IELTS Academic Reading full test 3

The pencil: a short history of an everyday tool

A Few objects are as familiar, or as overlooked, as the pencil. It is cheap, light and needs no power or ink, and a single pencil can draw a line many kilometres long. Yet the pencil has a surprisingly complicated history, involving a rare mineral, a wartime shortage and a great deal of experiment. Its story also shows how a simple product can depend on advances in chemistry and manufacturing that its users never notice. Behind every pencil lie decisions about which minerals to use, how finely to grind them, what kind of wood to choose and how to join the parts together so that the core does not break when the pencil is dropped.

B The story usually begins in the sixteenth century in Borrowdale, a valley in the north-west of England, where an unusually pure deposit of graphite was discovered. Graphite is a soft, dark form of carbon that leaves a mark when it is drawn across a surface. Local farmers are said to have used it to mark their sheep. At the time, nobody understood what the substance was, and because it looked rather like lead, it was often called 'black lead' or 'plumbago'. The name stuck: even today, people speak of the 'lead' in a pencil, although pencils have never contained the metal.

C The Borrowdale graphite was so pure that it could be cut into thin sticks and used directly. Because the sticks were soft and brittle and left marks on the user's fingers, they were first wrapped in string or cloth. Before long, craftspeople found a better solution: they placed the graphite inside a holder made of wood. The material became so valuable that the mine was guarded, and it was opened only for limited periods so that the supply would not run out too quickly. Graphite also had uses beyond writing, for example in the lining of moulds for casting metal, which made it even more important to those who controlled it. Pencils made in this way were prized by artists and writers across Europe, but because they depended on a single source, their price and supply were always uncertain.

D The most important change came in France at the end of the eighteenth century. At war with Britain, France could no longer import English graphite, and French pencil makers had to manage with poorer supplies that were full of impurities. In 1795, an engineer named Nicolas-Jacques Conté developed a method of grinding graphite into a powder, mixing it with clay and water, shaping the mixture into thin rods and firing them in a kiln. This process had two great advantages. It allowed pencils to be made from lower-quality graphite, and it allowed makers to control how hard or soft a pencil was simply by changing the proportion of clay. More clay produced a harder pencil and a lighter line; more graphite produced a softer pencil and a darker line.

E Conté's method is still the basis of pencil making today, and it explains the grading systems printed on many pencils. In one common system, 'H' stands for hardness and 'B' for blackness, so a 4H pencil makes a fine, pale line suited to technical drawing, while a 6B is soft and dark and is popular with artists. HB sits in the middle. Manufacturers do not all use exactly the same mixture, so an HB pencil from one company may be slightly darker or harder than an HB pencil from another. The wooden casing also changed. Makers searched for timber that was soft enough to sharpen easily but strong enough not to split, and cedar became a popular choice. Other features were added over time. Many pencils were made with six sides, which makes them comfortable to hold and stops them from rolling off a sloping desk. In 1858, an inventor in the United States was granted the first patent for a pencil with an eraser attached to one end, an idea that quickly spread, although many artists still prefer pencils without one.

F Despite the arrival of pens, keyboards and touch screens, the pencil has not disappeared. Builders and carpenters use it because its marks can be made on wood and easily removed; students use it in tests that are marked by machine; and artists value the range of tones that different grades can produce. Perhaps its greatest strength is that it forgives mistakes. A pencil line can be rubbed out and drawn again, which may be one reason why so many people still reach for one when they begin to plan, sketch or think.

Finding longitude: the clock that changed navigation

A For centuries, sailors crossing open water faced a dangerous gap in their knowledge. They could work out how far north or south they were, their latitude, fairly easily by measuring the height of the sun at midday or of certain stars at night. Their east-west position, or longitude, was another matter. Without it, a ship's crew could not be sure how far they had travelled across an ocean, and ships ran short of food and water while searching for land, or struck rocks they believed were many kilometres away. Navigators did their best with a technique called dead reckoning, in which they estimated their position from their speed, their direction and the time that had passed. Speed was measured by throwing a piece of wood attached to a knotted rope over the side and counting how many knots ran out in a set time. Errors in each of these measurements added up day after day, however, so that after several weeks at sea a ship's estimated position could be very far from its true one. As sea trade grew, the loss of ships, cargo and lives made the problem a matter of national concern for seafaring countries.

B In theory, the solution was well understood. The Earth turns through 360 degrees in 24 hours, or fifteen degrees every hour. If a navigator knew the exact time at a home port and could compare it with the local time on board, measured from the position of the sun, the difference would give the ship's longitude. A difference of one hour meant fifteen degrees east or west of home. The difficulty was practical: no clock of the time could keep accurate time on a moving ship. Pendulum clocks, which worked well on land, were thrown off by the rolling of the waves, and changes in temperature and humidity made metal parts expand, contract and rust.

C Many scientists believed that the answer lay in the sky rather than in machinery. Their proposal, known as the lunar distance method, used the moon as a kind of clock in the heavens. By measuring the angle between the moon and particular stars, and comparing it with tables calculated in advance, a navigator could work out the time at home. The method was sound, but the tables took years of careful observation to prepare, and the measurements and calculations on board could take several hours, even for a skilled officer.

