IELTS Academic Reading Practice Test 422

In the first decades of the twentieth century, driving after dark on a country road was an act of faith. Headlamps were weak, bends were unmarked, and the edge of the carriageway dissolved into the dark. A driver had little more than the white line, where one existed, to judge the shape of the road. Fog, rain and the glare of an approaching vehicle made matters worse. Councils in Britain were beginning to light main streets, but the thousands of miles of road between towns remained unlit, and the number of motor vehicles was rising quickly. The problem was not simply comfort. A car that left the road at night could easily overturn in a ditch or strike a wall.

Percy Shaw was born in Halifax, in the West Riding of Yorkshire, in 1890. He left school at an early age and made his living from road work, eventually running a small business as a contractor. That background gave him a practical familiarity with surfaces, drains and the habits of local authorities, though it gave him no training in optics. He was, by accounts, an observant and mechanically minded man who preferred to solve problems with his hands. The idea for which he became known came from a journey he made at night.

The story Shaw later told is that he was driving home in fog when he saw two small points of light ahead. They belonged to a cat sitting by the roadside, and they were the reflection of his own headlamps in the animal's eyes. The sight gave him the principle he needed: a surface that returned light to its source could mark the road even when the road itself was invisible. He is said to have experimented with mirrors and glass before settling on a simpler device. Whether or not the cat was exactly where legend places it, the account captures the essential insight, which was to use reflection rather than illumination.

The device he developed was a squat dome of rubber, set into a cast-iron base and fixed in the road surface. Two glass lenses were embedded in the dome, facing the traffic, and their shape threw light back towards the driver. The stud was low enough for a wheel to pass over it. This arrangement produced an unexpected advantage. When a vehicle pressed the rubber dome down, the lenses were pushed against the rubber housing; as the dome sprang back, the glass was wiped clean. Mud, grit and rainwater were shed in the same movement, so the reflector cleaned itself each time it was used. The base protected the mechanism and kept the stud upright under the weight of traffic.

Shaw applied for a patent in 1934 and set up a company, Reflecting Roadstuds, in Halifax. The early years were difficult. Local authorities were cautious, the cost of installing the studs along a road was not trivial, and many engineers doubted that a small piece of rubber and glass could survive heavy lorries. Only a modest number of councils placed orders, and the business remained small. Shaw continued to improve the design, but the market he needed did not yet exist.

The Second World War changed the situation. Blackout regulations required towns and cities to switch off street lighting, and drivers had to move in near-darkness. The risk of accidents rose sharply, especially at corners and junctions. Cat's eyes were already known to a few road engineers, and now they offered a way of marking a route without showing a light that an aircraft could see. Orders increased, and the studs were fitted on a large scale on roads used by the armed forces and by civil traffic. Production expanded, and the device began to be treated as a normal piece of road equipment rather than an experiment.

After the war, the studs spread further. As traffic volumes grew and new roads were built, highway authorities looked for cheap ways to make driving safer at night. Cat's eyes were laid at bends, junctions and pedestrian crossings, and along stretches of road where lighting was thought unnecessary or too expensive. In the late 1940s and 1950s they became a familiar feature of British roads, and other countries began to manufacture similar reflectors. The exact number installed is impossible to establish, but by the 1960s the studs were being produced in large quantities.

Later versions changed the materials but not the principle. Plastic bodies replaced cast iron in many designs, reducing weight and cost. The glass lenses were improved and eventually joined by microprismatic reflectors, which use a pattern of tiny facets to return light more efficiently. Some modern studs contain small solar panels and light-emitting diodes, so that they can glow without a passing headlamp; others are designed to be visible from a wider angle. Colour is now used to carry information: white studs usually mark the lanes of a carriageway, while amber, red and green may indicate junctions, lay-bys or the edge of the road. The self-cleaning rubber dome remains the basis of the classic design.

Shaw died in 1976. By then his invention was embedded in the everyday furniture of the road, too common to attract much notice. The company he founded continued to make road studs, and the cat's eye became a standard piece of road equipment in many countries. Its success rested on a simple observation: a driver does not always need more light, only something that will return the light already available.

