By Henry Davies; published by The Welsh Educational Publishing Co, Merthyr Tydfil, 1904.
The book's author has " aimed at conveying a general impression of the mine, its parts, its appliances, and its rules; the principles underlying the methods adopted for extracting the coal; and the dangers and allurements of the life of a collier."
This is a selective extract of the book's contents by Gareth Hicks.
The chemist can show that coal is composed principally of what was once vegetable matter.
The geologist can point to the clear evidence of ferns, lichens, mosses and other plants to be found in coal beds many hundreds of feet below the earth's surface.
It can be proved beyond doubt that what is now coal was once, countless generations ago, luxurious vegetation growing undisturbed by man. Year after year it grew and decayed until many thousands of rotting roots below formed a rich soil for the growth of fresh plants, and so the process continued with the lower levels being compressed into beds of coal by the overlying strata.
The World's Coalfields
The area of the world's known coalfields is about 450, 000 sq miles, and it is considered that an even greater area of undiscoverd coal exists, in say China, Australia and North America.
The coalfields of Great Britain, despite only being some 12, 000 sq mls, produces 33% of total world production at the present time, it had been as much as 50% not so long ago..
The total quantity yet remaining in the earth is estimated to last 1,000 years at the present rate of output, namely 760,000,000 tons pa.
In 1900, the approximate output figures in tons for the principal coal-producing countries was;
- UK---225 million
Coal, and what we get from it
There is considerable variation in the amount of carbon found in coal as a result of the different degrees of compression and chemical change through which the vegetation forming it has passed before complete mineralisation took place. This results in several qualities or classes of coals, as follows
- Lignite---is wood in the first stage of alteration, has lost half its oxygen, but is not compressed. Contains a large amount of water, burns with a disagreeable odour and is of a brownish colour. Low heating power and leaves considerable ash. Found in Bovey Tracey in Devon.
- Cannel coal---chiefly used for gas making, contains a large quantity of hydrogen. Very dense, can be shaped into ornaments, doesn't soil fingers when handled. It kindles readily and burns freely and quickly. Sometimes called Canwyll [Welsh for candle] coal. Large amounts found in Lancashire and Scottish coalfields.
- Bituminous coal--- the proportion of carbon in this varies from 75% to 90%. Burns with more or less smoky flame. largely used for household purposes. Sometimes classified into 'free-burning', 'smoking' or 'flaming' coals. Not quite correct to call these coals bituminous as they contain no bitumen really. Best varieites found in Northumberland and Durham.
- Steam coal---these are dull black, ignite slowly, give off little smoke or flame, but intense heat. They do not fuse or cake together, often called ' free burning'. Intermediate in composition between bituminous and anthracite, mainly used for the production of steam. Best found in South Wales, the celebrated Aberdare 'Four Foot' seam having given the coals of this district a lasting introduction into the commercial markets of the world.
- Anthracite---the darker denser kinds gradually pass into the anthracite varieties which are the most highly mineralised forms known. Contain a much larger % of carbon than the others. Don't soil fingers when handled, they are jet black, very hard, and for that reason are sometimes known as stone coal. Split into shell like fractures when split.
In the South Wales coalfield a seam of coal which is bituminous in the eastern districts becomes steam in the central and ultimately a strong anthracite in the west. It is almost smokeless in burning and is much used for malt drying, and metallurgical purposes. Found in enormous quantities in Pennsylvania and a large amount also raised in South Wales.
The power contained in coal is surprising.
An eminent professor has calculated that ' a pennyworth of coal gas occupies 37 cu feet and weighs 1 1/4 lb. It generates c 1lb of water when burned and c 19 cu ft of carbonic acid gas. It can heat 30 gallons water from 60 degrees F to 110 degress F for a bath, or boil 8 gallons of water in kettles to make tea for 64 persons. It can work a 1 hp gas engine for an hour, or lift a weight of 88 tons ten feet high doing the work of 6 men for 1 hour. It can smelt 10lbs of iron and make a casting in 20 minutes. If burned in a 6" flue for ventilation purposes it can induce a supply of 80,000 cu ft of air..................A ton of coal will yield 10,000 cu ft of gas, 120 lbs of tar, 25 galls of watery liquid, and 1500 lbs of coke.
From coal tar obtained in gas works we get the aniline dyes which have almost entirely supplanted vegetable and other dyes.
Saccharin, one of the sweetest materials known, also comes from coal tar.
In fact the list of modern day 'essentials' which derive at least in part from coal tar components also include;
- head ache pills
- pine apple essence
- smelling salts
- sulphurous acids
- paraffin candles
- vanilla'essence of almonds
History of Coal Mining
The British coal trade has existed for over 7 centuries, and coal has been sold commercially since c AD 1215, the date of the signing of the Magna Carta.
But coal was known and used long before this, in c 371 BC, Theophrastus, in a treaty on 'Stones' mentions fossil substances " that are called coals, which kindle and burn like wood coals; they are used by smiths".
The first mention of the use of coal in England is often stated to be in 852 when it is recorded that the Abbot of Peterborough received ' twelve cart loads of coal', but it is doubtful whether the Anglo-Saxon here translated ' coal' does not mean peat.
In the reign of Edward I [1272-1307] a proclamation was issued prohibiting the use of coal in London because the nobles and gentry complained of ' the noisesome smell and thick air' caused by burning coal.
Towards the end of Elizabeth I's reign coal was becoming popular as a fuel owing to wood being in short supply.
The first attempts at working coal would doubtless have consisted in simply digging at the outcrops of the seams or where the coal was actually exposed on the surface of the soil.
Following this, bell-pits would be sunk, or levels driven where a few feet of overlay strata hindred access to the mineral. These were circular, 3 or 4 ft in diameter, and after being sunk to the seam would be widened out to allow the excavation of as much coal as possible without causing the upper strata to collapse.
In the C14, coal was being mined by shafts and adit levels, these adits were horizontal tunnels driven from the surface on a hillside at a gradient to drain water from the workings. The coal was raised up the shaft by a jack-roll, or common winch moved by manual labour, or by men or women carrying it on their backs up ladders.
These women [ bearers] were mostly the wives and daughters of the colliers, and waited on them to carry up their coals as they were cut. Another class, called 'fremit' bearers were allotted to colliers with no family to help them. Although employed in almost all colliery districts at that time, it was only in Scotland that they were in general use. They carried an average of 36cwt to 2 tons in a day and earned 18 pence per day wages. They started when they were aged 7 and went on till they were 50/60.
Narrow passages were driven into the coal seam leaving small pillars to support the roof. When difficulties arose from want of air, from too much water, or from the crush of the strata, the shaft and the mine were abandoned, and a new pit sunk not far off, the depth being only a few fathoms. In hilly districts where coal seams ' cropped out' to the sky in the sides of the hills, day drifts were the readiest means of access to the coal.
During the C15 to C17 some few improvements were introduced. The water being the greatest difficulty, attempts were made to raise it in several stages by chain pumps operated by wheels, or by horses, and then * gins were substituted for jack-rolls in raising coal. The depth of the workings was limited for the most part by the level at which free outlet for the water could be obtained through day drifts, so that in 1610 it was stated in Parliament that the mines of Newcastle would not last out more than about 20 years.
[* A horse gin was an apparatus where the horse walked round in a circle attached to an overhead flat wheel which was linked to , and drove, a head gear over the shaft].
The Cambrian Register  gives an interesting account of the working of a coal mine in this period.
"After driving a level to get off the water at a cost of 20/-, and sometimes much more, and they have found it [coal] ; they work sundry holes, one for every digger, some two, some three, and four, as the number of diggers is; each man works by candle light and sits whilst he works; then they have bearers, going always stooping by reason of the lowness of the pit; each bearer carries a basket six fathoms, when upon a stone bench he layeth the basket; here meeteth him another boy with an empty basket, which he giveth him, and taketh that which is full of coal and carrieth it far; when another meeteth him , and so on until they come under the door where it is lifted up.
In one pit there will 16 persons, whereof there will be 2 pickaxes, digging, 7 bearers, 1 filler, 4 winders, 2 riddlers, who riddle the coal when it is landed first to draw the small coal from the big by one kind of riddle, then the second riddling with a smaller riddle with which they draw smaller coals for the smiths. These persons will land about 80 or 100 barrels of coal in a day. Their tools about this work are pickaxes with a round pole, wedges and sledges to batter the rocks that cross their work."
"All times of the year is indifferent for working, but the hot weather worst by reason of sudden damps that happen, which oftentimes cause the workmen to swoon, and will not suffer the candle to burn, but the flame, waxing blue of colour, will of itself go out. They work from 6 o'clock to 6 o'clock and rest an hour at noon, and eat their allowance as they term it, which is sixpence to every man and fourpence in drink amongst a dozen. The danger in digging these coals is the falling of the earth, and killing the poor people, or stopping of the way forth, and so die by famine, or else the sudden irruption of standing water in old works."
As pits got deeper the system of working gradually changed. Knowledge gained by experience became of service, and it was now found advisable to leave large pillars of coal to support the roof whilst the other portions of the seam were worked away. But the pressure of the overlying strata was often sufficient to crush these pillars, and throughout a district of the mine what was called the ' thrust', or the breaking of the pillars, would set in; at other times, where the floor was soft and the coal hard, the ' creep' would occur, and the floor would be pressed upward until it reached the roof. The surface soil would subside during these movements in the mine, and buildings would be greatly damaged, and would frequently collapse.
Owing to frequent subsidences at the surface, the pillars of coal left to support the roof of the mine had to be increased in size proportionate to the depth of the seam, and gradually, as the shafts reached deeper seams, an enormous quantity of coal was left unworked in these pillars. To lessen the waste improved systems of working were introduced, and the whole of the coal is now in the majority of cases worked away.
Thus is seen the development of coal mines from when it was raised in buckets to where, at the beginning of the C20, more than 2000 tons per day are raised from a depth of over 500 yards through one shaft.
The first application of a rail to facilitate haulage or transport was at a colliery, and the early efforts to obtain some mechanical power to develop the mines led through a series of gradual improvements to the construction of the steam engine; it was at a colliery that the original crude locomotive was first tried.
The total ouput of coal in the year 1700 was 2,460,000 tons, but in 1750 the quantity had increased to 4,773,828 tons.
But the great expansion of the coal industry dates from the time when the steam engine came into general use. This was not only owing to the power which could then be applied to raising coal and water from deep shafts, but also to the immense demand for coal in the country created by the machine itself.
The great invention of Watt was speedily followed by the introduction of steam navigation and of railways ; and owing to the rapid succession of important innovations, the output of coal rose from 10 million tons in 1800, to 50 million in 1850, 185 million in 1891, and 227 million in 1902.
Whitefield in 1729 referred to the condition of the mining population of England, and described the colliers of that time as being lawless and brutal, and differing in dialect and appearance from the people of the surrounding country. They seem to have been much neglected by their employers and looked down upon by their neighbours as savages and outcasts.
In 1833, a Mr Carelton Smith, giving an account of a visit to the mining districts of Lancashire said;
" Children are sent down the mines with no more provisions than a bit of bread and cheese, and this they sometimes could not eat, owing to the dust and badness of the air. The heat was at times so great as to melt candles, and many of the roads were covered with water. The children were frequently beaten by the men for whom they worked, so much so, that they seldom left with a whole skin. Besides this, their backs were cut with knocking against the roof and sides of the roadways, and their feet and legs covered with sores and gatherings owing to the water. The children, boys and girls, earned their wages by drawing the coals in tubs along the galleries by means of a belt and chain, which passed around their waists. Many girls were thus employed, and after a time became crooked and deformed."
