IELTS Academic Reading Practice Test 410

Self-service grocery retailing is barely a century old, yet it created a difficulty that its pioneers had not anticipated. Customers who selected their own merchandise had to convey it to the checkout, and the wire hand baskets supplied by stores became painfully heavy long before they were full. Sylvan Goldman operated a chain of grocery stores in Oklahoma City trading under the name Humpty Dumpty. He noticed that shoppers tended to cease purchasing once their baskets grew heavy, and that they then joined the queue at the till instead, a habit that cost him considerable business. In 1937 he resolved to remove the limitation that a pair of human arms imposed on the size of a household's purchase.

The solution, he subsequently explained, derived from a folding wooden chair in his office: if a basket were mounted on a chair that rolled, the customer would not have to lift it at all. Goldman sketched a frame that opened in the manner of such a chair, accommodating one basket above and a second below. He then took the drawing to a mechanic in his employment, Fred Young, who built a working model. The frame was constructed of steel and ran on four small casters; when empty it folded flat, so that a row of them could stand against a wall without obstructing the aisle.

The first trolleys appeared in Goldman's stores in 1937 and carried two wire baskets, the lower one intended for heavy goods such as bottles and tins. The wheelbase was sufficiently narrow to pass between counters. In its essentials the apparatus was already complete: a rigid frame on casters, baskets at waist height and a handle by which it was propelled.

Customers, however, proved reluctant. Women informed his staff that pushing a trolley made them feel as though they were wheeling a pram through the shop, while men considered the device undignified and refused to be seen with one. Some shoppers filled a trolley and then abandoned it in an aisle; takings did not increase, and Goldman was urged to abandon the experiment.

His response was theatrical, and it succeeded. He hired men and women to push trolleys about his stores and pretend to shop, and stationed a greeter at the door to hand each customer a trolley and explain its use. The demonstrations continued for weeks, and once shoppers saw others using the trolleys without embarrassment the resistance faded. What had looked eccentric became ordinary, and within a few months the trolleys were in constant use.

Goldman moved to protect the design, applying for a patent in 1939 and receiving one in 1940. Because his own stores could not keep a factory busy, he established a separate company to manufacture trolleys for other grocers. The folding carrier was soon sold to chains across the United States, so that a solution to one retailer's difficulty became a commercial product.

The trolleys had one obvious defect: they consumed space. A hundred of them standing open would fill a small stockroom, and employees had to return them to the entrance individually. In 1946 a grocer in Kansas City named Orla Watson designed a trolley whose rear panel hinged upwards. With the panel raised, one trolley could be pushed into the one ahead until a row of them nested together like spoons. Watson was granted a patent for the telescoping trolley in 1949, and a dispute over priority followed. Every large manufacturer nevertheless adopted the principle, which is why a supermarket can store a hundred trolleys in the space formerly occupied by ten.

Later changes were matters of scale and material rather than of principle. On many models wire gave way to plastic, which is lighter, cheaper and less likely to scratch a car in the car park, and baskets grew deeper as a weekly shopping trip replaced the daily visit. In parts of Europe a coin-operated lock was fitted to the handle so that customers would return their trolleys. Some modern trolleys carry a braking wheel that locks when the trolley crosses a wire buried at the edge of the car park.

The effect on retailing was considerable. By transferring the work of carrying from the customer to a machine, the trolley helped to make the supermarket the dominant form of food shop in the industrialised world. Because a customer could transport a week's supplies without effort, stores could be built larger and further from home, and the range of goods they stocked could expand accordingly. The trolley also altered what people purchased, since a shopper pushing one passes the shelves slowly and can be tempted by products that a person carrying a basket would not stop for. Aisles had to be widened so that two trolleys could pass one another. Checkouts, too, were rebuilt to take a loaded trolley rather than a basket.

Goldman died in 1984, by which time the object he had improvised from a folding chair had become too familiar to be noticed. It is easy now to overlook how strange the first trolleys must have looked, and how stubbornly customers resisted them. The trolley is a rare kind of invention: not a machine that does something new, but one that removes a single physical constraint. In removing that constraint it altered where people shopped, how much they carried home and, ultimately, the appearance of the modern supermarket.

