IELTS Academic Reading Practice Test 41

Before the middle of the nineteenth century, tall buildings were not simply inconvenient to use; they were widely regarded as unsuitable for anyone except the young and the fit. Staircases limited practical commercial and residential space to roughly five or six storeys, and in many urban buildings the upper floors were occupied by workshops, storage rooms or poorer tenants rather than by wealthy customers.

Hoisting machines already existed, but they were used mostly in warehouses, mines and factories to lift goods rather than people. The reason was simple: if the rope or chain supporting a platform broke, the platform would crash to the bottom. For freight this risk was acceptable. For passengers it was not, and property owners were understandably reluctant to install a device that might suddenly drop their tenants or customers down a shaft.

Elisha Graves Otis was an unlikely figure to change this. Born in 1811 on a farm in Vermont, he tried a series of occupations, including carpentry, wagon building and running a gristmill, before becoming a master mechanic. In the early 1850s he was working at a bedstead factory in Yonkers, New York, where he needed a hoist to move heavy machinery and timber between floors. He was not attempting to invent the elevator; hoists had existed for centuries in various forms, from simple rope drums to geared platforms. His concern was safety, and he began experimenting with a device that would hold a platform in place if its lifting rope snapped.

The mechanism he built was simple and ingenious. A heavy wagon spring was attached to the lifting cable, and when the cable was taut the spring was pulled upward, holding a pair of toothed bars away from iron guide rails on either side of the shaft. If the rope broke, the tension disappeared, the spring released, and the teeth snapped into the rails. The platform would drop only an inch or two before catching firmly. Otis called his invention a safety hoist, and he installed it in the factory where he worked. It was a practical solution to a problem that had frightened building owners for decades, and it required no specialised materials or skilled maintenance.

Otis realised that the best way to sell his device was to demonstrate it in public. At the Exhibition of the Industry of All Nations, held in New York in 1854, he stood on an open platform that had been raised high above the audience. While a crowd watched, he ordered an assistant to cut the only rope holding the platform. The platform fell a few inches and then stopped. Reportedly, Otis called out that all was safe. The spectators, who had expected a crash, were astonished. The event gave the safety elevator a reputation it had previously lacked, and from that moment the idea of carrying people vertically began to seem possible rather than reckless.

The first passenger elevator to be installed in a commercial building was put into service in 1857 at the E. V. Haughwout store on Broadway in New York, a five-storey emporium selling china, glass and silverware. The elevator was steam powered and moved slowly, but it proved that customers would use a vertical lift if they trusted it. Within a few years, hotels, department stores and office buildings began to include elevators in their designs. Upper floors, which had once been the cheapest and least desirable space because they required climbing stairs, became the most valuable. Landlords could ask higher rents for rooms far above the street, and the economics of the tall building were reversed.

The effect on architecture was profound. As reliable passenger elevators spread, the traditional limit of five or six storeys no longer applied. Architects could plan buildings of ten, twelve or more floors without worrying that the upper levels would be unrentable. Much taller buildings became possible, though the elevator did not create the skyscraper by itself; steel-frame construction and improvements in fire safety, plumbing and heating were equally necessary. Yet without a safe way for people to reach the upper floors quickly, tall buildings would have remained impractical. The elevator made vertical cities thinkable, and the modern skyline began to emerge.

The technology continued to evolve through the late nineteenth century. Otis's original steam-powered machines gave way first to hydraulic systems and then, around the end of the century, to electric motors. Electric elevators could travel faster and did not require a steam engine or boiler, which made them suitable for very tall buildings. Automatic doors, push-button controls and level indicators were added over time, but the essential safety principle remained the same as Otis's wagon spring and toothed rails. Modern elevators still use mechanical brakes that engage if the car moves too quickly or the cables lose tension, and regular inspections keep the braking systems reliable.

Otis did not live to see the full transformation. He died in 1861, but his sons kept the company going, and the family name became one of the best known in the world of vertical transport. The safety elevator changed more than the skyline. It altered everyday expectations about where people could live, work and shop. It made high-rise housing possible, encouraged the central business district, and helped create the dense modern metropolis. Otis's achievement was not the elevator itself, but the trust that allowed millions of people to step into a small room and rise safely into the air.