Owing to the rapid progress made in the science of mining, the picture today is totally different. Every possible care is taken to lessen the miner's risks, and to protect his life. His hours of labour are fewer and his surroundings in every respect are better. Collier boys have become colliery managers, and some of the noblest and bravest men of our country are now found amongst the workers of our coal mines.
Search for Minerals
Nothing relevant to coal-mining
The Earth's Crust
The greater part of coal is obtained from the Carboniferous formation, which again is part of the Paleozoic series of rocks which is the oldest, or lowest , also called Primary. The series next in order are termed secondary or Mesozoic, and the third in order Tetiary or Cainozoic [ recent life].
In South Wales, the Carboniferous formation is further subdivided as follows;
- Upper Pennant coals
- Lower Pennant coals
- Cockshot Rock
- White Ash series of coals
- Millstone Grit
- Mountain Limestone
In his search for coal, the geologist examines railway cuttings, cliffs, quarries, and beds of rivers, for signs of outcrops. He may be thus able to determine whether the rocks are carboniferous. Springs of water also frequently give valuable information, by their colour, as to the nature of the minerals in the beds below. Fossils may be present even in ploughed fields, or on the 'basset' edge of a coal seam. Geplogical maps and neighbouring mines also generally give reliable information as to the depth and angles of inclination of different coal seams.
Even in districts where coal has been proved and worked, it is aften advisable to sink trial boreholes before deciding where to sink shafts. The boreholes will also indicate the thickness and inclination of the seams to be worked, as well as their quality. Also the extent of any faults in the vicinity.
Notwithstanding all the above, sometimes calculations of geologists are upset by disturbances in the underlying strata, such as upheavals and subsidences caused by earthquakes and volcanic action. This can leave the coal in a basin or trough with the underlying strata cropping out on all sides, or even with thick bands of igneous rocks such as basalt dividing the seam into two parts.
Coal sometimes disappears and its place taken by boulders of sandstone resembling what may be seen in the bed of a river. The coal in this case appears to have been washed away by a stream which left behind traces of its course in the form of alluvial soil, such an occurrence is called a 'wash out'.
The greatest difficulties to be overcome by the mining engineer however arise from the presence of faults, which can entirely dislocate the strata so that a coal seam may be suddenly thrown up or down by many yards. The fault may be classed as upthrow, downthrow and reversed or trough.
Upthrow and downthrow is when the coal is thrown up or down; and when found on the opposite side expected from the hade[ the inclination from the vertical] of the fault then a reversed fault is formed. In the latter case an overlap of coal seams of as much as 100 yards can be formed. A zigzag fault is when several small faults are connected to each other. A trough fault is the result of the beds between two faults sliding downward for some distance. The vertical displacement through which the bed is moved is called its throw.
When subsidences in strata are uniformly placed the various beds continue the same angle of inclination and are said to be 'conformable'. If some beds are tilted up and others depressed then they have different angles of inclination and they are said to be 'unconformable'.
Rocks can be further classified into two main classes, viz. 'stratified 'and 'unstratified', according to how the were deposited. The former are deposited in layers one over the other by the action of water, called 'aqueous 'rocks; whilst unstratified rocks occur as amorphous masses and seem to have been more or less completely fused, as granite.
A general glossary of rock terminology ;
- Aqueous---or sedimentary/fossiliferous, formed under water
- Igneous---formed under great heat.
- Metamorphic---a term applied to either of the above types which have been altered by extensive chemical changes in the rocks themselves. For example, marble is limestone altered by the whole mass becoming chrystallised.
- Calcareous---like chalk, composed chiefly of lime and carbonic acid. Such as shells and corals [with addition of animal matter]
- Argillaceous---formed from clay or mud. Ganister is a siliceous rock with clay, found in the lower coal measures.
- Arenaceous---formed of sand. When sandy particles are cemented together various kinds of sandstone are produced.
- Carbonaceous---consist mainly of carbon combined with oxygen, hydrogen, and nitrogen, and a certain amount of earthy matter, which is left behind as ash when the rocks are burned.
- A Rock--any solid substance which forms a bed layer, or mass as a part of the crust of the earth , is called by geologists, a rock. Hardness has nothing to do with the term, beds of soft clay etc are rocks just as much as granite.
- A Conglomerate---or pudding stone, is a rock formed of pebbles or shingle cemented together in a matrix.
- A Breccia---a rock composed of angular and rough fragments of stones cemented together.
- Slickensides---the rocks at the sides of faults are often crushed, folded or broken, and the jaws of the fault are polished, scratched evidently by ribbing against each other, these are called slickensides by quarrymen,
- Loam---when sand and clay are mixed in the same mass of earth in considerable quantities.
- Marl---when there is much calcareous matter in a bed of clay it is called marl.
- Cleavage---many rocks, especially the older finegrained rocks, split into thin plates along planes not parallel to their bedding, roofing slates are thus produced.
- Foliation---a splitting of rocks but different to cleavage in that the laminate of foliated rock consists of different minerals, like the quartz, felspar, and mica of 'gneiss'.
- Lamination---a stratum is often made up of thin layers, each layer is called a lamina [a thin plate], and such rocks are said to be laminated. Rocks which are laminated split easily along these layers, thus paving slabs are obtained.
- Fossils---the remains , or traces of remains, of plants, or animals, found buried in the crust of the earth. In the carboniferous period, plant and animal life was abundant.
- Formation---express in geology any assemblage of rocks which have the same character in common, be it origin, age or composition. We thus speak of stratified and unstratified, freshwater and marine, aqueous and volcanic formations.
A Narrow escape
When the Bargoed shafts were being sunk an incident occurred which shows how coolness and courage will aid a man to escape from what appears certain death.
The sinkers were at work in one of the shafts, and the fuses, twelve in number, had been fired. As usual, the four men engaged in the work of preparing the shots rushed to the bowk, signalling at the same time to the banksman above 'raise bowk'. One sinker, however, William Bowen, who was the last to leave the burning fuses, scrambled on to the bowk just as it started on its upward journey. Failing to secure a firm grasp of the bucket he fell, after being hoisted about twelve feet, on to the smoking fuses below.
His comrades, feerful of the inevitable consequences, shouted wildly to those above, 'stop bowk', in order that they might return to the rescue of their companion. The engineman instantly brought his engine to a stand.
The frightened occupants of the bowk, however, realising in a moment that the fuses would take effect on the explosive before they could reach the shaft bottom and be again raised out of danger, decided to continue their upward journey, and 'up bowk' was frantically shouted.
Up they were hoisted, and soon the bank was reached by the bewildered men, who were every second expecting to hear the sounds of the shots, which were to carry the death message to the workman below.
Meanwhile, Bowen, had no sooner reached the end of his fall, and realised his perilous position, than he scrambled to his feet, and, after only a moment's hesitation, rushed to a fuse on a projecting piece of rock at the side of the shaft, drew it out quickly, and extinguished it.
Numbers two, three, four, five, six, seven, eight and nine were in a twinkling similarly treated.
Perceiving he had no time to take out the other three, he rushed to the projecting rock, crouched beneath it, and with his hands on his ears waited but a second for what he expected would be the end.
The shots went off, in less time than it takes to write the story, huge stones were thrown up into the shaft, and after striking against the sides rebounded, until they fell rattling on the rock beneath which the sinker had scrambled, and although the debris lay in heaps around, he miraculously remained uninjured.
Five minutes later, when his nervous comrades mournfully descended to bring up, as they thought, the mangled remains of their erstwhile companion, they found him coolly stretching his cramped legs in anticipation of the interesting story of a narrow escape from death, which he would have to relate to his surprised companions.
The existence of coal seams having been satisfactorily proved by prospecting or boring, and the proprietors having decided to sink shafts to work them, it is then necessary to fix upon the position, number, size, and form of the intended shaft.
The success, commercially, of a colliery will depend in great measure on the position of the shafts. The following facts need to be ascertained first;
- The extent of the field or royalty to be worked
- The number and probable thickness of the seams to be worked
- The output per day necessary to yield a profit on the capital invested
- The quantity of water likely to be met with
- The position of the shafts with regard to the markets, railways etc
- The number of shafts required
- The suitability of the ground for engine foundations, screens etc.
Depth of shaft
The depth at which coal seams are found varies considerably. Shafts have been sunk and mineral raised from;
Depth in feet
- Ashton Moss, nr Manchester---3360
- Pendleton Colliery---3485
- Harris Navigation---2279
- Dowlais, Cardiff---2220
- Dolcoath Mine[tin,copper], Cornwall---2582
- Produits Colliery,Mons---3937
- Prizbram Colliery, Bohemia---3300
- Tamarack [copper mine], North America---5100
These shafts and other boreholes give interesting information as to the nature of the earth's crust and the increase of temperature as we descend into the lower parts of the strata. Many causes modify this strata temperature, two examples of this variation are;
- Calumet and Hecla, Lake Superior
- Depth in feet---4580
- Feet for 1 degree increase in temperature F---223.7
- Dolcoath Mine, Cornwall
- Depth in feet---2124
- Feet for 1 degree increase in temperature F---70.0
Form of shaft
Shafts may be either rectangular , circular, polygonal or elliptical. The circular form is generally adopted in this country. It is the strongest form, on account of its having no long sides, the pressure thus being equally divided all round. It also presents less rubbing surface to the air, and gives a larger area for a given diameter.
In a circular shaft four plumb lines should be suspended at the extremities of the two diameters crossing each other at right angles. Constant care will be required with this plumbing to keep the shaft truly vertical.
Size of shaft
This is determined by the probable duration of the colliery, and the mineral expected to be raised, so that the size and number of the trams to be employed in winding must be considered.
Only a few of the little old pits like draw-wells about 4 1/2 feet in diameter can now be seen, as the size necessary for an output of 1500 tons of coal a day, from a depth of 600 yards or more, must be considerably larger than that required for a smaller output from a shallow mine.
Circular shafts now reach a diameter of 22 feet in this country, and in America rectangular shafts may be found 45 feet 10 inches long by 11 feet 5 inches wide.
Knowing the depth of the shaft, the speed at which each winding is to take place, and the time occupied in changing the tubs on the cage, and allowing a margin for interruption, the number of tubs to be raised at each lift is easily found. Then after deciding how many decks or platforms there are to be in a cage and the number of tubs on each deck, the size of the cage and of the shaft may easily be decided.
The first operation in sinking is to get down to the solid regular strata, technically called the stonehead: generally loose drift ground or alluvial deposits have to be passed through before firm ground is reached. The surface soil is removed so that the excavation may be a few feet more in diameter than the finished shaft. As this first portion will probably be in soft ground it can be excavated by pick and shovel.
When a depth of ten or twelve feet of soil has been removed, a round of cribs made of oak or elm, and about five inches square, is laid at the bottom, which should be accurately levelled for the purpose. The sides of the shaft are supported during these first stages by sinking in the following manner. About three feet above the first crib is placed another crib, supported upon short props, called punch-props, and set upon the crib below. Then above this second crib is placed another, similarly supported, and so on until the top most crib is some two or three inches above the surface.
Behind the cribs timbers or long planks like flooring boards, called backing-deals are placed to keep the smaller portions of the soil from breaking away. The whole set is then bound together by long planks called stringing-deals, which are placed in front of the cribs and nailed to them. Sometimes, iron binding rings are used instead of cribs to support the backing deals.