Sand dunes are among the most mobile features of the Earth's surface. A dune is simply a mound of loose sand built by the wind, but the largest fields of them, which geomorphologists call sand seas, cover hundreds of thousands of square kilometres in the Sahara and in central Asia. Smaller dunes fringe many coastlines, where they form a low barrier between beach and land. Because dunes are made of material that the wind can pick up and put down again, they are never finished objects; they grow, shift and disappear on timescales that people can watch.

Three conditions are needed for dunes to form: a supply of loose, dry sand, a wind strong enough to move it, and a surface on which the sand can settle. Wind alone tends to spread grains evenly, so a dune usually begins where something interrupts the flow. A rock, a bush or a fence slows the air immediately around it, and the grains it was carrying fall out. Once a small heap exists, the heap itself becomes an obstacle: the wind is slowed on its sheltered side, more sand is deposited, and the mound grows. Geomorphologists describe this as a positive feedback, in which each addition makes the next more likely.

Sand travels in three ways. The largest grains, too heavy to be lifted, roll or shuffle along the surface, a process called creep. The middle-sized grains, which make up most of a dune, leave the ground in short hops, rising a few centimetres and landing perhaps a metre away before bouncing again. This is saltation, and it accounts for most of the sand moved in deserts. The finest material, silt and clay, can be held in the air for long distances as suspension, and dust from the Sahara is carried across the Atlantic to the Americas.

Downwind of a growing mound the shape becomes asymmetric. On the windward side the slope is gentle, typically between five and fifteen degrees, and grains are pushed steadily upwards. At the crest they lose the shelter of the slope, tumble over the edge and slide down the leeward face.

That face is steepened by avalanches until it stands at the angle of repose, the angle at which dry sand can no longer hold itself, usually between about thirty and thirty-four degrees. The dune is thus constantly eroded on one side and rebuilt on the other, and the whole mass migrates. Most dunes advance only a few metres a year, though faster rates are measured in exposed places.

The shape a dune takes depends on the winds that build it and on how much sand is available. Barchans are crescents, formed where sand is scarce and the wind blows mainly from one direction; their horns trail downwind, and they can travel faster than more massive forms because they are smaller. Where two winds blow at an angle to one another, long ridges called linear dunes develop, running parallel for many kilometres. Star dunes, with several arms radiating from a central peak, are built where the wind changes direction through the year. They grow slowly, and because their sand is held in several directions at once, they move very little.

Coastal dunes form differently, because plants take part. Marram grass, which grows on the dunes of north-west Europe, tolerates burial and salt spray, and its long roots and creeping stems bind the sand. Vegetation slows the wind at ground level and traps grains, so a foredune builds up just behind the beach. As the dune grows, other plants colonise it, lichen and moss spread over the surface, and a grey, more stable dune develops behind the yellow one. The stability is not absolute: if the cover of plants is broken, the wind finds a gap and a blowout begins.

Human activity is the usual reason for that break. Grazing animals, fires and vehicles driven across dunes strip vegetation, and dunes close to growing towns may be cleared for building or mined for sand. Once sand is on the move, roads, irrigation channels and farmland can be buried. Sand fences and the planting of drought-tolerant grasses are the standard remedies, and large shelter-belt programmes in northern China have been planted to slow the advance of sand. Such measures work where they are maintained, but they are expensive and vulnerable to drought.

Several questions remain open. The most basic is how a dune starts. Some researchers treat each dune as the result of an obstacle that collects sand; others argue that a flat bed of sand is itself unstable in a strong wind, so that regular patterns emerge without any obstruction. Both effects are probably real, and their relative importance is disputed. Forecasting how quickly dunes will migrate is also difficult, because the rate depends on wind, sand supply and the shape of the dune, all of which change, and because a long-term average may hide a few storms that do most of the work.

Dunes matter for more than their movement. The sand fields of arid regions are a major store of the dust that fertilises parts of the ocean, and coastal dunes protect low land from storms while providing a habitat for specialised plants. They also act as groundwater reservoirs. None of this is compatible with treating a dune as a fixed landscape: it is a system that is always in transit, and managing it means managing that motion rather than attempting to stop it.