D In 1714, the British Parliament offered a large prize for a practical way of finding longitude at sea, and set up a group of experts to judge the entries. Among those who took up the challenge was John Harrison, a carpenter and self-taught clockmaker from the north of England. Harrison had no university education, but he had already built wooden clocks that were remarkably accurate. Over more than thirty years, he designed a series of sea clocks, solving one problem after another: he used materials that did not need oil, combined metals that responded differently to heat so that their changes cancelled out, and found ways to keep the mechanism steady as the ship moved. Each new clock took him years to build and test, and he often abandoned a design that worked reasonably well because he had thought of a better one. His supporters admired his patience, but others saw the long delays as a sign that a mechanical solution would never be practical.

E His most famous design, completed in 1759, looked less like a ship's clock than a large pocket watch. On a voyage from England to the Caribbean in the early 1760s, it lost only a few seconds over many weeks at sea, an accuracy far beyond what most experts had thought possible. A second trial confirmed its performance. Even so, the judges, several of whom were astronomers who favoured the lunar method, were slow to accept the result. They demanded further tests and asked Harrison to explain his design in detail and to have copies made by other craftsmen. He received most of the prize money only late in his life, after the King himself took an interest in his case.

F At first, sea clocks of this kind, known as marine chronometers, were too expensive for most ships, and many navigators continued to rely on lunar distances. Over the following decades, however, other makers simplified Harrison's ideas, and chronometers became more affordable and reliable. By the nineteenth century, a well-equipped ship might carry two or three, so that their readings could be checked against each other. Today, satellites have replaced both methods, but the principle that a precise clock can tell you where you are remains at the heart of modern navigation systems.

The Rosetta Stone and the reading of hieroglyphs

A For more than three thousand years, the people of ancient Egypt recorded the names of their kings, their prayers and their laws in hieroglyphs, a script made up of hundreds of small pictures of birds, people, plants and everyday objects. By the late fourth century AD, however, the script had stopped being written, and within a few generations nobody could read it. For more than a thousand years afterwards, travellers and scholars admired the carvings on temples and monuments without understanding a word. Many of them believed that each picture stood for an idea rather than a sound, and that the script was a kind of secret symbolic code. This belief, as it turned out, was a major reason why early attempts to read the inscriptions failed.

B The breakthrough began with a chance discovery. In 1799, during the French military campaign in Egypt led by Napoleon Bonaparte, soldiers rebuilding an old fort near the town of Rashid, known to Europeans as Rosetta, uncovered a large broken slab of dark stone covered in writing. The slab carried the same text three times, in three different scripts: hieroglyphs at the top, demotic (a later, everyday Egyptian script) in the middle, and ancient Greek at the bottom. Because scholars could still read ancient Greek, they immediately understood the importance of the find. The Greek section revealed that the text was a decree issued by a council of priests in 196 BC in honour of King Ptolemy V.

C The stone did not stay in French hands for long. After British forces defeated the French army in Egypt, the stone was handed over under the terms of the French surrender in 1801 and shipped to London, where it has been on display in the British Museum since 1802. By then, however, scholars who had travelled with the French expedition had already made copies of the inscriptions, and further copies were soon circulating in Britain. As a result, researchers in several countries could work on the texts without ever seeing the stone itself. Their task was not easy: the top of the stone had broken off, so much of the hieroglyphic section was missing.

D One of the first people to make real progress was Thomas Young, an English scientist already well known for his work on light. Some groups of hieroglyphs on the stone were surrounded by an oval line, now called a cartouche, and earlier scholars had already suggested that these groups contained the names of kings. Building on this idea and comparing the cartouches with the Greek text, he worked out which group spelt the name Ptolemy and gave sound values to several of its signs, some of them correctly. Young also recognised that the demotic script was related to the hieroglyphs. However, he believed that sound signs were used mainly to write foreign names, such as Ptolemy, which was Greek, and that the rest of the script worked in a different, symbolic way.

E The decisive step was taken by the French scholar Jean-François Champollion. From an early age, Champollion had studied many languages, including Coptic, the latest stage of the Egyptian language, which was written in an alphabet based on Greek. Working with the Rosetta Stone and copies of inscriptions from other monuments, he compared the cartouches of Ptolemy and Cleopatra, two names that share several sounds, and confirmed the values of many signs. He then went further than Young. Using his knowledge of Coptic, he was able to read the names of earlier Egyptian kings, such as Ramesses and Thutmose, which showed that sound signs were also used to write Egyptian words, not only foreign ones. In 1822 he set out his findings in a letter that was soon published, and this is generally regarded as the moment when hieroglyphs were deciphered.

F Champollion's work showed that hieroglyphic writing is a mixed system. Some signs stand for sounds, either a single consonant or a group of consonants; others stand for whole words; and some, known as determinatives, are not pronounced at all but show the general category of a word's meaning, for example whether it refers to a person, a place or an action. Vowels were generally not written, which is why modern scholars cannot be certain exactly how many Egyptian words were pronounced. Champollion died only ten years after his discovery, but others continued his work, and today specialists can read most surviving texts. The stone itself has become so famous that its name is now used in English for anything that provides the key to understanding a difficult problem.