Raising the debris
After the first few feet, the material excavated is raised by means of buckets or kibbles attached to a rope passing over a pulley in a temporary headgear.
After a firm foundation of rock has been reached, a bed is prepared with backs or chisels to receive the walling crib. This crib is made of wood or cast iron ,and after being laid perfectly level, receives the first part of the walling which may consist of bricks or stones. At this stage the walling may be about 9 inches thick, nearer the surface it reaches 2 or 3 feet thickness. As much as possible of the temporary timber lining is removed whilst the walling is being built.
When the sinking is resumed beneath the walling crib, care must be taken not to undermine the walling or brickwork. To avoid this danger, as far as possible, the sinking is carried on for a few feet narrow, in line with the inside of the crib for about 3 feet, or of the diameter of the finished size of the shaft, and then it is gradually enlarged, or widened back to its full width, thus leaving a solid foundation for the brickwork, in the form of a ledge of rock strong enough to support the first section of lining.
- Hacks or picks---for loosening the rock and chipping back the sides
- Shovels---for filling the loosened soil into the bowk or kibble
- Wedges---for forcing out the rock by driving them into the joints
- Sledges---or heavy hammers with long handles for driving in the drills, and breaking up large bits of rock
- Drills---are used to prepare holes for blasting
- Jumper---a long bar drill which may be used by a workman without a hammer
- Scraper---a tool for removing the fine dirt which collects in the hole being drilled
- Swab-stick---a deal rod sometimes used to clean out the drill hole
- Stemmers or rammers--- for tamping the borehole after it has been charged
- Cartridges---are cases containing the explosive compound to be inserted into the borehole
- Fuse---the means by which the cartridge in the borehole is fired
- Kibble, barrel, hoppit, bucket or bowk---the large iron barrel shaped receptacle for the removal of the debris or water.
As the sinking progresses new lengths of walling have to be put in, and the depth having much increased, the work has to be done from a platform, or cradle, made the same shape as the shaft, but a few inches less in diameter to permit it being raised or lowered.
The ordinary cradle is made in two parts, which are fastened together by string bolts, and strengthened underneath by bearers. It is suspended by a strong rope to which four or six bridle chains are attached by means of a large D link. This way the cradle can be raised up as the bricking advances without the men having to leave it, and it is kept from swinging or twisting by wooden wedges.
Professor Galloway has adopted an improved walling cradle which consists of two floors 10ft 6 inches held apart by corner angle irons. Using this it is possible for the sinkers to continue operations whilst the wallers are engaged above them.
Keeping the shaft vertical
To keep the sinking 'plumb', plumb lines are hung from the first crib with a weight at the end of each ; these lines, suspended at intervals of about 6 feet all round the shaft, form a good guide for the sinker, and also for fixing the next brick curb. As an additional check that the second curb is fixed exactly under the first, a centre plumb line is hung down the shaft. A heavy plumb bob at the end of this holds the line in the centre of the pit by means of a rod, called the radius rod which enables the appropriate distances to be measured.
Second section of walling
This is commenced from a bricking or walling curb which may be of wood or iron. The curbs are made in segments and fitted together in the pit so as to form a circle the exact circumference of the shaft. To get a perfectly level bed for the walling crib, a straight edge and spirit level are used. The walling is continued until it has reached within 3 feet of the wall above; some of the rock is now cut out from the ledge supporting the first section of walling, and stones or bricks are inserted in the space thus made; so connecting the two sections without any damage to the foundation of the upper part.
Water rings or garlands
In wet shafts water rings or ring cribs have to be put in to catch the water which percolates through the brickwork. These are made in the same way as walling curbs but hollowed out like a channel, or with a groove right round the shaft, forming a kind of dish. They are built into the shaft in such a way as to catch the water as it trickles down the sides of the masonry, it's then conducted by pipes into a lodge room, or into the sump.
Cost of sinking
The cost of sinking shafts frequently reaches a very large amount; £60,000, and even sometimes over £300,000, have been spent to reach a seam at a depth of 600 yards, so there is a great temptation to make one shaft suffice. But after the experience gained in the Hartley accident in 1862, by which 204 were suffocated, the Coal Mines' Regulation Act states that " there must be at least two shafts or outlets, with which every seam for the time being at work in the mine shall have a communication; such shafts must not at any point be nearer to one another than 15 yards, and there shall be between such two shafts a roadway not less than 4 feet wide and 4 feet high."
Sometimes sinking operations are interrupted by inrushes of heavy feeders of water, beds of quicksand, or loose gravel. The special methods of sinking adopted to overcome such problems are briefly described in the book but are so technical and specialised that they are referred to here just by their section titles ;
- Pile sinking
- Brick drums
- Haase process
- Poetsch freezing method
- Kind-Chaudron System
- Metal tubbing
Ventilation a sinking
As the shaft increases in depth it becomes necessary to create a means of supplying the workmen below with fresh air, and sometimes for this purpose air is forced down a pipe about 18 inches diameter; the shaft itself acting as an upcast; at other times air is drawn through a similar pipe and the shaft acts as a downcast. Sometimes the shaft itself is divided into two parts by brattice cloth with the pure air travelling down one side and returning upward on the other side.
It must be remembered that the impure gases and smoke given off by the explosive and lamps necessitate a plentiful and constant supply of air to keep the atmosphere in the shaft fit to breath.
Lighting the shaft
Various means are used to secure a good light in sinking pits. Frequently the sinkers use tallow candles, or 'comets'.
When approaching seams of coal likely to contain fire-damp, safety lamps are used.
Occasionally, electric light is installed when the shaft approaches considerable depth.
If the quantity of water met with in sinking is not very great it can be removed in the ordinary bucket or 'bowk' used to raise the debris.
If, however, the amount is more than can be dealt with in that way, specially made tanks are used to deal with the large quantities quickly. It has been found possible to deal with 20,000 gallons of water per hour from a depth of 400 yards without interruption to the sinking by means of the Galloway pneumatic tank.
Pumps and pulsometers are also employed, at Abercynon, in South Wales, over 35,000 gallons of water per hour were dealt with by means of pumps whilst sinking. For raising water up to a height of 100 yards pulsometers have been highly effective. One of these has been known to deal with as much as 30,000 gallons per hour against a head of 107 feet.
To remove the rock expeditiously, explosives of various kinds, like gunpowder, dynamite and blasting gelatine, are used. The holes for the explosive are prepared by hand or by drills driven by compressed air or electricity. The shots may be fired by means of ordinary powder or electricity.
With ordinary powder fuses there is uncertainty of burning speed, dangers of miss-fires, hanging fire, and dense smoke in wet sinkings; but with electric fuses and firing there is greater safety for the miner, fewer miss-fires, no flame, and no smoke from the fuse. Should a miss-fire occur the borehole can be approached in safety when the exploder is disconnected from the cable. A series of shots too may be fired simultaneously in safety from an electric battery at the surface, and thus a larger quantity of debris removed for the same power.
Pit bottom arrangements
In opening out the new colliery the size of the shaft pillar left, and the manner in which the roads are laid out around the pit's eye, will have an important bearing upon the future success of the workings. As not more than twnety men can be employed at any one time until the road forming the communication between the two shafts is made, this will demand the earliest attention of the engineer.
The dimensions of the pillar of coal left to support the shaft will depend greatly on local conditions, such as the depth, thickness, inclination, and nature of the seam to be worked, nature of overlying and underlying strata, position of known faults etc. If too small/large complications can arise when production starts. For instance, for any depth up to 200 yards it would be as well to have a minimum radius of the shaft pillar of 150 yards. In some cases the whole of the coal around the shaft is removed and and the space filled thoroughly with stonework.
The direction and construction of the main roads will be questions of great importance.
The first point is the relative position of the shaft to the bulk of the royalty or undertaking. Generally the pits are as near to the centre of the property as possible, but if the seams are greatly inclined, and water in large quantities is present, then it may be desirable to sink the pits at the lowest point in the property.
The cost of haulage in bringing the coal to the shaft must be considered as well as the natural drainage of water.
- The roads should be as central as possible for the whole area, in level seam
- They should drain as much water as possible
- The gradient should be in favour of the full load
- They should encounter as few faults as possible
- They should pass through as few properties as possible in view of the 'wayleaves' to be paid.
Gradient and how kept
It is very desirable that the main roads be well laid. A great deal of broken coal, and dust, as well as delays to the traffic, are caused by carelessly laid roads. Therefore the gradient of the roadway should be made uniform, with a fall of 1/4 inch to the yard , or one in 130, towards the shaft. A simple T bob and plumb line, Brown's self-indicating marker, or a clinometer, is necessary if the roadways are to be kept perfectly uniform in gradient.
The line of alignment or direction is kept with the assistance of a surveyor. [the lengthy and detailed process is fully described in the book].
Rails and sleepers
To prevent delays by trams getting off the roads at the pit bottom, the whole of the tramways should be laid in a permanent manner, with rails not less than 30 lbs to the yard; these rails should also be made of steel, flat bottomed, and afterwards fastened to steel sleepers. All the partings or junctions should be specially made to template, and the whole securely fixed and bolted together to proper gauge.
Great care must be taken in the erection of suitable arches around the pit's eye and along the main roads to prevent the crushing caused by subsidence. The whole of the coal should be removed for a few feet behind the intended walling, which may be of brick or stone, and soft debris substituted as packing, so that when the pressure sets in it will be distributed evenly over a wide area, and the side walls kept intact.
To provide room for the passage of empty or full trams by the side of the carriages, the shaft is often widened out, or ' bell-mouthed' at the bottom. This is preferable to increasing the number of roadways through the pillar.
At some collieries no horses are stabled underground, but in other cases many are taken underground, never to see the light of day again. Provision should therefore be made in the latter cases for proper stabling in the mine. They should be positioned where they can be easily ventilated by fresh air ; each stable should be large enough in deep collieries to provide for at least 25 horses and properly floored. They should also be provided with pipes for the conveyance of fresh water.
The bottom of all shafts should be well lighted to facilitate traffic and prevent unnecessary accidents. In some cases coal gas given off by the strata is taken to the surface, and after being purified, is conveyed down the shafts in pipes to be utilised for lighting purposes around the pit bottom, and along the main sidings. In other collieries electric light is used, and in a few cases naked light, as from a 'comet' is used.
In order to secure an adequate supply of air for the workmen as they proceed onward in the levels, it is necessary that the roads should be driven in pairs. By this means fresh air is carried in along one roadway, called the intake, and , after passing the workmen, is brought back to the upcast shaft by another roadway called the return. Cross cuts are made at intervals, from one road to another, and ' stoppings' erected when it is necessary to carry the air forward to the working places. Occasionally, pure air is carried on the forebreast of a level in pipes; in such a case the roadway acts as a return.
Around the pit's eye
This is a series of Don'ts, from which I conclude that the 'pit's eye' is the area immediately at the bottom of the main shaft where the cages are;
- Don't forget to prepare for falling material from trams and from the shaft sides
- Don't fail to be on the alert to prevent trams running into the sump through an accident with the shackles
- Don't allow the crowding of men towards the pit's eye at the close of the shift. Many accidents have arisen through horseplay and rashness at the pit bottom.
- Don't omit to carefully watch the winding apparatus; lest any derangement of bridle chains or safety hook should have taken place.
- Don't fail to report the slightest movement of the shaft bottom which might have caused a shifting of the guides or pump pipes.
- Don't forget to observe carefully the heaving of the roadway, or movement around the roof, which may indicate a yielding of the arches.