A gecko can run up a sheet of glass, hang from a ceiling by a single toe and stop dead in the middle of a stride, and it does so without claws, glue or suction. The feat puzzled naturalists for centuries. Sticky secretions and tiny suction cups were both proposed as explanations, and both survived into the twentieth century. Neither is now accepted: geckos leave no trace on the surfaces they cross, and their grip does not weaken when the air is removed.

Under a microscope the underside of a gecko's toe turns out to be covered in rows of ridges, called lamellae. Each ridge carries a dense forest of microscopic hairs known as setae, and a single toe may hold hundreds of thousands of them. Every seta, in turn, splits at its tip into hundreds of still finer flattened structures, the spatulae, whose ends are only a few hundred nanometres across. The arrangement is a hierarchy of scales, and each level multiplies the surface available at the next. The final division is the important one, because it brings the animal into contact with the wall at the scale at which the physics of everyday objects gives way to the physics of molecules.

At separations of a few nanometres, all molecules attract one another weakly, a phenomenon known as the van der Waals force. It is far too feeble to hold anything of ordinary size, because two flat objects pressed together touch at only a handful of points. A gecko's pad, divided so finely, brings an enormous number of spatulae within range of the wall at the same time, and the combined attraction of all those tiny contacts is enough to support many times the animal's weight. In 2000 a team led by Kellar Autumn, a biologist then working at Lewis and Clark College in Oregon, measured the pull of individual setae and showed that the strength of the effect matched the predictions of van der Waals physics rather than those of suction or capillary action.

The force is not merely strong; it is controllable, which matters more. A seta grips when it is loaded in one direction, towards the gecko's body, and lets go when it is pulled at a steeper angle. Running therefore involves a deliberate sequence. The foot is placed flat and the toes spread and drag very slightly inwards to engage the hairs. To detach it, the animal curls the tips of its toes upward and peels the pad off the wall ridge by ridge, like a strip of tape lifted from a surface. Because the peeling needs only a fraction of the force that the whole pad can bear, the switch between grip and release takes milliseconds. High-speed filming has shown that a gecko running at speed takes more than a dozen steps a second.

Gecko feet also keep themselves unusually clean, which is essential for an adhesive used many times in a lifetime. Dust and sand do not accumulate on the pad. Particles that are picked up make contact with only a few spatulae, so the attraction they experience is small compared with the attraction between the pad and the wall, and they are shed at the next step. In experiments in which pads were deliberately coated with microscopic spheres, most of the grip returned after a few strides. Some surfaces, by contrast, defeat the gecko: on waxy leaves or very rough rock the pads make contact at far fewer points, and the animal slips.

Important questions remain. Water is one of them. A thin film of moisture on a surface might be expected to help adhesion, and some measurements do show grip rising sharply in very humid air, but other experiments have found the opposite, and the effect is still being argued over. The role of the hairs as sensors is also uncertain. The toe pads are supplied with nerve endings, and geckos may use them to judge a surface before committing their weight to it, though how much information they provide is unknown. Nor is it clear how the pads perform on the surfaces a wild gecko actually meets, since most measurements have been made on smooth glass or plastic.

The structure has attracted engineers since the 2000s, when several groups succeeded in making synthetic adhesives from silicone rubber moulded into microscopic pillars. The first demonstrations used pads no larger than a fingernail, and prototypes now include tapes, grippers for handling delicate components, and robots that climb vertical walls. Military research programmes have explored pads that would allow a person to scale a glass building. Manufacturers have experimented with other materials too, including carbon nanotubes, in the search for a surface that holds as firmly as a gecko's toe. Yet no artificial version matches the animal. Geckos manage their grip with muscles and nerves that keep the pad at the right angle and clean it as they walk, and synthetic materials clog with dust and lose their hold after repeated use. Rough surfaces, which the animal itself avoids where it can, remain a serious obstacle. For all that, the gecko's solution has already changed how engineers think about adhesion: the old assumption that a reusable adhesive must be soft and tacky like a plaster has given way to the idea that stiffness and structure can do the job better.

