Tech Talk - is coal that dirty?

So when was the last time, reading an article about the coal industry, that you saw a photograph of the land after the mine has closed, and the site reclaimed? Or, in talking about an oil or gas rig, how many times do you see the relatively small footprint at the site, once the rigs have left, and the site is reclaimed so that all that is left is the production tree?

The fossil industry tends to be vilified at regular intervals with very few voices raised to murmur slight protest as to the picture painted of its evils. The Economist had an article this week which said, in part:

And coal would indeed be a boon, were it not for one small problem: it is devastatingly dirty. Mining, transport, storage and burning are fraught with mess, as well as danger. Deep mines put workers in intolerably filthy and dangerous conditions. But opencast mining, now the source of much of the world’s coal, rips away topsoil and gobbles water. Transporting coal brings a host of environmental problems.

Note that there is no comment about putting the topsoil back in place after the mine has passed, or re-establishing the land fertility. Laws passed in the 1970’s have ensured that the land reclamation is to a much higher standard than previously, and reclaimed land in Ohio, for example, is now harvested for hay and used for pasture. And it was possible to get 43 acres of recreational land filled with lakes full of fish etc for some $107,000 only a couple of years ago.

Figure 1. Reclaimed mine land that was for sale in Illinois (MidWest Energy News).

Now it is true that working underground will get you dirty – in the same way as it will if you are working in the tunnels of a subway system, or on a farm, not to mention repairing sewers – but unless it is the color of the dirt that leads to the discrimination – working in a job that can get you dirty has not, in the past, led to the disapprobation that one sees in papers such as the Economist these days.

The concept of working underground by itself cannot, surely be something of concern. There are all sorts of buildings that have been built underground – either in regions where the site was first an active mine which then converted into offices, warehouses and storage facilities, or where the plan, from the beginning was to mine the space for a specific purpose (whether a subway line, an underground school or public baths or other useful place). For example, consider Springfield Underground which I first visited over four decades ago, and which can run up to 100 ft below the surface, although there are entries where trains and trucks can have access.

At 2.4 million square feet, Springfield Underground continues to grow; we have ample space available for your unique application. While we can accommodate all sorts of businesses, Springfield Underground is home to warehousing, laboratories, food storage, records storage and data centers. Our location is convenient to railways and highways – which makes us ideal for distribution centers and manufacturers.

Figure 2. Cutaway showing the location of available space at Springfield Underground (Springfield Underground)

By utilizing the space between pillars (shown in white against the blue available space) and building temporary walls work spaces of thousands of square feet are located underground where they are safe from tornadoes, which are a hazard for the state, at a constant temperature and in relative quiet and security.

Similarly there are facilities under downtown Kansas City and in a number of other locations around the country.

“Intolerably filthy and dangerous” – well that dates the information that the writer is basing this on. Of course there are the images and stories of the past:

Figure 3. The Penitent by Hildebrand

When I was young I lay on my side and worked with a pick and shovel in low coal, not that much different from the conditions shown in Anthony Burton’s “The Miners.”

Figure 4. Mining in Low Coal at Condering Colliery. (The Miners)

But that was over 50 years ago, when Britain still desperately needed the coal to fuel its restoration and modernization, and where there was also a provision to keep mines open to help with employment.

Now those narrow seams are largely not economic to mine (though there are ways) and modern coal mines use large mechanized methods to remove the coal, often remotely from the work force. But the image remains.

Increasingly mines are much safer, there is a fair amount of white stone dust on the walls so that, as well as being better lit, it is also just a brighter place to be.

Figure 5. A modern longwall production face (Maple Creek via West Virginia University )

While, in the unregulated mines of the past there were death rates of up to 1,500 or more in the United States (at one time explosions underground could kill all the miners underground at the time of the explosion, and this could add up to more than 200) there were 19 miners killed in 2012. And while one death is too many there are sadly other industries that have a worse record.