- Don't have the roadways about the pit bottom too narrow ; these now frequently reach a width of 24 feet and a height of 20 feet.
- Don't allow comets or other naked lights too far along the roadwys in collieries where safety lamps are necessary.
- Don't permit any accumulations of waste, oils, or grease in the engine houses.
- Don't attempt to jump on the carriage once the signal to wind up has been given.
- Don't allow any carelessness or negligence in signalling on the part of the banksman or hitcher.
- Don't forget to examine the 'sump' for gas
- Don't place improper or unsuitable staging over the sump.
- Don't fail to provide a sump large enough for any emergency which may occur owing to an accident to the pump.
- Don't rob the shaft pillar of its strength by placing boilers or engines too near the shaft.
- Don't have too great a gradient for full trams leaving the cage and too little for those entering it.
- Don't fail to properly secure the trams in the cage before signalling
- Don't permit more than the authorised number of workmen to ascend in the cage at each wind.
- Don't permit workmen to carry their working tools or gear with them in the carriage when ascending.
- ALONG THE ROADWAYS
- Don't play with the signal wires along the roadways, many accidents are traceable to this folly.
- Don't forget to keep the line of alignment well in mind.
- Don't forget to keep the roadways clean and in good order.
- Don't allow tools or other obstacles to be placed in the manholes.
- Don't place signal wires across the manholes.
- Don't permit accumulations of dust along the roadways
- Don't forget to search and prepare for rails losing gauge.
- Don't forget to sprag the trams in the best position.
- Don't neglect to use proper precautions with haulage ropes to prevent accidents.
- Don't fail to frequently examine ropes, couplings, and shackles.
- Don't omit to have the manholes sufficient in number and frequently whitewashed.
- Don't place the rollers and sheaves in improper places. The life of a haulage rope and the daily output of coal greatly depends upon a wise arrangement of pulleys and sheaves.
- Don't forget that a good code of signals is absolutely necessary on roadways, and that weak or indefinite signals often arise from weak batteries.
- Don't place sleepers under the rails at random; have a definite well-considered rule. remember a roadway well attended to will save much inconvenience and trouble as the traffic increases.
- Don't allow old timbers to stand in the main haulage road. They are liable to fall in front of a train of trams and throw it off the rails.
- Don't place air pipes or water pipes too near the rails; trams coming into contact with them often cause serious damage and delays.
- Don't attempt to pass a journey on the engine road without communicating with the 'rider'.
At the Gilfach Sinking Pit
On the 4th of November 1895, a most plucky and successful rescue was made at the Gilfach Goch sinking pit, in Glamorganshire, when that daring but cautious spirit so characteristic of true heroism exhibited itself.
On the evening of this day, two sinkers were preparing to lift the walling stage at the South Pit, which was 585 yards deep, when accidentally the stage slipped, precipitating the sinkers head foremost into the water and under it. The poor fellows, however, soon rose to the surface of the water. After a hard struggle they succeeded in reaching the chain attached to the winding rope, and to this they clung for over an hour, with cruel death staring them in the face. The dirt and lime in the water, the weight of their clothing, and the cold, caused them to feel thoroughly exhausted, and every moment they were tempted to yield their grasp of the chain to which they hung with benumbed hands.
Whilst the poor men were in such a terrible plight below, their friends on the surface were not unmindful of their duty. Rees Jenkins, a mechanic, hurriedly ran to the pit's mouth, and knowing that any moment lost might prove fatal to the poor sinkers, or make rescue more difficult, he volunteered to be lowered down the shaft by means of a hemp rope.
A code of signals was arranged. Mr Snape, the experienced manager, took command of the operations, and Jenkins gradually desecended to the abysmal depths below.
Many a secret prayer was offered for his safety, and for the success of his perilous venture.
Slowly, inch by inch, foot after foot, and yard after yard the rope was let out from the windlass. The suspense was intense. Anxious workmen stretched over the timber barricades and strained their eyes in trying to penetrate the deep gloom of the shaft. A painful silence had reigned for some moments, and the sturdy sons of toil felt a thumping of the heart as they conjectured what a moment might bring forth.
Hush ! a signal is received from below. The men at the windlass are ordered to stop and hold firm. Jenkins had reached a point where he could see the two sinkers clinging to their awkward support. Thoughtfully, he signalled to those above to stop his descent, lest on reaching the men he would be seized by them and overcome, owing to their eagerness to escape from their watery tomb.
Sighs of relief, and tears of joy come from the horny handed workmen at the shaft's mouth. The signal has been given. The two sinkers are alive. Muscles are braced for a further effort, steps are alert, and there is a strange wild eagerness: every man seems ready and anxious to do something.
Meanwhile the cries and appeals of the two sinkers were pitiful in the extreme; but, assuring them that rescue was now only a question of care and caution, Jenkins signalled again to those on top 'Lower a little' and down he descended into the water beside the exhausted sinkers. Partly supporting himself on a floating piece of timber, he fastened a second rope [which had now been let down] securely round one of the men, and gave the signal 'Wind up gently'. he himself stayed below to support the second man until the rope returned.
After what seemed an age to the two men whose limbs were becoming benumbed in the water, the descending rope conveyed the message that their companion, after a trying experience, had been landed in safety at the pit bank.
Without a second's loss of time the rope was fastened by Jenkins around the second sinker, and , after a most pathetic farewell, he was gently hoisted by the willing hands above.
A few moments delay and the rope once more descended. Those above at the winch were now anxious as to the condition of the gallant rescuer. Very properly they surmised that his awkward descent by the rope, and his long stay in the water, had made his state critical. He must be weakened, and blinded by the floating lime and debris in the water, and they eagerly awaited his signal to wind up.
Ultimately it came. Round after round of the rope was brought in and coiled; but unexpectedly there came a sudden, and unaccountable, strain at the rope, which those at the windlass could not understand. An accident must have occurred, and on careful examination it transpired that by the swaying of the rope in the shaft, it had become entangled with its precious burden in the signal wires and electric cable.
Fears were entertained as to the effect, but without a moment's loss a second rope was let down. With great care, and singular daring, Jenkins, now dangling in mid air, fastened this further frail support round his body. Guiding and steadying himself with his hands and feet, he once more signalled 'Wind up', and in a few seconds, bruised and exhausted, and smarting from the effects of the lime-water which had penetrated into the cuts made into his flesh by the rope and shaft sides, he was successfully landed amidst the cheers of his mates and the heartfelt rejoicings of the rescued men and their friends.
Methods of working coal
After deciding upon the general form in which the colliery is to be opened out, we have to consider the best mode of working away the coal. In the older collieries a simple and natural method was possible, and generally adopted. It consisted in opening ranges of working places, each as wide as the nature of the floor and roof would admit of with safety, and each divided from its neighbour by masses of coal braod enough to sustain the pressure from above. This constituted the first stages of the system of working now known as post and stall, bord and pillar, and stoop and room.
Pillar and stall
Or post and stall, is mostly practised in the northern collieries of England. By this plan the seam is cut up into square or oblong pillars, varying in size according to the thickness of the seam, tenderness of the coal, position of the workings beneath the sea, or important buildings at the surface.
A pair of main levels or roadways are driven from the pit towards the boundary, connected to each other by narrow roadways, slits or cross cuts for ventilation. From these main levels, roadways are again driven out at right angles about 60/200 yards apart. From these ' endings' or roads, ' bords' are driven out, and from these ' bord stalls' are started at distances varying from 10-30 yards apart. It will be seen that the coal is thus removed in two operations; first, stall roads are driven and pillars formed; second, pillars are removed by a second process.
In the early history of mining, these blocks or pillars were left unworked to prevent subsidences, but now they are removed in various ways by dividing them into two, four, or small pillars, called 'juds', by roads passing through in different directions, or by a series of drivages, or slices along the sides called ' jenkins', or along the ends called ' skirtings'.
This operation of removing or working the pillar is by far the most dangerous part of the work, and is carried on only by the most experienced of the workmen.
In the actual coal cutting the first operation generally consists in ' holing', ' kirving', or ' undercutting' the seam--i.e either the lower part of the seam is cut away with a pick, or sometimes coal cutting machine; or, if a soft layer exists under the seam, undercutting is performed in it, with the object of reducing waste, since holing causes so much waste.
The width of the undercutting is equal to the width of the road, but its depth depends entirely upon the nature of the seam; strong coals require deeper undercutting than tender or weak ones.
The coal undercut is now got down by cutting a vertical groove along one side, and then breaking down the remainder either by blasting or wedging.
Thrust and creep
Thrust and creep are caused by pillars of insufficient size to support the roof or keep down the floor being left. When the floor or roof consist of strong unyielding rock, and the pillar of coal left is too small to support the pressure thrown upon it, the pillars crack, break up into portions from which large slabs break off, and finally are crushed into small coal and dust.
When, on the contrary, the rock comprising the floor, or both the floor and the roof, is weak and soft, and the pillar of coal is too small, the downward pressure on the latter causes the floor to rise in the excavations, while the roof, if also of a yielding nature, sinks at the unsupported points. Once the creep sets in, it spreads slowly but surely over the whole district. No timbering can retard its progress; the airways become blocked up, and the district frequently has to be abandoned, and thousands of tons of valuable coal are thus lost.
Long wall, or wide work, may be stated to be a system of mining in which the whole of the seam is removed in one working. By this method faces of considerable width, from 60 to 1000 yards, can be opened out and worked along the whole distance, either in one long lift or in short steps, according to the nature of the coal, roof and floor. The roof along the face is supported by ' pack walls' and the goaf through which the roads run.
As soon as the shaft pillar has been left, roads are opened out to the right and left about 80 to 100 yards apart; from these ' heading' roads stall roads are driven, so as to keep the stalls in ordinary Long Wall from 30 to 60 feet long. By means of these roads the whole of the coal is worked away. The debris made in working is mostly stowed to form a goaf, which, with the strong pack walls built of the rock obtained, supports the roof.
The face is usually carried in one continuous straight line, but where the seam is highly inclined, or accompanied by a weak roof, it is sometimes considered advisable to move forward the line of face in steps.
There are two kinds of Long Wall, namely , Long Wall Advancing, where the whole of the coal is worked away from the shaft onward, and Long Wall Retreating, or working back from the boundary.
Theer are modifications of the Long Wall system. In the 'Nottingham' or 'Barry' plan the stalls are much wider than in the ordinary type of Long Wall adopted in South Wales.
Advantages of Long Wall
Among the advantages claimed are;
- More complete extraction of coal
- A larger % of round coal
- Easier and better ventilation
- Safer for workmen
- More men can be set to work in a given length of the face than in pillar and stall
- Simplicity of workings and fewer roads to keep open.
- Less injury to overlying seams by subsidences
Points to be observed in Long Wall
Points requiring attention for it to work successfully;
- All working places should be kept moving forward regularly; if some places fall behind, the coal gets crushed, ventilation is interfered with, and the coal becomes harder to cut.
- The line of face should be kept straight
- The working places should be carefully timbered
- The 'holing' or undercutting should be carefully spragged
- The goaves should be tightly packed and kept near the face
- The distances between the stalls should not be too short or the roads will be unnecessarily multiplied
- A good height should be kept in the roadways so as to permit a large tram to be used
- The coal should be removed completely from all parts except around the shaft
Sometimes coal seams are very thick, reaching to as many as 12 yards; at other times they are highly inclined, dipping one foor in every two; under these conditions special means are adopted for extracting the coal without unnecessary waste or increased danger to the workmen. In most cases the plans adopted are modifications of the Long Wall or Pillar and Stall methods.
