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Chronology of the development of
TWO CENTURIES OF REVOLUTIONARY CHANGE
The Industrial Revolution
The Search for New Power Sources
Development of Coal Mining
It was realised that if an independent power source could be found it would be possible not only to power the mill factories with it, but also to locate the factories near good road networks and population centers. In other words, the place where a mill was built would become independent of any natural power source.
At this time there was an increasing need for fuel for heating and other purposes. Traditionally, wood had been the universal fuel, but, by the 18th century, the forests had become severely depleted and supplies of wood were becoming scarce and more expensive. Coal was therefore becoming more important as a fuel, but as its production increased, so did the difficulty of extracting it from the ground.
At first, most of the coal was extracted from adit mines (horizontal tunnels running into the sides of hills). As these became worked out it became necessary to dig downwards towards the coal seams.
First a vertical well shaft was dug to find the seam. Then the sides of the shaft were dug out in a circle. This formed a bell-shaped hollow in the ground. It was a very dangerous practice because no method of shoring up the overhanging rock was used. Consequently, it was often the case that the mine collapsed onto the miners. (It is not surprising that this type of construction was called a suicide pit!)
This type of mining was slowly replaced with deep mines in which the vertical shaft was connected to the horizontal shafts. These were shored up with timbers as the mine was dug out. The deep miners were faced with many problems.
Two of these were stopping the mines from flooding and providing the miners with fresh air. Previously, these problems had been solved by using power supplied by mill wheels which both drained the mines and ventilated them. However, this could only work if the mine was close to a sufficiently powerful water supply.
All about Coal
By the end of the 17th century, wood was becoming less available. England and Ireland had once been covered by deciduous forests. For centuries these natural forests had been destroyed to provide the population with fuel. Now Ireland's supply was exhausted and England's forests were greatly diminished. There had been unsuccessful attempts to ship in timber from New England. In order to supply the demand, wood was now imported from Sweden and Russia. Wood had become an expensive commodity.
The other natural source of energy available in England was coal. In fact, as shown on the table below, coal has a higher carbon content than wood. This means that it is a more efficient fuel. When wood or coal are heated to about 1200°C in the absence of air (oxygen), they provide charcoal and coke respectively. Both charcoal and coke have higher carbon contents than wood or coal which means that they make even more efficient fuels.
Coal had been shipped from Newcastle to London during the Middle Ages. Now other coal seams were exploited. Whereas wood had once been readily available in all parts of the country, coal was confined to certain regions, notably South Wales, the Midlands and the North. Since South Wales and the Midlands were also the sites of iron ore deposits, and there was no efficient system to transport raw materials into other areas, by 1750 these two regions became popular industrial sites. It was only in the 1790's, when the canal system made transporting raw materials to other areas a viable option, that industry really developed in other parts of the country.
Coal mines were dangerous places in the 18th century. In order to ventilate the underground tunnels, a fire was lit at the bottom of one of the access shafts. This created hot air which drifted upwards and drew fresh air into the tunnels. Unfortunately, carbon monoxide and other explosive gases were common in coal mines. There were frequent explosions and fires.
The table below shows the increase in coal production during the 18th century. Coal output was able to increase so rapidly because steam pumps were developed which enabled deeper seams to be exploited.
Some of this coal was converted into coke. To make coke, coal has to be heated at a temperature of 12000°C in the absence of oxygen. This is called the destructive distillation of coal. The process also produces a colourless, explosive gas which is a mixture of hydrogen and methane. In 1792, William Murdock devised methods for purifying and storing this gas. He put the gas into a gasometer and, by 1794, he was using gas to illuminate his house and office. Eventually, coal gas was used commercially as a fuel in towns. For this reason coal gas is also known as town gas.
Coal played an extremely important role in the industrial revolution. It provided the high temperatures needed to extract metals from their ores (metallurgy) and to produce the steam needed to drive the industrial steam engines.
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