According to Forbes, the ten most dangerous jobs in 2012 were:
1. Logging workers

2. Fishers and related fishing workers

3. Aircraft pilot and flight engineers

4. Roofers

5. Structural iron and steel workers

6. Refuse and recyclable material collectors

7. Electrical power-line installers and repairers

 8. Drivers/sales workers and truck drivers

9. Farmers, ranchers, and other agricultural managers

10. Construction laborers

Mining didn’t even make the list, nor of the more extended list of the 15 most dangerous jobs, as listed by AOL.

Sadly the industry has been stereotyped with an antiquated, and largely out of date set of images. (Though admittedly in parts of Asia particularly the low cost of labor and the need for both jobs and fuel can still lead to the odd dismal picture, yet even there, as regulations set in the picture is improving by the year).

One has to look no further than to the photographs of power stations that use coal to see the evidence of this bias. The only visible vapors that leave a modern plant are the steam clouds and yet in paper after paper the photographer has maneuvered so that, with the sun behind the steam, it looks grey or black.

These distortions are having less and less impact, as the real long-term need for coal is clearly evident, but it just makes the debates less honest. Unfortunately the image of underground workers are too often associated with the Trolls and Orcs of Tolkien's Middle Earth in contrast to the desired world where we see the contrast to the idyllic but unrealistic dream of us all living in the Shire in bucolic joy for ever.

Pre-mechanized longwall mining

In the last post on this subject, I wrote about how miners were able to remove almost all the coal from a section, either by leaving small remnant pillars or building packs to hold the roof in place, while that coal was removed. By retreating the face back towards the shafts the overlying roof rock was then allowed to collapse into the void left by the coal removal. However, as this process began to evolve the miners noticed a couple of significant things that helped in the understanding of how the roof was responding, and helped to make longwall a safer and more effective method of mining. The first was that at the roof broke behind them, so the rocks would bulk up (they gain about 60% volume as they break and pile). Within a distance of about 2 seam heights, as the roof was converging, without underlying support, it would then meet the broken pile of rock, and thus get some support from this. As a result any support that the miner installed would not need to carry the full weight of the overlying roof to the surface, but only that of a few feet, which needed much less strength.

Thus by about 1870, and possibly in the Lancashire coalfield in the UK, they had modified the process further, and were only supporting the roof around the actual mining operation. How could they get away with this?

There was one other fact that helped make it possible. In some of the earliest tech talks I mentioned that the weight of the overlying ground can be simplified to being around 144 lb./sq ft for every foot of depth – based on the simplifying assumption that a cubic foot of rock weighs 144 lb. Thus converting this to a pressure in lbs/sq inch. (of which there 144 sq ins to a sq ft) this means simplistically that for every foot of depth one goes into the ground, the pressure increases by 1 psi.

Now when you make a hole in the ground, that load, or equivalent rock pressure, has to move somewhere. And it moves just a little so that the weight of the ground over the hole is carried by the rock on either side. However, what happens if this additional load is too high for the rock and it fails?


Well if the rock were just a thin column it would collapse, but if it were thicker, then the weight would just move further into the coal. Now if we came along and moved the coal that had failed, then the hole would just continue to get bigger. But if we leave the coal in place, then the broken coal acts to confine the coal further into the solid. And this confinement gets higher, as the failing pressure continues to move into the wall. And what happens is that this confinement builds up the strength of the coal, so that at some distance into the wall (or face) the coal strength reaches a point that it can carry the weight of the ground above the working area.(For a simple analogy think of a deck of cards, which individually cannot bear weight, but when held together by a rubber band, or a carton, can support quite a bit of weight). (And for those who prefer a more scientific description – the lateral confinement moves the failure from two-dimensions into three, with the minimum principal stress building as one moves into the solid material, and raising the overall failure stress behind it).

This works not only for the coal in pillars, or ahead of the working face of the longwall, but also for the rock that has fallen into the waste and is confined by the rock around each piece allows it to regain some strength, and so collectively the broken rock behind the working face (called the goaf or waste) will continue to compress as the full load comes on it, but will carry the weight of the ground from about twice the seam height, all the way to the surface, and with the other end of the "bridge" as it were resting on the confined coal ahead of the working face.(While the width of this bridge varies with depth, coal and rock strength etc, for an initial estimate you can imagine it as being around 500 ft).