The Roadways of a mine
A great advance has been made in engineering skill as applied to underground haulage during recent years. One of the simplest, and no doubt oldest, methods of bringing out the coal from the working places in the mine was the one by means of baskets, which were carried on the backs of women and children from the coal face to the pit's eye, and thence, by means of ladders, it was taken up through the shaft to the surface.
Then sledges drawn by boys and girls were introduced, and these were in time followed by barrows , and these again in a few years gave place to carts or trams, which were pushed along a line of planks by women, who thus did the work of horses.
Gradually trams or tubs running on rails were introduced, and today these trams are joined together to form a train, or journey carrying many tons of coal, and drawn along by engines driven by electricity, compressed air, steam.
In some large collieries it is not unusual to find as many as twenty of these stationary engines fixed near the roadways; in other cases locomotives driven by electricity travel along the line of underground rails, and bring out long trains of loaded tubs.
Systems of underground haulage
The systems may be divided into four classes;
- Direct haulage by single rope
- Main and tail system of rope haulage
- Endless chain or rop
- Railways worked by electricity or compressed air.
The empty and full trams are frequently taken to, and removed from, the working places of the colliers by young men called putters or trammers. When ready for removal to the main roads, they are taken by horses, which sometimes take them to the shaft bottom, but generally to a siding within reach of a haulage rope worked by an engine.
Direct system of haulage
In this system only one line of rails is necessary; one end of the rope is attached to the engine by means of a drum, and the other is connected to the front part of the tub. Bridle chains or backstays may be used to prevent accidents.
Main and tail system
This adopted where the roadway is uneven, or not sufficiently steep for the empty trams to run back into the workings. In this case a Tail rope is used, and is generally attached to an engine near the shaft, or top of the roadway ; but is taken over pulleys fixed at one side of the road, and properly guided at the curves. Thus the main rope which lies in the middle of the road upon horizontal rollers draws the full trams outwards and the tail rope takes the empty set inward.
Endless rope haulage
The principle of the endless rope and the endless chain systems are the same, the difference in their application is only that of detail. In the endless rope method a rope passes either above or below waggons, and travels continuously in the same direction. It passes over a drum or round clip pulley at each terminus and thus receives the motion which is communicated to the trams in the train. Two sets of rails considered necessary.
Signalling on roadways
To communicate definite and distinct messages from one end of a haulage road to another which may be more than a mile distant in the mine, a good system of signalling is necessary. Satisfactory results have been obtained by adopting two galvanised iron wires and stretching them tightly on small insulators ; they should be about 6 inches apart, and placed on the opposite sides to the refuge places arranged for the workmen. Signals may then be sent to the engine house from the further end of the haulage plane by a small ringing key, or from any points in the plane by the rider, or person in charge of the train of trams, pressing or rubbing the wires together with his finger, or short iron pin. By this means a bell in the engine house is rung, and the haulage rope can be stopped or started at any point.
There is a printed code of signals arranged by the manager of the mine.
There is a great variety in the shape, size, and construction of underground waggons or trams. They carry a load in some coal fields amounting to 2 tons, in other districts , where the seams are thin, they carry only 8cwt.
They may be built of iron, steel or wood, and weigh from a quarter to half the load they carry. Iron or steel trams are now generally adopted where the loads are heavy and the travelling rapid; wooden trams, however, being easy to repair, and costing little to make, are extensively used too.
The wheels tange from 10 to 18 inches in diameter and are made of cast iron, cast steel or forged steel. The rails are made in lengths ranging from 6 to 18 feet, and they are laid on transverse supports called sleepers, the latter made pf wood, iron or steel.
Transmission of power
Haulage engines may be placed;
- In the mine, where the steam may also be generated
- The engines may be placed in the mine, and the steam generated at the surface conveyed down the shaft to them in pipes
- The haulage engines may be placed at the surface with the boilers, and ropes taken down the shaft to the tubs
Where compressed air or electricity is used to drive the engines, the power is taken into the mine by means of pipes or cables
Rules for colliers
The British Parliament has at different times passed many Acts for the protection of the miner. It is the duty of the workman to make himself thoroughly acquainted with these rules, both ' general' and 'special', as authorised by Parliament. If all underground officials and workmen adhered strictly to the regulations framed for their safety, the number of accidents in our mines would be still further reduced.
In 1851 the number of deaths in mines was 4.5 per 1000 persons employed, in 1873 it was 2.4, and in 1901 the proportion was further reduced to 1.4 per 1000.
Amongst the rules which should be attended to by colliers are the following;
- Except for a proper purpose, no person shall go into any other than his working place, under any pretence whatsoever, and in no case shall he go into old workings except by order of an officer of the district.
- He shall not pass through or beyond any cross timbers put thus -X, which, in all cases means danger, without leave or order of the Fireman, or other superior officer.
- He shall on first entering his working place satisfy himself that it has been examined and found safe, by observing whether the date has been marked with chalk on the face of his working place, and if it has not, he shall not commence to work therein, but shall return immediately to the Lamp Station, and report to the Fireman and to a superior officer, and wait directions from one of them before returning to his working place.
- He shall strictly observe the directions of the Overman and Fireman, so as to ensure the safety of his working place, and shall at the commencement of each shift, before he begins to work therein, and at proper intervals during his shift while working therein, carefully examine the face, roof, and sides of his working place to satisfy himself that the same is safe.
- If upon any such examination by a collier of his working place, any danger, want of repair, or unsafeness is found, he shall cease all operations therein until such danger is removed, or such want of repair or unsafeness is made good ; and he shall immediately proceed to remove such danger, and make such repair good.
- He shall keep his working place safe for working therein, set all timber necessary, and place such props and sprags as are necessary
- He shall take care to leave his working place at the close of every day's work in good order, and in a condition fit to be able to resume his labour therein in safety
- He must on no account leave in his working place any rubbish, small coal, or slack, which shall prevent access to the face of the coal, or interrupt the free ventilation to the face of his working place. And he shall constantly maintain a freee opening for the purpose of ventilation between the waste or gob, and the face of the coal and rib in his working place
- Every person receiving a lamp from a Fireman or other person appointed for the purpose, after it is securely locked in his presence carefully, shall examine the lamp to see that it is clean and in proper repair and is properly locked
- No person to whom a safety lamp is entrusted, or who has charge or possession of one, shall interfere in any way whatever with it, beyond the necessary trimming of the wick by the pricker, except to put it out
- Every person shall be careful so to hang his lamp as to avoid risk of it being struck by a tool
- No shot shall be fired except by the shotman
How a mine is lighted
The work of the miner is carried on amidst such dangerous surroundings, that a good light is absolutely necessary. But, up to comparatively recent times, the light supplied was indifferent, and many accidents resulted.
The earliest method of lighting was by means of torches, and when the air of the mine became too dangerous for this plan, the workings were abandoned, and a new shaft was sunk.
Tallow candles and other naked lights are used where there is no danger from fire-damp. The candles are usually carried by the miner in a lump of clay, which forms a convenient support on the floor of the mine or a heap of debris. Special candle holders are these days made in such form to enable the miner to drive the point into the timber or crevice in the rock.
Various forms of lamps, too, are in use where fire-damp is not expected. In some mines the collier has a simple oil lamp, which he places in a loop in his cap or hat, so that his hands are left free to use his pick or shovel.
As the number of men engaged in out coal mines increased, the number of deaths resulting from explosions of fire-damp became so high that the attention of Parliament and the foremost engineers and scientists was drawn to the desirability of supplying the miner with a light which would enable him to carry on his work without the great risks to which he was then submitted.
About 1815 Sir Humphry Davy, Doctor Clanny, and Mr George Stephenson, after many months of tedious work, and careful experiments, placed before engineers lamps of an entirely new design, calculated to so act even in the presence of large quantities of the deadly fire-damp, as to enable the miner to escape in safety, and for this reason the lamps gradually became known as 'Safety Lamps'.
Davy found that a very high temperature, 1,202 degrees F, was necessary to bring about an explosion; mere red heat was not sufficient, even when the gas was at its most explosive point ; and it was possible to cool down the flame below the temperature required in order that combination should take place. Common iron-wire gauze such as Davy used in his lamp would not pass flame with the slow ventilating current then circulating in the mines. The iron wire radiated or gave off the heat it received so quickly that it remained tolerably cool itself, so cool in fact, as to prevent the ignited mixture on the inside passing to the gaseous mixture on the outside, at a temperature high enough to explode it.
There are technical differences between the Davy, Stephenson and Clanny lamps [fully examined in the book].
Other lamps in use in 1901 , [and mentioned in the book], include Mueseler, Marsaut, Morgan, Evan Thomas's No 7, Cambrian. Protector, Deflector, Hepplewhite Gray, and Ackroyd & Best.
The book also contains a list of 'Don'ts' in using Safety Lamps.
A battle with hunger and thirst
Not extracted, describes an mining incident in 1899 in Pennsylvania
How a mine is ventilated
The underground workings of all mines are being constantly contaminated by the gases given off by the strata, the burning of lamps or candles, the breathing of men and animals, the absorption of oxygen from the air by chemical agencies, decaying timber, and blasting, so that a regular supply of pure air is necessary to enable the miners to work in safety.
The air in our mines becomes quickly polluted, so that engineers have for many years made a study of the best means of removing this foul air, and of providing instead a regular current of pure air from the outside atmosphere to take its place.After careful experiments they are able to estimate approximately the number of cubic feet of air required per man per minute, to keep the mine in a safe and healthy condition.
As no two mines are identical in the area of old workings they contain, the quantity of gas driven off by the strata, and other circumstances, it is unwise to lay down any law as to the exact quantity of air absolutely necessary to properly ventilate a mine. The Coal Mines Regulation Act does lay down in the first general rule the principle of ventilation adequacy, and that the quantity of air passing shall be measured and logged at least once a month.
In many large collieries as much as 350,000 cu ft per minute of air are made to circulate; this would equal about 250 cu ft per minute per man and 750 cu ft per minute for every horse engaged underground.
How a ventilating current is produced
A current has to be produced that will pass through ALL the roadways and working places in a mine where men are engaged, lights are used and impurities given off by the strata.
To secure this current, there must be two entrances to the mine, one for the pure ingoing air, called the ' downcast', and the other, for the return, polluted air, called the ' upcast'. These shafts , or openings, are connected by means of roadways called the intake and return roadways. In the roadways there are doors, regulators, air crossings and brattice sheets or pipes, to assist forward the air to the working places, and to apportion properly the quantity passing to the separate districts. To connect these roadways as they are driven forward, cross cuts are made.
The air current is sometimes produced by placing a ventilating machine, called a compressor, or forcer fan at the top of the downcast shaft. Generally, however, the more convenient plan of placing an exhaust fan at the top of the upcast is adopted. This acts in a contrary manner to the forcer fan, and draws, exhausts, or 'sweeps out' the air at the top of the upcast, so that there is a continual pressing forward of the air in the mine to the shaft, and a current is thus established.
Sometimes too, a furnace, safely guarded from the explosive gases of the mine, is placed at the bottom of the upcast. The air in the shaft is thus heated and rarefied to such an extent, as to make the difference of pressure between the column of air in the downcast and upcast sufficient to produce a strong ventilating current which will pass into and through all the working places of the mine.
