
between the downcast and
the upcast, and thus leaving
the greater part of the
mine unventilated.

Courtesy of “Coal Age”

MINING FROM THE OUTSIDE

Stripping the surface of a coal-bed with steam shovel, at Pittsburg, Kans.

Courtesy of U. S. Bureau of Mines

WATCHING THE CANARY

for indications of poisonous coal gas. Reserves testing the air
of a mine after an explosion

Courtesy of U. S. Bureau of Mines

MEMBERS OF RESCUE TEAM

Showing apparatus worn on entering mines
after explosions. This device sustains a man
for two hours

The coal in the mine
constantly gives off various
gases, one of which, the
notorious “fire-damp”
(methane or marsh-gas), is
responsible for many
explosions. In recent years it
has been discovered that coal-dust
itself, when mixed with the
right proportion of air, is violently
explosive. Mine explosions
may be minimized by requiring
the use of “safety-lamps” (oil,
gasoline, or electric); by providing
devices to prevent sparking
in electrical apparatus; and by
using for blasting operations only
so-called “permissible” explosives,
which give a shorter and
cooler flame than black powder.
Coal-dust explosions can be
largely prevented by wetting the
walls of the mine, or by the new
process of “rock-dusting,” which consists of applying dry incombustible
powdered rock to all surfaces. Unfortunately, none of these precautions
are employed as generally as they should be.

Press Illustrating Service

SAFETY DEVICE IN COAL BUNKER

In case of a “coal slide,” a man may be pulled
out before he is buried and stifled

The elevator used for hoisting in the mine shaft is called a “cage.”
After the mine cars reach the surface they pass upon an elevated structure
called the “tipple.” This is generally the most conspicuous feature of a
mining property above ground, and provides
facilities for screening and otherwise
“preparing” the coal as it passes down
chutes to the railway cars underneath. The
more elaborate structure used for anthracite
is called a “breaker”; it includes
machinery for crushing the coal and arrangements
for removing “slate” and other waste
rock by hand picking or otherwise.

Coal mining in this country gives employment
to an army of 765,000 men. The
word “army” has a sinister appropriateness
in this connection, since out of every thousand
men employed in the industry three
are killed and one hundred and eighty
injured annually.

The World’s Coal Resources

In order of output, the leading coal-producing
countries of the world are:
United States, Great Britain, Germany,
Austria-Hungary, France, Russia, Belgium,
Japan, China, India, and Canada. The
total production during the latest year
for which data are available was about
1,346,000,000 tons.

How long will the world’s coal supply
last? This is a question to which various
answers have been given. Geologists are
able to furnish a rough estimate of the
amount of coal now in the ground and near
enough to the surface to be mined; but
with the growth of the world’s industries
the demand for coal is increasing by
leaps and bounds, and nobody can safely
predict how much will be needed at any
future time.

The world’s “coal reserves”—that is,
the amount of coal remaining unmined—are
estimated at 8,154,322,500,000 tons.
In the United States it is estimated that we
have used only four-tenths of one per cent.
of our available coal supply. At the present rate of consumption the coal in
this country would last about 4,000 years; but if the present rate of increase
in consumption should be
maintained, it would last only
100 years!

Fortunately for posterity
there are sources of heat, light
and power which are not, like
the fuels, exhaustible. Water-power,
for example, is a permanent
asset, and there are other
inexhaustible sources of energy,
such as solar heat and the
internal heat of the earth,
which Man’s ingenuity will
someday turn to good account.

Courtesy of “Coal Age”

CARS FOR CARRYING EXPLOSIVES INTO MINES

SUPPLEMENTARY READING

⁂ Information concerning these books may be had on application to the Editor of The Mentor.

Coal is “a burning question,” that has
to be met and answered every day. It
supplies heat, light and power—and a
thousand and one useful by-products—and
it is an ever-present, ever-fruitful
subject of public and private discussion.
We average folk know something of the
varied uses of coal in the big affairs of the
world, but we know it more intimately
and vitally in the forms in which it ministers
to our own personal welfare. Coal,
in our everyday—and night—life, means
heat and light. It means home comfort—and
if this “coal comfort” is denied us,
or even curtailed, we raise an immediate
and mighty outcry. And why not? The
health of a community can be fatally
affected by a few heatless days. The
experience of the past winter has shown
us how dependent we are on fuel, not only
for luxury and comfort, but for life itself.

Why do we need so much heat? Many
of the peoples of the earth get along comfortably
with much less heat than we consider
necessary. Europeans and South
Americans call us a “steam-heated nation.”
Why do we have to surrender so
completely and abjectly to the domination
of Old King Coal? It is true, as
Owen Meredith said: “Civilized man cannot
live without cooks”; and light is all
important in turning night hours to advantage;
but why must we be so warm?
Humanity was not created in a warm room,
nor was the human race nurtured, in its infancy,
by a coal fire or a gas stove. Primitive
man was his own heater. He had to
discover fire, and then exploit its uses. He
was originally supplied by nature with a
warm body, and he now finds artificial
ways of making it warmer. Has not
civilization pampered us to a point that
has impaired our original heat-giving resources
and substituted a forced warmth
that has enervated us? The doctors tell
us that many diseases come out of artificial
heat—indoor diseases, they might
be called—the diseases that are treated,
and sometimes cured today, by foregoing
artificial heat and going back to nature.

Does this mean that I suggest reverting
to primitive conditions and giving up
heat? No, indeed. I suffered enough
last winter. I do not advocate giving up
heat—suddenly. But letting up gradually
on artificial heat, I do most earnestly
advocate. Most of us live an over-heated
existence—to the depletion of our
health. The steam pipe, like a huge
python, is closing its coils about us, and
gradually stifling our native vital resources.

On the coldest days of winter a
white-haired man, nearly seventy years
of age, may be seen walking New York
streets, without a hat, clad only in light
“Palm Beach” trousers, and a silk negligée
shirt, open at the throat. “He is
crazy,” you say. “Perhaps,” I answer,
“but at any rate he is healthy—and immune
from cold.” Heatless days mean
nothing to him. On a raw, drizzling day
in November last a slender man was
playing golf in a light woolen suit. A
companion player, weighing over 200
pounds, full blooded and hearty in appearance,
and bundled up in two heavy sweaters,
asked the lightly clad player if he
was not afraid of catching a fatal cold.
“No,” he answered, “you are the one that
gives me concern. If I had your clothing
on I would be a sick man. I am not
healthy enough to wear all those things.”

Which means that we would be better
off in health if we could accustom ourselves
to less heat; if we could live as
the people of some other nations do—comfortable
and content with heat enough
to take the chill off the air, and not demanding
that we shall be “kept going”
by means of artificial heat outside of our
own natural heat-giving apparatus. We
make caloric cripples of ourselves by giving
crutches to nature in the form of
roaring furnaces and hissing steam pipes.
Fresh cold air is better for us than hot
air—in winter as well as in summer.
Would it not be worth while to form
a national Fresh Air Fraternity, based
on the principle of foregoing artificial
heat and developing the original body caloric?
We would then leave artificial heat
largely to infants, weaklings and invalids;
we would abolish several diseases altogether,
improve the mortality rate, and be
healthy, happy and vigorous. Incidentally,
too, we would have more coal for cooking
and other really
necessary purposes.

W. D. Moffat
Editor

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