Simplified side view of the coal as the miners removed the coal along the face, moving to the left. They put up wooden supports (three wooden props and a top bar) and let the roof behind the working face that these protected, collapse.

Thus the miner, working at the face, needed only to support only the rock that is up about twice the seam height he was working (in those days women did not do the actual mining). And this could be done with relatively small tree limbs, called props. However, because the rock could break into pieces, the prop support would be distributed, by having a plank, or half split timber, as a bar on top of the prop. Putting one prop at each end thus gave a sort of "goal post" support. Thus, along the face, there would be, at about 4-5 ft intervals, these prop supports holding the roof up.(The coal is made slightly blue in the pictures to give a better contrast - sorry!)

View looking down on the working area from the top of the fallen rock pile. I have erased a small section of the coal to show the position of the cutter bar of the coal-cutter as it is either dragged, or self propels itself along a cable stretched down the working face.

In the initial working of the longwall panel, the coal was undercut by a team of holers, who each cut a slot at the bottom of the seam, to a depth of about 3-ft, and collectively undercut the face over the course of a shift. As the faces grew longer there was a search for a machine that would make that undercut without the intensive manpower. One such tried to mechanize the simple swinging action of the pick.

Early coal cutting machine used at Garth Colliery in Wales in 1863. (National Museum Wales )

The development of the machine, the coal-cutter, dates from around 1876 when a compressed air machine was developed by Francis Lechner, in which picks mounted on a chain, did the cutting of the coal. (The more modern versions of this look like a chain saw on its side). It took a number of years for the machine to evolve into something that was widely accepted, and by that time the company had been taken over by Joseph Jeffrey (a banker) and became Jeffrey Manufacturing Company. (By the time my dad worked for them they had become British Jeffrey Diamond, and they later became part of the Dresser Group). They had spread to Europe by 1905.

And electrically driven machines were developed, which have not changed that much in the intervening years.

Early Coal Cutter (Iron Miners )

With these machines pulled along the face, undercutting the coal, to give a cut depth that was more typically 7-ft deep, the next step was to break down the overlying coal. Sprags (small wooden wedges) were slipped into the slot at intervals, as the cutter passed up the face – usually run by three men. At the same time holes were being drilled along the face, about 6 ft apart, with a stick of dynamite placed in each one.

After the face had been undercut the coal was blasted down between shifts (7.5 hours) then the collier shift would come in and each man would have about 10 yards of face to load the coal from, and to re-support. To get the coal from the face, a rubber conveyor belt was run along the back end of the supports that were in place before the blast, and the coal would normally not break that far from the face. As the miner shoveled he would also put in a new set of timbers, overlapping the old, and supporting the new working area. Typically this would take another seven hours, with an ideal seam height being about 4.5 ft. Above that the coal volume to move was much greater, and below that it got a bit awkward. For example, below 2 ft thick you lie on your back, with a prop under your shoulder and shovel over your head - how would I know? Yes, there was a reason to go to college).

View of the face, after the coal has been loaded out. The rubber coal conveyor between the last two rows of props must now be broken into strips, and moved forward a row, ready for the next cycle. Then the back props and bars are removed. (Saving the front two props and chopping out the back one).

In the third shift, the men would come in and break down and move over the conveyor belt, and then remove the last row of wooden supports, bringing the roof down, beyond the new line of supports.(Smart folk would use a come-along and a chain to pull down the props, young idiots (guess who) would go in with an axe to chop them first). For this was the state of the industry when I went to work in it in 1961. There have been many changes since.

Manually mining coal underground

Since last I wrote I have travelled to London and then up North into southern Scotland (I write this looking down at the station in Dumfries, having passed the one-time house of Scotland’s Bard). Today I would like to continue writing on some of the historic methods of mining coal, in part because, in certain parts of the world, this is still the way it is done.

Last time I had talked a little about how mining started where the coal seam came to the surface, or outcropped, and that miners worked their way into the hillside digging the coal out creating both a passage deeper into the seam, and also leaving some pillars, as they widened out the passage way to mine more of the coal. Other times, as the coal became deeper, instead of working from the outcrop, they would sink a small shaft, and mine coal out from around its walls. Because the mines thus had the narrow shaft and then widened in the coal seam they became known as bell pits. They were used in parts of Northumberland as late as World War 1. The miner would break out the coal with a pick, and hand load it into baskets, or corves, that would then, initially be carried up the ladder by children or women. However as the mine got deeper the ladder haulage would be replaced by a hand-turned winch, or later and for deeper mines, a horse gin or other winching system using an animal.