The three alternative ways of producing adequate ventilation are thus;
- Expansion of the air in the upcast by means of a furnace or steam jet
- Compression in the downcast by a waterfall, trompe, or compressor fan
- Partial vacuum of the air in the upcast by means of an exhaust fan
Coursing the air
The mere fact of sending into the mine a sufficient quantity of air to dilute the carburetted hydrogen, carbon dioxide, or other gases present, does not alone suffice to prevent accumulation of gases. The air current must also be directed to all the parts where gas is disengaged, or men employed, great care being taken also to avoid its direct passage by short cuts from the downcast to the upcast. This is the most important point in mine ventilation, and one frequently neglected.
Natural inertia and friction mean the air will soon come to rest unless greater pressure is applied to it on one side than the other. It is necessary therefore that roadways should be as large, smooth, straight and short as practically possible. The air current should also be split.
In the earlier days of mining, air splitting was unknown, and when it reached the last body of workmen in the extremities of the mine it was thoroughly foul and unfit for breathing or the dilution of gases. Now, however, engineers split the air into several different currents, allotting a quantity for each district according to its requirements. By this method the gases and impurities aren't carried from one district to another; also in the event of an accident in one district the air supply to the other districts is not cut off.
For many years mines were only ventilated by natural means, and the direction of the air current changed with the seasons, and sometimes with the change from day to night. As the current became sluggish, a flaming lamp or grate of fire was suspended by means of chains near the top of the upcast. Gradually these plans developed into huge furnaces placed at the bottom of the upcast. Whilst these furnaces were capable of producing very large volumes of air, because of the dangers they also introduced they were gradually replaced by safer means and now ventilation is almost invariably produced by fans.
When these fans are used the top of one of the shafts is covered over, and a drift terminating in a chimney, or at the blades of the revolving vanes of the fan, is made. The majority of ventilators at present in use are the centrifugal type. [The book has a detailed technical description of this type here].
Four of the best known fans in this country are the Guibal, Waddle, Schiele and Capell.[the book now has detailed comments on each of these]
The gases of coal mines
Mines yield different gases varying considerably in their nature, and the extent of the danger they introduce. They include the following ;
- Carburetted hydrogen [CH]---Fire damp or marsh gas
- Carbon dioxide [CO2]---Choke damp or black damp
- Sulphuretted hydrogen [SH2]
- Carbon monoxide [CO]---white damp
Is produced naturally and may be found sometimes in damp marshy ground bubbling up through the water of stagnant pools, where decayed vegetation rests at the botom, where it can be set on fire and called marsh gas. It is given off more or less abundently in all coal mines, although absent in some shallow mines where it drains to the surface through the strata. It is lighter than air and is found lodging near the roofs of mines , and in old workings where the quantity of air passing is limited. It is found in the pores or cells of the coal, and frequently bursts out in the form of blowers into the workings or roadways. It then cases great damage and makes the air in the mine very explosive. It is a very light, colourless and tasteless gas and can be reduced to a liquid when subject to pressure or cold. In its pure state it will neither burn or explode, neither will it support combustion or light, nor the respiration of men and animals. To burn or support combustion or respiration it must be mixed with certain proportions of air, it will then burn with a slightly luminous flame.
Its explosive properties depend on the proportion of air present and it exhibits different properties according to the amount of air mixed with it.[The book now has a chart showing the behaviour of differing air mixes].
It is given off from the coal faces, roof, floor, and sides of working places and roadways, and from old workings. Commonly found near faults or changes in the nature of the strata or the coal. It is understood that an increased amount of fire damp can be given off after a fall of the barometer.
The fire damp of mines is often diluted with other gases which have a string odour, so that experienced workmen conclude that it can be detected by its smell. The plan almost universally adopted to search for fire damp is to take a safety lamp of the Davy type and utilise its flame in the examination of the air to be tested. [the nature of this test is described in the book].
Is known as carbonic oxide, its chemical symbol is CO, its presence in mines is much less frequent than that of black damp but it is far more poisonous and treacherous than that gas. As little as half a percent in the air of the mine produces giddiness and faintness while over 1% may cause death. Even one tenth of 1% if breathed for some time may prove fatal. It is known by its sweet and delicate odour. Candles burn well in this gas so that explorers have no guide as to its presence. There are examples of canaries and mice being taken down mines to help warn of the presence of this gas.
Or carbonic acid gas is known amongst miners as choke-damp, black damp and stythe. It has no colour, smell, or taste, neither does it burn or support combustion. It is formed in mines by the decay of organic matter, by the exhalations of men and animals, the burning of lamps, and blasting operations. It is an extremely heavy gas, about 1 1/2 times heavier than air, and for this reason is found in the lower part of the roadways, swamps and dip workings. It is removed by the circulation of brisk currents of air. It should always be suspected at the bottom of old wells, shafts and sumps. Lights quickly become extinguished in this gas and its presence can thus be easily detected.
Produced in mines by the decomposition of iron pyrites in damp or wet workings.Generally accumulates in old workings which contain water and is recognised by its disagreeable odour. It is never found in large quantities in coal mines. When breathed in small quantities it is fatal.
Causes and prevention of accidents in mines
Colliery accidents are attributed to a variety of causes and are not limited to the effects of fire damp and the other mine gases. In the year 1902, no less than 452 men lost their lives in our mines owing to falls of roof; 52 were lost and 385 persons injured, too, in the same year, whilst using explosives ; explosions of fire damp caused the death of 231 persons on an average each year, from 1851 to 1855, but the average for the five years ending 1901 was reduced to 64.
Practically 50% of the lives lost in mines are the result of falls of ground, principally along the working face, when the collier is engaged in hewing coal, and to a smaller extent along the haulage or ventilating roadways; 30% are due to miscellaneous causes, such as breakage of ropes and shackles, irruption of water, and accidents in shafts. Less than 2% are due to explosions of fire damp.
To reduce the number of accidents from falls of roof and sides, stringent rules have been framed by those responsible for carrying out the requirements of the Coal Mines Regulation Act, and they should be strictly obeyed. The following points too should be carefully attended to;
- Since many lives are lost owing to delay in setting suitable timber, all posts, sprags etc found necessary should be erected immediately they are required
- The timber should be set at the best angle to withstand pressure
- Posts and sprags should be stamped into the ground to prevent slipping
- The lines of 'slips' or cleavages in the roof should be examined, and provision made for them before placing 'lids'
- A post should increase in thickness proportionate to its length, and a small post with a lid should be used, rather than a post so strong that it would force its way through the weak top
- Timber should not necessarily be 'notched' and so weakened or buried in goaves
- Collars should not be too long, and all lagging arranged so as to protect the weakest part
- All empty places behind the lagging should be carefully filled
- No timber should be withdrawn until the surrounding strata has been carefully examined
- Since the majority of accidents occur in places where the top is supposed to be safe and strong, great caution should be used before exposed surfaces are left unprotected
Explosions of fire damp
Some of idea of the state of a gaseous colliery at the beginning of the last century must be conceived , ere progress made in mine ventilation can be understood. Such condition is well conveyed by an authentic account of what the famous John Buddle was accustomed to to at Wallsend Colliery. This account is related by the principal performer, one Anthony Sharp. The scientific and humanitarian interest which was beginning to be awakened in connection with coal mine explosions, and Mr Buddle's reputation, brought to Wallsend many visitors of various degrees, from Russian Czars downwards. Not far from the bottom of the shaft, Mr Buddle had prepared an opening of considerable height and size, where gas was nearly always found lurking next to the roof. This chamber served as a laboratory for the practical demonstration of a pit explosion on a small scale, as described in a local newspaper. The modus operandi was as follows;
When a party had arrived, Mt Buddle would say, "Now Anty, dis thoo think thoo can give us a crack the day ?"
"Wey, aa'll try" was Anty's usual reply.
After getting 'Belaw' with infinite care, at the proper time, Anty would go forward a little into the chamber already described, with a lighted tarry rope-end in his hand, Mr Buddle and his visitors following. At the proper place, swinging his extemporised torch around his head, he would throw it up as high as possible, and then, flinging himself flat on his face , would there await results.
The explosion almost invariably occurred, sometimes with greater force than even Mr Buddle bargained for, and as its noise echoed and re-echoed through the workings, the party generally concluded that they had had enough of coal mining for that day at least, and were glad to be hauled up the shaft again to fresh air and safety.
As recently as 65 years ago the condition of a large fiery mine in the same district must have been deplorable. On the day previous to a great explosion near Wallsend in 1835, whereby 102 persons lost their lives, the pit was in so dangerous a condition that a heaver named John Bell and five men working with him were obliged to come away extinguishing their Davy lamps, which had already become red hot , whilst doing so. On the morning of the explosion, before Bell left work in the forenoon, all the six Davys were on fire.
The explosion of fire damp may be caused in a variety of ways ; the most frequent being by a naked light coming into contact with the gas when it is at an explosive point; the naked light may be from a defective lamp gauze, an open lamp, a 'blown-out' shot, a fall of hard stone from the roof, or sparks given off from a pick striking a stone or iron pyrites.
Blasting, or shot firing, produces a double effect, favouring the propagation to a distance of a fire damp explosion. It puts into motion the fire damp collected in the cavities, and draws it also from the goaves, until it is brought into contact with the flame, and ignited amidst a cloud of dust blown into the air by the violence of the blast.
Coal dust propagates and intensifies the effects of a fire damp explosion, and when the flame is accompanied by a violent rush of air, may even originate an explosion, in the absence of the accumulations of gas in such quantities as are necessary before they can be seen on a safety lamp flame.
The use of explosives in mines is hemmed in by many restrictions, all calculated to diminish the risks involved. In all coal mines in which inflammable gas has been found within the previous 3 months in such quantity as to be indicative of danger, the use of any explosive, other than permitted explosive is absolutely prohibited in the seams in which the gas has been found.
Moreover, every charge of the explosive shall be placed in a properly drilled shot-hole and shall have sufficient stemming. Every charge shall be fired by an efficient electrical apparatus or by some other means equally secure against the ignition of inflammable gas or coal dust.
Every charge shall be fired by a competant person appointed in writing for this duty by the owner, agent or manager of the mine. Many other precautionary methods in the use of explosives, the treatment of coal dust, the placing of timber etc are recommended by Government experts, but it would be well here to try and emphasise the words of Messrs Lyell and Faraday in their report on the Haswell Colliery accident. They say " We believe that if the education of the miners generally can be materially raised it will conduce to the security of the lives of the men, and the perfecting of the art of mining, more effectively than any system of Parliamentary inspection which could be devised."
Miners and gas
This section has not been extracted, it is based on an incident in 1902 at Wharncliffe Silkstone Colliery, Tankersley, near Barnsley where men wrongly continued to work after gas was detected, and a letter written by the Chief Inspector of Mines regarding this.
Fatal accidents ---1901
During 1901 there were, in mines under the Coal Mines Act, 951 separate fatal accidents, causing 1101 deaths, a decrease of 11 accidents but an increase of 89 deaths compared with 1900.
The numbers of non-fatal accidents reported during 1901 were 3747 at mines under the Coal Mines Act.
The death rate from accidents in 1901
The death rate of underground workers in mines under the Coal Mines act was 1.46 per 1000 persons employed, slightly higher than 1900 when it was 1.44 per 1000.
