IELTS Academic Reading Practice Test 9: Passage 1

Few objects are as ordinary as the pencil, yet the familiar wooden stick with its dark core is the result of several centuries of discovery and experiment. Its story begins in Borrowdale, a valley in the Lake District of north-west England. According to a popular account, local people there came across a deposit of a black, shiny substance in the middle of the sixteenth century, possibly after a storm had uprooted trees and exposed it. The material left a dark mark on whatever it touched, and shepherds are said to have used it to mark their sheep.

The substance was graphite, a form of pure carbon, but nobody at the time knew this. Because it looked and behaved rather like lead, it was called 'black lead' or 'plumbago', from the Latin word for lead. The confusion has lasted to the present day: the core of a pencil is still commonly called its 'lead', even though pencils have never contained the metal. The name 'graphite', from a Greek word meaning 'to write', was proposed only in 1789, by the German geologist Abraham Gottlob Werner.

The Borrowdale deposit was unusual. Graphite is normally found in small, crumbly lumps mixed with other minerals, but the graphite at Borrowdale was so pure and solid that it could simply be sawn into thin sticks. At first these were wrapped in string or sheepskin to keep the user's hands clean; later, craftsmen began to insert them into hollowed-out pieces of wood. The new tool had clear advantages over the quill pen, which had to be dipped in ink every few words: it was easy to carry, it could not spill, and its marks could be rubbed away.

Because it can withstand very high temperatures without melting, graphite soon proved valuable for other purposes too, notably for lining the moulds in which cannonballs were cast. As its value rose, theft became a serious problem, and in 1752 Parliament passed a law that made the stealing of graphite a serious criminal offence.

Because Borrowdale was the only known source of graphite of such quality, England enjoyed a near monopoly on good pencils for some two hundred years. Pencil-makers elsewhere tried to use the poorer, powdery graphite available to them, binding it with substances such as sulphur or glue, but the results were inferior. The breakthrough came from France. In the 1790s, during the wars between France and Britain, French supplies of English graphite were cut off, and the government turned to the inventor Nicolas-Jacques Conté for an alternative. In 1795 he patented a process in which powdered graphite was mixed with clay and water, pressed into rods and then fired in a kiln. The method had an important additional benefit: by changing the proportion of clay, manufacturers could control the hardness of the pencil. More clay produced a harder pencil and a paler line; more graphite produced a softer pencil and a darker one.

Conté's process, with refinements, is essentially the one still used today, and it allowed pencil-making to flourish wherever clay and ordinary graphite were available. In Germany, the city of Nuremberg, which had been a centre of the craft since the seventeenth century, became home to large pencil factories. In the United States, one unexpected contributor was the writer Henry David Thoreau, who worked in his family's pencil business in Concord, Massachusetts, and helped to improve its products by devising a better method of grinding graphite. In England, meanwhile, the Borrowdale mine was gradually exhausted, but the nearby town of Keswick, where a pencil factory had opened in the 1830s, remained a centre of production for well over a century.

Over the same period, the pencil acquired the features that are now taken for granted. Instead of being made one at a time by hand, pencils came to be produced in batches: machines cut grooves in a thin slab of wood, cores were laid in the grooves, and a second slab was glued on top before the 'sandwich' was cut into individual pencils. Many were given six sides, which stopped them rolling off sloping desks. Erasers, too, have a history of their own. Before the 1770s, people removed pencil marks with pieces of bread; then the English scientist Joseph Priestley noted that a piece of rubber could do the job, which is said to be how the material got its English name. In 1858 an American, Hymen Lipman, patented a pencil with a rubber attached to one end. His patent was later declared invalid, however, because the US Supreme Court decided that he had simply combined two existing objects rather than invented something new.