Picture of bell pit

Picture of horse gin
A two-horse gin is reported to have been able to raise some 2.5 tons of coal an hour.

As demand grew, so the underground mining pattern would grow with it. This may was from the Kehley’s Run Mine in Shenandoah, PA. The plan shows how, from the original drift into the side of the hill, the mine spread out along and behind the outcrop, leaving as small a pillar as possible to hold the roof up.

Partial plan of Kehley’s Run Colliery at the time of an underground fire in 1880. The red areas show roof falls. The cracked black are broken pillars, while solid black are pillars with some strength and integrity. (I have cleaned the image a little with Photoshop)

You can see in the illustration how the mine (the current entry is at M, the earlier entry having been closed by the roof collapse shown) mined as much coal as possible to leave the least amount of coal, and that this could cause roof falls. I mentioned one of the fires at the mine, but this mine also raised attention from one of the many riots that erupted between miners, mine owners and their security guards.

Some of these stories have been dramatized in movies such as the “Mollie Maguires”, but it was a grim and vicious set of confrontations based on grim working conditions. In one seven year period some 566 miners were killed and 1,665 were injured in Schuylkill County, PA alone.

Confrontation at the Kayley's Run colliery 1888 (after Popalis )

You might be able to get some sense of the grim conditions from the mine plan. Conditions had been worse in Europe. There are a number of nasty things that can happen in coal mines. As we recently saw and heard, one of them relates to the gas that is given off during mining. Like natural gas from other sources, in ranges from 5 – 15% this methane can be explosive and thus the levels of gas must be kept below this level (hopefully below 1%) if the miner is to be safe.

The other gas that had to be watched for was carbon dioxide, which in contrast with methane, which being lighter than air collects in the roof, is heavier and thus pools on the floor. So that if you were getting down to cut the starting slot in the bottom of the coal seam, you might just drop into a pool. It was called choke damp – though that was also the name given to carbon monoxide, which could also seep out of the coal. All these gases are colorless and odorless so that without some form of detection (the canary for example, or using a candle as a test) they can lurk to catch the unsuspecting. With the invention of the safety lamp (where the heat of the flame is removed by a surrounding mesh of copper wire) it became possible to use the lamp itself as a testing tool. One of my first mining tests was to make sure that I could tell, by the height and shape of the small blue flame of the methane burning over the lowered flame in the lamp, what the gas concentration was. (Each lamp was in a separate hood, and I remember that they had two at the same concentration in the set of around half-a-dozen I had to evaluate).

Methane caps on a safety lamp flame (Colliery Deputy’s Handbook)

When the miner saw the flame cone, he would first wave a shirt or towel to stir the methane into the air, hoping that the concentration would fall below 1%, but if the level built up, he might have to leave, or call for more drastic measures to get rid of it. Back in Medieval times there was an individual called The Penitent, who would wrap himself in wet rags and crawl into the mine with a candle on a long stick. Raising the candle to the roof, he would ignite the layers of methane that would gather there, before the rest of the miners came back into the working. Methane, being lighter than air would gather in the roof, when the air currents were not strong enough to mix it into the air and remove it.

The Penitent – an etching by Hildebrand

But, as they mined coal from further away from the shaft, the air would not easily move around the workings, and since the coal would give off other gasses, as well as methane, there needed to be some way of circulating the air. And so the miners began to run sets of tunnels out into the coal that ran parallel to one another, but with cross tunnels (cross-cuts) between them so that they could circulate air around and up to the working area.

For many years, starting in around 1810 the motive power for the air was created by having a fire in the bottom of the shaft, in a special furnace room. Usually these were underground, although there was the occasional one at the surface. Unfortunately if the fire ignited the surrounding timber that was being used for support, then a major fire could result, killing everyone underground. This was the case with the Avondale mine disaster in 1869, at the time the worst industrial accident in American history, 110 people died.