The proportion of deaths from different classes of accidents in mines in 1902;
- Falls of ground---44.3%
Removal of water from mines
The rocks surrounding coal seams always contain a certain amount of water, which of course has a tendency to find its way into the mine. Some of the rocks are full of cracks and fissures, which readily pass the water, and in the case of shallow mines, the least downfall of rain makes a very appreciable difference in the amount of water to be pumped. Some rocks are formed of alternating layers of permeable and impermeable strata, and on the water percolating through the surface ground, or entering strata at its outcrop, it will run through the permeable or porous layers, but will be intercepted by the impermeable or watertight strata, and there form large reservoirs or feeders of water, which when tapped either by sinking, or by the breaking of large masses of roof, which causes fracture, and displacement of the overlying strata, releases itself and floods the mine.
Sometimes the water from rivers or ponds percolates through the strata, and reaches the workings, and has to be removed out of the mine by means of pumps or adit levels.
Drainage by tunnels
Frequently mines are so placed that the water may be drained out of them by means of tunnels or adit levels as fast as it gathers, and the cost of the constant working of pumps is thus avoided. [the book goes on to give several examples of extensive tunnel/adit drainage systems throughout the world].
When tunnels or adits cannot be conveniently arranged to drain a main then the water must be raised by means of pumps or the winding machinery. Water barrels or tanks which may be attached to the cage in use for winding coal are sometimes adopted, where the quantity of water to be raised is not excessive. At other times large tanks capable of holding some 800 to 1200 gallons are used. When the latter is adopted one of the cages is removed and the tank substituted. Professor.Galloway was able to raise as much as 5000 gallons per hour from a sinking pit at Llanbradach.
At most collieries where the quantity of water to be dealt with is large, permanent pumps are found advantageous. These may be of the Lifting [Suction] or Forcer [Plunger] type. These can be su divided into single acting; double acting; horizontal; vertical; rotary; non rotary; hydraulic; or centrifugal. They may be driven by engines of the Cornish design, simple or compound, single or duplex, with differential valve gear, or with valves with the Riedler design.
Bucket or suction pumps
The bucket or suction pumps used in mines are similar in general design to those used for ordinary wells ; they are however made on a larger scale and more carefully planned. [the book now has a technical description of how one works]
Action of a forcer pump
In a suction pump we use a bucket which carries the water from the level which it reaches by atmospheric pressure ; in a forcer pump we use a ram or plunger which drives the water before it. [the book now has a technical description of how one works]
Direct-action steam pump
Owing to the difficulties experienced with the pump rods hanging in the shafts when the pumping engine is placed at the surface, it has become a common practice with mining engineers to place the pumping engines underground near the bottom of the shaft. Such pumps can be applied to lifts of many hundreds of feet as the water is always flowing in one direction.
When it is necessary to convey water from a distant part of the mine to the shaft over an intervening ridge, a siphon may be used with advantage, provided the rise in the roadway is not more than 15 to 20 feet. [the book now has a technical description of how one works].
The Flooded Mine. By Charles Wilkins.
Many years have passed since the Tynewydd catastrophe in the Rhondda Valley, but its history is as endurable as that of Alma or Balaclava, and well diserves being recounted here.
The No 3 seam of New Cymmer Pit, becoming full of water, became, by its proximity to the Tynewydd Pit, a source of danger, as the men there employed were working close to the boundary. It is stated that the day before the accident one of the Tynewydd men said that they were nearing water, and it is alleged that an approach was made so near that only a slight barrier existed in the pit between the men and an immense body of water. Suddenly, on Wednesday, April 11, 1877, this barrier is supposed to have given way just as the men were leaving work, for forth into workings came a torrent so strong and foam crested that the workers thought the sea was actually upon them, and fled for their lives. Happily most of the men had reached the surface, and only 14 remained to do battle with the resistless enemy.
Five of these escaped for a little while in one direction, and five in another, but the other four were overwhelmed and lost.
The first 5 men, led by an elderly collier named Thomas Morgan, ran into what is known as the 'rise'---workings above the ordinary level--and, the air being driven in before them by the rush and weight of the water, they found themselves, though hemmed in, yet in comparative safety.
In this condition, and knowing that a relief party would certainly try to reach them, the plied their mandrils vigorously on the sides of the stalls, until a responsive noise was made by the searchers, and then, their whereabouts being known, a strenuous effort was made by them to cut themselves out.
In one night eight yards of coal were cut through, and as the searchers worked with equal ardour they came on Thursday morning, the day after the irruption, close to one another. When only a thin barrier remained, Morgan's son, eager to get out, rushed at the place and made an opening with a chisel; but so great was the rush of compressed air , that this unfortunate young collier was taken up, just as the March wind takes a seared leaf from the ground, and hurled with immense violence against the opening. So great was the force that death was instantaneous, and some difficulty was experienced in getting the body out of the hole. The other 4 men were rescued and brought to bank.
Poor Morgan's was an awful death.In the moment of release, just as the hard fought battle had been won, struck down, battered and slain! That dead man, as he was brought to bank, was a picture on which no eye could look unmoved. The dust of labour was on that youthful head, the furrowed lines of fatigue were upon cheek and brow; even the hand that had wielded the mandril in the wild effort to escape was still clenched.
When the others had been brought up and taken home, and were sufficiently recovered to converse with their friends, one of them related a touching incident more illustrative of anything that had occurred in the ten days of anxiety, of the deep-seated religious feeling of the colliers. The incident was as follows;---
After their race for life with the torrent foaming at their feet, and threatening every moment to overwhelm them , they rushed , as stated, into the heading from which they were rescued. Then finding themselves on dry ground and seemingly safe, they, moved by a common impulse, knelt down and prayed, and then, in concert, sang a well known and much admired Welsh hymn which is translated as follows;
In the deep and mighty waters
No one there can hold my head
But my only Saviour, Jesus,
Who was slaughtered in my stead.
Friend He is in Jordan's river,
Holds above the waves my head,
With His smile I'll go rejoicing
Through the regions of the dead.
One of the colliers stated that he would believe to his dying day that the waters seemed to subside as they sang.
As soon as these men were saved, renewed efforts were made in search of the remaining 5. While a determined band of men were searching in the mine, others, rigged up pumps, and brought every effort to bear in reducing the water; and on Friday the explorers heard for the first time, knocking proceeding from Thomas Morgan's stall, where it was conjectured, and as it turned out rightly, the remaining five men were imprisoned.
The sounds of those far-off knocks, heard in the deep cave of the earth and in the watches of the night, were described by the one who first heard them as thrilling in the extreme, solemnly touching---they came like voices from the grave; yet, even as they thrilled to the very soul, they roused and inspired to renewed efforts. There was no halting then.
The officials, having a thorough knowledge of the whole mine and the exact position of the place where the men were, it was soon seen by measurement of the place that 38 yards of solid coal intervened between the men and the explorers, and in the other direction access was completely cut off by so vast a body of water that it was not inaptly called an underground ocean.
To drain this away in time, or cut away the great barrier of coal which lay between-which should it be ? In this dilemma it was decided to obtain the aid of experienced divers, and on Saturday Frank Davies and Thomas Purvis, from the firm of Siebe and Gorman, London, came down, accompanied by Garnish, David Adams, and his son James Adams, and descended the workings.
The distance to be traversed was 257 yards, the drift was full of water to the roof, and the peril of the adventure was beyond question. The preparations in the subterranean world, on the edge of the black flowing water, which seemed to sway about as if rejoicing over its triumphs and the captives it held in its grim embrace, were such as no one had ever seen before. Even the experienced diver who first entered the water appeared to have a misgiving of the result, for he said to one standing near: -
'Did you know George Smith, the Assyrian explorer ? ' adding, '1 dived with him just before his last expedition.'
The tone was ominous, but, closing his helmet, the brave fellow waded away and disappeared.
He was followed by the second diver, and the most intense anxiety was caused as the man who held the line called out at intervals, 'Fifty feet,' 'Eighty feet', 'One hundred feet,' 'Two hundred feet.'
Every cry awoke a responsive echo from the hearts of the lookers-on, and when 'Five hundred feet' was called and this was known to be within 250 feet of the stall where the five colliers were, men looked at one another rejoicing, and already began to anticipate the recovery of the lot.
But then a dead silence ; the line was no Ionger paid out, and after a brief interval the man in charge disheartened all by saying 'They are coming back.' The trial was then a failure, and blank dismay settled on every visage.
Soon a bubbling and hissing noise was heard in the distance, and first one diver appeared and then another and Frank, coming to the surface, and taking off his helmet, after he had stumbled exhausted to the ground said;
'We have done our best, and 1 am very sorry we have been unsuccessful. We found it was impossible to get on further owing to pieces of wood in the water, the broken road, mud, and the strength of the swell.'
Still, unsuccessful as the effort was, no praise could be too great for the daring exhibited. Men applauded even as they sorrowed.
After the failure of the divers, it was seen that two courses were imperative-to put all possible powers to work the pumps, of which several effective ones were at hand ; and also at the same time to cut through to the men.
Pumping, which had been suspended, was at once renewed, and shifts of colliers were arranged to drive a heading to the imprisoned men. By Monday the water had been reduced in the centre heading, the gob was cleared, and at a distance of 22 feet from the roadway the all-important work of cutting was begun. The rate of cutting was nearly 2 1/2 feet per hour; four men worked in each shift, and changed every three or four hours. The spectacle of the first attack on the black face of the coal tomb was in the highest degree exciting. The place sloped downwards about 4 inches per yard, and every piece of coal struck away had to be pulled up and placed on one side.
As if assaulting a stoutly defended breach, the colliers advanced and plied their mandrils as they had never plied them before. They rained down blow after blow, unremittingly: no halt, no looking back, no word. Fiercely, and almost savagely, the men worked,and when the shift of three hours had passed, only fell back exhaustedfor fresh men to advance again, and show that the great, grand stimulus inspired them, prompting to the same desperate hardihood and determination.
Monday night saw a considerable amount of work done, but night and day the assault was continued.
Early on Wednesday the progress made had been so great, and the tapping of the entombed colliers became so distinct that an effort was made to elicit an answering shout. This was tried, and effectually.
Far away, still faint, yet distinct, came the halloo, and had a spur been needed, or had greater efforts been possible, this cry, which had in it more of a wail of despair than a tone of rejoicing, would have been sufficient. For, be it remembered, there were old and experienced colliers amongst the imprisoned, and these knew only too well that the nearer the rescuers came the greater would be the danger for both.
Sixteen feet head of water ever menacing them, and giving a pressure equal to 7 lbs. to the square inch above atmospheric pressure, demanded the utmost care on the part of the rescuers, who, working in a hole that, at it,, highest part, was only 3 feet, might any moment, for all they knew, with one blow of the mandril from the hand, let loose a power that would sweep captives and rescuers to destruction.
While the work of cutting out was going on, directed by the ablest, coalowners and mining agents of the Valley, no abatement took place in other efforts, such as pumping and in providing for the final moment of delivery.
By Wednesday night, 32 yards out of 38 had been cut through, and only 6 yards remained between the colliers and freedom. Then their cries became still more distinctly heard, and some of the working colliers were able to distinguish the shout of one of the entombed above the rest. A boring apparatus was now brought into action, in the first place to try to get a communication between the men if possible, to supply them with food, and in the third place to test the air.
Although the contrivance for sending in the food was exceedingly ingenious, it failed ; for the moment an opening had been made the rush of air was so terrific that it was found necessary to plug the hole. Through the opening, too, it was believed, by crevices caused in the boring, another great danger was introduced ; for there came ominous signs of fire-damp, and the pressure of the air was found to be so great that the gauze of the Davy lamp became no protection.
The colliers then faltered. Again the plug was blown out, and through the opening the gas came steadily, and the roar of the air was such as to prevent the sounds of the voice being heard except at its highest pitch. It was then, and then only, during the whole of that struggle, the rescuers fell back.