Britain once required every dog owner to buy a licence, and it no longer does. The duty was introduced in 1867 and abolished in 1987, by which time the fee raised less than the cost of collecting it. Since then the only universal obligation on owners in England has been microchipping, compulsory for dogs since 2016 and for cats since 2024. Animal welfare organisations, however, continue to argue that ownership of any animal should require a licence, and their case deserves to be taken seriously rather than dismissed as bureaucracy.

The argument for licensing rests on identification. A register would tell the authorities who is responsible for a particular animal, which would make it easier to reunite lost pets with their owners and much harder for someone to abandon an animal without being traced. Supporters also maintain that a fee would make people think twice before acquiring an animal on impulse, and that the money raised could pay for the inspections that animal welfare laws currently lack. In their view, a licence converts a private hobby into a public responsibility.

Critics reply that a fee charged to every owner would place the greatest burden on the poorest households, in which the companionship of an animal may matter most. A licence, they add, would be obeyed by the conscientious and ignored by everyone else. Those who treat animals badly are the least likely to register at all. Paying a fee, moreover, demonstrates nothing about how an animal will be treated; it records only that the owner has paid. A register built in this way would describe the responsible majority and miss the people it was meant to catch, while the cost of chasing the rest would fall on inspectors who are already few in number.

The British experience is instructive. The 1867 licence was widely evaded and produced little revenue; evasion was never seriously punished, and the certificate was eventually worth so little that abolition cost nothing politically. What replaced it, in effect, was a different kind of record. The microchip databases that now hold the details of millions of dogs provide much of what a licence would deliver — a name, an address, a link between animal and owner — without a fee or a certificate, and it is not obvious what a licence would add to them.

Other countries show a similar pattern. Several European states levy an annual tax on dog ownership, and some municipalities register animals in connection with rabies vaccination. German municipalities, for example, levy a local dog tax, and registration of the animal forms part of the same system. Where registration is combined with a service that owners value, compliance tends to be high; where it is merely a charge, it tends to be low. This suggests that the design of a scheme matters more than its existence. A licence attached to nothing but a receipt is a tax, whereas a licence attached to vaccination, microchipping and inspection is a service.

Economists have long pointed out that a charge can change behaviour in two directions at once. Set low, it is easy to collect and does nothing; set high, it discourages ownership among exactly the people least able to pay, and encourages evasion. A charge set at the level of the real cost of inspection is a different proposition from one whose purpose is chiefly to raise revenue. There is little evidence that charging owners reduces the number of unwanted animals, though there is good evidence that animals which are identified, vaccinated and regularly seen by a vet are less likely to end up in a shelter. The case for a licence therefore turns on administration, not on principle.

A different proposal attracts some animal welfare researchers: that the licence should be earned rather than bought. First-time owners would attend a short course or pass a simple test on an animal's needs before acquiring it. The idea has obvious appeal, since many welfare problems arise from ignorance rather than cruelty. Yet such schemes have rarely been evaluated, and a test taken once, possibly years before an animal arrives, guarantees very little. I would not object to a trial, but I would not expect it to transform welfare on its own.

My own view is that a licence for every owner is too blunt an instrument for the problem. It would impose a uniform burden on households whose circumstances differ enormously, and it would consume in administration money that could be spent on inspection. The real gaps lie elsewhere. Breeders and dealers, who produce and sell large numbers of animals, are barely regulated in some countries, and households that keep dozens of animals receive far less scrutiny than the family with a single dog. A breeder who sells hundreds of animals a year influences welfare far more than a thousand households that keep one animal each. Licensing should follow concentration and commerce, not affection.

The question, then, is not whether owning an animal carries obligations — it plainly does, and the law already imposes several — but which obligations are worth enforcing, and how. A licence that is not enforced offers an illusion of control, and an illusion is worse than an acknowledged gap, because it persuades everyone that something is being done. Identification, inspection and the regulation of those who trade in animals would do more for animal welfare than a certificate in every household.