At first there was only one shaft or tunnel leading in and out of the workings, but a major accident occurred at New Hartley in Northumberland, UK in 1862 where the main beam for the dewatering pump fell into the shaft, blocking it. The 199 men and boys in the mine, virtually the entire working male population of the village, were all killed, It was a result of those deaths that legislation was passed that required that there be two separate ways to get out of a mine. Where the mine is deep underground this means that there are generally two shafts, or more from the workings to the surface. (My Dad was manager at the resurrected mine, and the village school was the first primary school that I went to).

Initially men broke the coal from the solid with picks. To mine more efficiently they would first swing the pick along the bottom edge of the coal, and cut a slot that would be perhaps a couple of feet deep. Then they would drive the pick into the cracks in the main seam section and break the coal to the edge that they had created. When they worked this efficiently, a man can be very effective in breaking out the coal (about 4 joules/cc specific energy, for those that are interested, The machines mine at around 1,000 joules/cc of coal removed).

As the working face grew away from the shaft, it became too slow to rely on women and children to carry the baskets, on their backs, to the shaft and up out of the mine. ( A woman was reported to be able to carry about 56 lb of coal at a time. So first rails were used to slide the baskets along. Then wheels were added, first to flats, and then to small tubs. At first these were of wood, but then were changed to metal.

Although there are still parts of the world where this type of primitive mining still occurs, and where women and children are used to help get the coal out, in most countries they have been banned from underground work. (This was the Act of 1842 in the United Kingdom) . Taking the coal from the miner or hewer to the shaft was known as putting or hurrying. (I learned it as putting).

Six year old girl:
"I have been down six weeks and make 10 to 14 rakes a day; I carry a full 56 lbs. of coal in a wooden bucket. I work with sister Jesse and mother. It is dark the time we go."

Jane Peacock Watson.
"I have wrought in the bowels of the earth 33 years. I have been married 23 years and had nine children, six are alive and three died of typhus a few years since. Have had two dead born. Horse-work ruins the women; it crushes their haunches, bends their ankles and makes them old women at 40. "

Maria Gooder
"I hurry for a man with my sister Anne who is going 18. He is good to us. I don't like being in the pit. I am tired and afraid. I go at 4:30 after having porridge for breakfast. I start hurrying at 5. We have dinner at noon. We have dry bread and nothing else. There is water in the pit but we don't sup it. "

With time horses (or pit ponies as they were called) were taken underground and used to haul the tubs. Ponies were used for haulage well into my working career, and leading one was the first underground job that I had, when I worked in the mines before going to college. They served two purposes, being used firstly to haul the coal from the face, but also to haul wood back to the working area, where the miner would cut the wooden props to length and then wedge them against the roof to hold it up while he worked under it.

Because of low cost, the tubs had very crude axles, and so, to go around a turn, one had first to stop the pony, then switch the points on the rail, then start the pony round the turn, then run back to the back end of the tub, and manually twist the tub so that the axles turned to align with the turn. Fail to do any one of those and the tub came off the rails, meaning you had to unload it, put it back on the rails, and then reload it – all the while with the pony standing there enjoying the break.

Because a man with a pick is, though efficient, quite slow, machines were developed where a large number of picks were set into a chain, rather like a large chain saw, and this was used to undercut the coal seam about a hundred years ago. Then holes were drilled into the coal above the slot, filled with a stick of dynamite, and the blast would break the coal into pieces, that the miner could load into tubs. Typically he might load some 20 tubs in a shift, and these were hauled out of the working area by one of the lads, who would then attach those from several of the faces, and pull the resulting train to the shaft using a pony.

He would put his “token” in the tub before he would fill it, and so, when the tub was emptied at the surface, he would be given credit for that coal, providing it did not have much stone in the pile.

Early mining and transportation of coal

On the 18th April, Ugo Bardi posted a piece on The Oil Drum discussing some of the dark sides of coal mining. In particular he started with one of his favorite paintings “The Riverbank’ by Telemaco Signorini. He ties this picture of men towing a coal barge into a memory of his earlier life. And so, from the other end of that supply chain, that brought coal to Florence, today I am going to talk about the early history of coal, but from the region around Newcastle, and further north up by Alnwick, which is where my coal-mining ancestors came from.