And it was now no ordinary peril. Just behind that yard or two of coal, lurking as it were, in the very dungeon where lay the five men, was a power which would have completely destroyed the rescuers. They were literally at the side of a mine which at any moment might explode and hurl every soul there present into eternity. It was no wonder, then, they faltered.
But the heroic colliers had only shown that there was a limit to human endurance : that tottering back was like to that of the strongman in the fight who momentarily falters only to rush onward and overwhelm. And so it was in this case. An old collier dashed forward, and was followed by others, and the work of cutting through went steadily on. And, be it remembered and noted that these men were not working in a place where there was ample head-room. The passage they had cut was in many places not 3 feet high and at the highest point only 4 feet.
For days, lacking food and sleep, struggling with gas heated and coal-laden air in their efforts to get these five colliers away, worked coalowners, agents and colliers in supreme disregard of their social position in life. It was a spectacle more grand in its sublime and unseen heroism than that great Crimean battle charge which makes one proud to be a Briton.
But it was at half-past 6 that even these gallant men faltered---ay, and for the moment fled. The colliers were working steadily, the doors were up, when the indications of gas became too strong to be resisted: the flames were actually bursting out through the gauzes of the lamps ; the ominous signs were everywhere visible ; another moment, and one of the direst catastrophies ever related would have had to be told.
'For your lives, fly ! By heavens the gas is upon us ! '
And round as by instinct, moving as one man, they turned and dashed up the heading into the clearer and safer places where others stood. But, like the faltering of the colliers, their retreat was only for an instant.
Back they went in the dark, groping, tumbling over one another, until brattices and doors had been re-arranged and the gas cleared, and then into the Jaws, again, of death dashed-
Less than one hundred.
Most wonderful were the endurance and action of the colliers. It was a noticeable feature that beating against this black face of coal, which at any moment might open out and destroy them, they never turned their heads. With blood streaming, in the earlier part of the week from their hands, yet they rained blow after blow, and, said a looker-on, never turned or paused.
At one time it was thought imperatively necessary to stop the pumping, for the water flowed over the bars of the flue and put out the fires, and for a brief time the pumping was stopped. Had this been continued, nothing could have saved the five colliers : but soon the pumps were at work again, and the decline of the water on Friday at the rate of 2 vertical inches per hour was watched with extreme interest.
One of the most critical parts of the rescue was the blowing out of the plug. The roar is described as hideous; no other sound could be heard---men looked blankly at one another until a pitiable voice, at its highest tension, begged that the plug should be replaced.
'The water is coming up fast ; we shall drown,' was the cry.
Another scarcely less thrilling incident was that when hope had been given up amongst the captives, and one -George Jenkins - stepped away from the little desponding group, and, without light or anything to guide him groped out of the stall into the dark water, floundering, still pressing on, until the water, getting deeper and deeper, he found himself up to his armpits, and then, sorrowfully, the brave fellow groped his way back again to his comrades, then and only then resolved to die.
'Had we,' said a leading engineer, 'attempted to break through on Thursday we should have lost every man.' It was science and valour which saved them ; science which guided the measurements, the levels, the accurate estimates ; science which counselled the doors, the brattice, the test for gas, which prompted the exertions at the pumps: and valour which nerved the arms of the rescuers, which bade fatigue flee, which ignored the craving for food, and prompted to deeds of daring unsurpassed by anything in the long mining annals of our country
When the breach was made on the eventful Friday, the man whose pick first entered was hurled back, and, for a moment there. was terrible excitement : but the precautions taken to allow the compressed air and the gas to escape, and also to superintend the pumping arrangements, were too perfect to be overcome, and out, forth into the grasp of their friends, were brought the entombed.
The excitement at the top of the shaft was nothing equal to that below. The grave giving up its dead, the solitary shrouded form rising from its trance, was nothing compared with that procession of five, borne one after another, carefully tended by doctors and assistants to the bottom of the shaft.
Instruments used in mining
The Coal Mines Regulation Act states that ' a barometer and thermometer shall be placed above ground in a conspicious position near the entrance to the mine' and it is well that we should understand the advantages gained by having these instruments within easy access to miners and mine officials.
The barometer is used in mining because it registers the pressure of air, and , by showing variations in the pressure at the surface foretells to a certain extent the volume and pressure of the air circulating through the mine. This assists the engineer in preparing for increased issues of gas from the strata, and troubles such as falls of roof and sides. We know that the volume of air varies inversely as the pressure, therefore the causes influencing a rise or fall in the barometer also influence the volume of air circulating in the mine.
As the gases in the coal and the cavities along the roadways of mines are kept there by the pressure of the air circulating through the mine, it will be easily seen that when the pressure is diminished the gases will have a greater tendency to pass off into the air current and make it explosive. Knowledge of this fact has caused barometrical variations to be carefully watched so that warnings may be sent to mining districts of any sudden changes which may be expected.
In one year the Government issued 32 warnings, and 19 of these were justified by subsequent events. Twelve of the warnings were followed in 3 days by explosions in mines causing 139 deaths; two were followed on the 5th day by explsoions causing 43 deaths; 23 lives were lost on the 6th day; this shows a total of 205 lives lost in 6 days whilst 5 were lost on the day of issue.
The mercury in a barometer is 22,000 times heavier than fire-damp , the latter is thus much more susceptible to changes in the atmosphere than mercury. owing to this fact disturbances will have frequently occurred in a coal mine before a barometer at the surface has shown any change. If it were possible to construct a barometer more sensitive to atmospheric changes, yet equally convenient for handling, then the advantages of its use would be much appreciated by mine officials.
The height of mountains and the depth of shafts can be conveniently measured using a barometer.
The thermometer is used to tell a mine's heat or temperature. By ascertaining the temperature of the air in the upcast and comparing it with that in the downcast, we can gauge the work done by a furnace in ventilating the mine.
By the use of the thermometer we are also able to tell the difference in the temperature of the intake and return air currents, as well as the extent of any gob fires which may exist. As the temperature of the air plays an important part in ventilation, the value and use of this instrument in mines is self evident.
This is an air speed measurer used to measure the velocity at which air travels through a mine. As the first general rule of the Coal Mines regulation Act refeers to monthly measurement of the quantity of air passing through a mine it can be seen what this instrument's use is.
Used to measure the ventilating pressure in mines.
How the coal is raised
For many years coal was brought from the working places in the mine to the surface in baskets, carried on the backs of women and boys, who climbed the ladders placed in the shafts.
At modern collieries where as much as 2000 tons of mineral are raised in 10 hours from a depth of 2000 feet, it is necessary that large and strong winding engines should be erected. They may be vertical or horizontal, condensing or non condensing, but they are almost invariably placed in pairs to avoid unnecessary trouble, and are direct acting, that is, the piston is coupled direct through the connecting rod to the crank keyed to the shaft on which the winding drum is placed. They may be driven by steam , oil, water, compressed air, or electricity, and are of enormous strength, reaching occasionally as much as 3000 horse power. The Coal Mines Act makes it necessary that they should be provided with adequate brakes, indicators showing the position of the cage in the shaft, and that the engineman should be above 22 years of age.
The headgear constitutes a very important part of the fittings of a shaft. It consists essentially of a pulley frame constructed either of wood, wrought iron, or steel, carrying a pulley, or more frequently two pulleys, over which the rope suspended in the shaft is passed, and led thence to the winding engine. These pulleys are provided with a round or flat groove according to the form of rope used, and are made of a large diameter in order to avoid giving a sharp bend to the rope. Sometimes the pulley frame reaches a height of 90 feet.
Are made of cast or wrought iron, and vary from 10 feet to 20 feet in diameter.
The pit rope constitutes the means through which the force developed by the engine is transmitted to the load, as such it is an object of great importance. It has to be flexible and strong, with the least weight possible. hemp was used until a few years ago, later aloe fibre was adopted, but now the best steel is universally used. The rope may be round or flat.
The winding rope is connected to the cage chains by means of what is known as the rope capping. There are several kinds, one method involves the sue of 2 semi circular hollow pieces of wrought iron which form a hollow cone of the same internal dimensions as the conical mass of the rope end which has been prepared.
It was the custom for many years to tip the coal as it arrived at the shaft into vessels of various forms, in which it was raised to bank. These vessels were allowed to swing loose in the shaft, so that it was impossible to wind at high speed, and if the vessels struck the shaft sides both it and the rope were destroyed. Eventually a system of cages moving between guides was adopted. The cages are generally of iron construction, made to contain one or several tubs which are in this way raised through the shafts with their contents. They are made to run between guides so that they may be raised with great velocity--from 15 to 50 feet per second.
The 'bridle' chains connecting the cage to the rope are usually 6 in number, being place one at each corner, and one at the centre of each longest side. These chains should be made of the very best quality iron and taken off every 3 or 4 months to be examined and annealed.
Keeps or Keps
When the cage has been raised to the mouth of the shaft, some means are needed for supporting it in that position. These means usually consist of a system of levers called, from their use, 'keeps' which are raised by the cage as it ascends, and which, by being weighted or otherwise, drop back into position as soon as the cage passes. The cage rest supon these 'keeps' while the loaded tubs are being run off and empty ones run on.
The Coal Mines Regulation Act makes it compulsory that guides should be adopted in all shafts over 50 yards in depth. Sometimes they consists of two vertical stips of wood, or guide rails, attached to the lining of the shaft. At other times steel ropes are suspended from the headgear and weighted at the bottom of the shafts, and thus used as guides. Steel rails rigidly fixed to the sides of the shaft are frequently used as guides in deep shafts.
The rope, after passing over the pulley at the top of the pit head framing, is led to the widing drum in the engine house upon which its is coiled. The drum may be spiral, cylindrical or conical in shape but must be strongly built. It often reaches a weight of 80 tons. It is made of wood or steel. Its diameter is determined by the nature of the rope and depth of the shaft but it reaches in some cases over 30 feet.
To prevent accidents in case of over winding safety 'hooks' or 'catches' are used. These are so made and placed that when over winding occurs, instead of the cage with its load veing drawn over the pulleys, they come into action at a prepared spot in the headgear, and hold the cage firmly in position at the same time permitting the rope to pass off to the engine house.
British Coal Fields
This section is largely not extracted but for these snippets below;
Annual production of coal in Great Britain
- South Wales ---29 1/2 million tons
- North Wales---3 m tons
- Monmouthshire---9 1/2 m tons
- Scotland---c 33 m tons
- Great Northern---45 m tons
- Cumberland---2 m tons
- Midland coalfield---52 m tons
- Lancashire---23 1/2 m tons
- Staffs, Worcs, Wars, Shrops, Glos, Dean, Bristol--- 19 1/2 m tons
- Somerset---1 m tons
- Ireland--- one tenth m tons
Before the coal is loaded into the railway trucks for conveyance to the port, it is carefully weighed and screened. In the screening process the small is carefully separated from the round and large. Many inventions have been introduced for mechanically classifying the coal according to the needs of the manufacturer. At some of the modern collieries plant for thus dividing the coal into 5 separate classes is used. Where the small coal is intended for coke making it is carefully washed in troughs, when all dross is removed.
Patent fuel is made from carefully washed small coal and a cementing material with which it is mixed.
In 1800 the shipment of coal from this country abroad was 225,000 tons; in 1850 it was 3,351,000 tons; in 1900 it was 58,405,000 tons
Coal Mining - a Reader [Last Updated : 23 Oct 2002 - Gareth Hicks]