Few questions of educational policy attract as much passion as tuition fees. In much of Europe, university teaching is still provided without charge, and in a few countries students also receive grants towards their living costs. England, Australia and much of the United States take a different route: students pay substantial fees, usually borrowing the money from the state and repaying it from later earnings. The difference has consequences for who applies, who graduates and who carries the cost. It also produces a debate in which the two sides often talk past each other, because they are answering different questions.

Those who want tuition to be free for everyone begin from the idea that higher education is a public good. Some economists put the point in terms of benefits that spill over: a country with more graduates is more productive, collects more tax and has healthier citizens. The graduate captures only part of that return, the argument runs, so if students must pay the whole cost themselves they will invest less than is good for society. On this reasoning the cost should be met from general taxation, as it is for schools and roads. The same logic is used to justify free schooling for children, which no country now expects parents to buy.

A second group of economists accepts that such benefits exist but disputes the conclusion. Their concern is distribution. Because graduates earn, on average, considerably more than people who do not go to university, a policy that makes tuition free moves public money towards households that are already affluent. The children of professional families are far more likely to enter university than the children of manual workers, so much of the subsidy goes to the well-off. Estimates of the share vary, but all point in the same direction. In the blunt phrase used by some critics, free tuition is a benefit paid for by the poor and enjoyed by the rich.

Evidence about fees, however, is less alarming than either side sometimes claims. Several analyses of the sharp increase in English fees in 2012 found that the overall proportion of school-leavers entering higher education barely moved. What did fall was the number of mature and part-time students, a group that is sensitive both to cost and to the terms of the loans available to them. The lesson is not that fees are harmless but that they alter behaviour selectively, in ways that are easy to miss if only the headline figure is examined.

Surveys of prospective students point to something that a focus on fees obscures. What deters people from low-income backgrounds is often not the size of the debt itself but the fear of it, and the difficulty of covering rent, food and travel while studying. Living costs are the obstacle that students mention first. Debt is abstract and distant; next month's rent is neither. A system that charges no fees but offers no maintenance support may therefore do less for access than one that charges modest fees and provides generous grants.

Researchers who study access go further. They point out that the gap in participation between rich and poor is already wide by the age of eighteen, and that it is produced by differences in schools, in family resources and in the information available about university. Abolishing fees therefore cannot by itself widen participation; it removes one obstacle among several, and possibly the least important. Money spent on the early years, on teaching and on advice may do more to change who ends up in a lecture hall.

The supply side matters too. Where tuition is free but public funding per student is allowed to fall, universities have less to spend on staff, laboratories and small-group teaching. Many respond by capping the number of places. Such rationing tends to favour applicants with the strongest school records, who are disproportionately those from comfortable homes. Free tuition, in other words, can coexist with severe inequality of access if the system is starved of money. The result can be a system that is free and also deeply unequal, admitting mainly those whose families have already given them every advantage.

The strongest argument for universality is political rather than economic. A benefit that everyone receives builds a broad constituency and is difficult to remove, whereas a means-tested grant goes only to a minority who may lack the confidence to claim it. Defenders of free tuition argue that targeted support is always the first item to be cut in a budget crisis. A simple principle, they say, is easier to defend than a complicated scheme of loans and discounts.

None of this makes the arrangements in fee-charging countries satisfactory. My own view is that the case for universal free tuition is weaker than its supporters maintain, but the case for shielding students from the cost of living is very strong. A settlement that ignored the graduate's later earnings would be unfair to taxpayers who never went to university; one that ignored the student's daily needs would keep the door closed to the very people the policy is meant to help.

A sensible scheme would therefore ask graduates for a contribution that depends on what they actually earn and is repaid slowly, and would spend the money saved on maintenance grants. The question is not whether university should be paid for, but who should pay, when and how much.