When I saw Ugo’s painting I was immediately reminded of the movie “1612” which has, in a more modern recreation, more than five men hauling a boat.

Towing a boat – from the movie “1612” directed by Vladimir Khotinenko

The commentary that comes with the DVD makes some point of the difficulty in hauling the boat, even though it was relatively small and there are more than twice as many men as Ugo portrayed. It was also unladen.

Though the crew look strong, they are after all actors, and are attached to the boat by a harness of ropes that it likely take more time for them to learn to properly operate than they had for that shoot. (As one of the comments on Ugo’s post noted, this scene could have been taken to reproduce the Russian painter Ilya Repin’s painting “Burlaki” which it emulates).

Ugo also deals more with the political constraints in the coal trade after 1860. Since I am more concerned with discussing reserves and methods of mining and the more technical considerations, I am going to start a little earlier in the use of coal, when it was mined in the UK, and some of the early practices.

When coal was first used, the legends have it that it was collected along the sea coast near Tynemouth in the North-East of England, and taken to the local priory and the rights to the coal were given to the monks. (The scene is illustrated in the movie “Nine Centuries of Coal.” (Which if I understand the BFI rules you can download if you are at a British University or school).

Coal was used to provide the fire for the local lighthouse at Tynemouth until about 150 years ago. The monks did well by their ownership of the coal rights, by 1281 they were shipping the coal down to London where it brought nineteen shillings a chauldron. (There were 20 shillings to a pound, which is currently worth $1.44, though the value has historically been higher). A chauldron was a wagon that would hold around 80,000 cubic inches of coal or just over 45 cu. Ft. of coal, or about 1.7 tons of coal, when it was mined. when it got down to London the measure changed so that while whle, by one definition a chauldron was 36 bushels, but

8 chaldrons at Newcastle, makes at London about 15 chaldron.

The unit was abolished in 1963.

1870 Chauldrons at the Beamish Mining Museum (Terry Pinnegar )

So we know that coal was heading down to London, where King Edward (because the fumes apparently sickened his mother) banned it, with the threat of torture and death to those that used it. (This is the king that had Wllliam Wallace, as played by Mel Gibson in Braveheart, chopped into bits, while alive, so he generally wasn't someone you wanted to mess with). But is was sufficiently cheaper than the wood alternative that the ban had little effect, and coal has been a major fuel in the United Kingdom ever since.

The king, incidentally, was compensated in other ways, since a royal duty was imposed on the mining and shipping of coal, that brought in a large income over the years. In 1818 the mines were estimated to produce 15 million tons a year, for domestic use, with additional amounts used by industry. The duty was 9 shillings and four pence to London, and 6 shillings to other ports in the UK. And this brought in a revenue of 570,066 pounds in 1816. Some 2.25 million chauldrons of coal were shipped, roughly half of which originated in Newcastle. The coal was generally taken by rail, though hauled by horse until the invention of the locomotive (by a local miner), down to the river where equipment known as “drops” were used to swing the chauldron down to the collier for unloading.

The staithes at Wallsend by Hair (1844)

The staithes includes the short pier and feeds to the drop.

At its extremity is fixed the drop, consisting of a square frame hung upon pulleys, and counterbalanced by back weights. The loaded wagon, together with the square frame, descends by its own gravity to the hatchway of the vessel, delivers its coals, and, in turn the empty wagon is returned by means of the balance weights, the motion heing in both cases regulated by a brake wheel. A man is lowered down with the wagon , whose business is to unhasp its moveable bottom, and thereby let the coals drop into the hold of the vessel.

The drop was patented in 1800 by Wm Chapman. A tapered spout led the coal into the hold of smaller keels (the boats used to carry the coal out to larger ships). The main coal mined came from the Bensham and I 1836 93 ships carried some 15,519 tons of this coal through the staithe at Wallsend to London, where it sold for 7s 9d a ton, while one ship carried 318 tons from the Bensham Wallsend, and it sold for 8s 6d a ton. (Personal note – I have worked in the Bensham seam, albeit some 125 years later).

Mining had progressed by that time from the initial collection of loose coal washed up on the beach (sea coal) to mining it where it outcropped, and then mining back into the seam outcrop from the surface, and this often meant that the tunnel that was mined sloped down into the ground. The dirt that was mined out was dumped at the entrance to the tunnel, and often created a small narrow feature on the ground, a tip, some of which can still be seen today. Our family, for example, used to be coal miners at Eglingham. This is a small village found in the North East of England, not that far from the Scottish border.

Aerial view of North of England (Google Earth)

I have marked an overview of the village with a couple of arrows to show where the two tips were that I have walked around (and where my ancestors no doubt worked) on an overall view of the village (using Google Earth) which is at the bottom of the picture. Given the fact that I am going to show you that it was a mining site, it was wryly amusing to see signs in the local parish hall asking for action to protest the location of wind turbines on this "pristine English countryside."

Eglingham (Google Earth)

Right in the center of the picture however, if one zooms in until GE tilts a bit, you can see a third tip quite clearly.

Pit tip at Eglingham (Google Earth)
My aunt (the Teacher) had done some research on where we lived, and this was not down in the current village but up where the top left arrow points, and where all that is left of the houses are circles where the gorse grows, but where rabbit warrens have brought up small pieces of china, and other remnants of the time that folk lived there, only a couple of hundred years ago.

Ruins at Tarry, near Eglingham (55deg 28”55.84” 1deg 49”43.76W)

In those days it was pre-mechanization, and the miners used only a pick and a shovel to break the coal from the solid. It was then put into woven baskets called corves, that were dragged to the surface on a wooden board, either by younger boys, or by women. The board would slide up the tip, and could be dumped before being dragged back underground. The tunnels were driven to the height of the coal, which in the area may have been somewhere around 4 ft 10 inches (with an interbedded layer of stone that ranged from 3 inches to 2 ft thick) or 5 ft 8 inches, (with 3 ft of interbedded stone) not the richest of workings. It was only after some years, and larger mine developments that the baskets went from being carried on folks backs, or on these boards, to being put on flat cars and moved by rail.

Bottom of the shaft, Walbottle Colliery Hair (1844)

Stephenson, who invented the Rocket, the first locomotive as a way of hauling mine chauldrons down to the staithes, began his working career by weaving canes into these corves in a pit yard.

In these small operations, with all the excavation from the initial tunnel into the side of the hill, the coal was mined by individual workers, or families. The miner would work with a candle as a light, and that would be mounted to a wooden post that he would use to hold the roof up.

Undercutting the coal

Laying on his side, he would then take his pick and cut out a slot at the bottom of the coal. This undercut, perhaps 3 ft deep, would be cut along the total face of the coal, before the miner would start to work up. Depending on the size of the tunnel he may also make a vertical cut to create a second free face. (You can see some of these markings in the walls of old stone quarries, and in the mines under Bath in the UK, and the salt mine at Wieliczka in Poland). He would then break out the coal in individual lumps that were several inches in size. (4-6 would be ideal). If he used the joints (called cleat) and the bedding planes of the coal, then this was not too difficult to do, and so he could mine out several chauldron’s worth of coal in a shift. In the measurement of the work he did using a modern measure it would take as little as 4 joules/cc of energy to break out that coal.

Wall at Wielicza, showing the pick patterns used to cut the initial slot to which the rest of the rock would then be broken.

A typical shift would be around 8 hours, but it shrank, so that when I went into the mines it lasted only 7.25 hours. As well as mining the coal, the miner had to hold up the roof, and, if there was a roof fall repair it. But of all his concerns the most prevalent was that of gas. Remember both that he had to breathe, and that coal emits methane, or natural gas, from most seams. The methane will burn, or in the right concentrations in the mine can explode. And when that happens it consumes all the oxygen, so that even if the miners aren’t in an area where the explosion happened then they may still die as the de-oxgenated air circulates underground.

Initially the miners would work only a short distance into the outcrop and though the mining site here was worked at least from the early 1700’s, in the south of England miners had already learned to sink shafts and to mine out from them – but I will get to that next time.