Earthquakes are among the most destructive natural events, yet they remain remarkably difficult to anticipate. The basic cause is understood: stress accumulates along faults as tectonic plates move, and when the rock finally slips, stored energy is released as seismic waves. However, the exact time at which a particular fault segment will break cannot be known in advance with any useful precision. Seismologists therefore distinguish between prediction, which would state the time, place and magnitude of a specific earthquake before it occurs, and forecasting, which gives a general probability that an earthquake of a given size will occur in a region over a longer period.

For decades, researchers sought reliable precursors for prediction. They examined changes in water levels, radon concentrations, ground tilt, electrical conductivity and the behaviour of animals, hoping to find a signal that always preceded a large earthquake. Foreshocks, small earthquakes that sometimes come before larger ones, received particular attention. Some observations were suggestive, but no method proved consistent, and several apparent patterns disappeared when tested more rigorously. The Parkfield experiment in California, which began with a prediction that a magnitude six earthquake would occur on a specific segment of the San Andreas fault before 1993, illustrates the difficulty. The expected earthquake arrived more than a decade late and without the expected precursors.

Modern seismology has largely abandoned the ambition of short-term prediction and focuses instead on probabilistic forecasting. Seismic hazard maps estimate the likelihood that ground shaking of a certain strength will occur within a given number of years. These maps are based on the historical record, geological evidence of past earthquakes and measurements of how fast faults are moving. They cannot say that an earthquake will happen on a particular day, but they allow engineers to design buildings, bridges and pipelines for the shaking that is expected over their lifetime. Probabilistic forecasts are therefore central to building codes and land-use planning.

One influential idea in forecasting is the seismic gap hypothesis. This states that sections of a fault that have not ruptured in a large earthquake for a long time are more likely to do so in the near future, because stress has been building up while neighbouring segments have already slipped. The concept is appealing and has guided some regional risk assessments. However, its record is mixed. Not all identified gaps have produced large earthquakes within the expected periods, and major earthquakes have sometimes struck outside the gaps. The hypothesis remains useful as a way of ranking risk, but it is not a precise tool.

The most famous apparent prediction success came in China in 1975, when a magnitude 7.3 earthquake struck the city of Haicheng. Officials had ordered an evacuation after a series of foreshocks and unusual animal behaviour, and it is often said that the evacuation saved many lives. However, the event is less reassuring than it first appears. The earthquake followed a swarm of small tremors that acted as a natural warning, a pattern that does not occur before every large earthquake. Only a year later the Tangshan earthquake, which killed hundreds of thousands of people, struck in the early morning with no recognised warning. Haicheng was therefore not evidence that prediction is generally possible.

Earthquake early warning is sometimes confused with prediction, but the two are distinct. Early warning systems rely on the fact that seismic waves travel at different speeds. The first waves to arrive, called P waves, are usually weak and cause little damage. The more destructive S waves and surface waves follow. Instruments near the source detect the P waves, estimate the earthquake's location and size within seconds, and send alerts before the stronger shaking arrives. Systems in Japan, Mexico and the west coast of the United States can provide seconds to tens of seconds of warning. That may be enough to stop trains, shut gas valves, or allow people to move to a safer place.

Communication of risk is as important as the science itself. The Italian city of L'Aquila provided a painful example in 2009, after months of small earthquakes had worried residents. A government commission met and gave broadly reassuring messages, partly because scientists cannot reliably say that a swarm will lead to a large event. Six days later a magnitude 6.3 earthquake killed over three hundred people. Some scientists and officials were initially convicted of manslaughter for having given false reassurance, but most were later acquitted on appeal. The case showed that statements about uncertainty can be disastrous when they are misunderstood as promises of safety.

Most experts now argue that the most effective approach combines long-term hazard assessment, early warning, strict building codes and public education. Scientists cannot predict earthquakes with the precision that weather forecasts achieve for a storm, and pretending otherwise would be dangerous. Instead, the goal is to reduce risk: to know where strong shaking is likely, to make structures resistant to it, and to provide seconds of warning when an earthquake has already begun. Prediction may remain out of reach, but effective preparation is not.

Few workplace maxims are repeated as confidently as the claim that doing several things at once saves time. Busy employees answer emails while sitting in meetings, check messages during meals, and switch between documents, calls and spreadsheets throughout the day. The term multitasking is borrowed from computing, where a processor appears to run several programs simultaneously. For human beings, however, the comparison is misleading. Research has shown that the brain is not built to perform two demanding tasks at once. What feels like simultaneous activity is usually rapid switching from one task to another, and that process carries a cost.

The reason lies in the architecture of attention. The mind has a limited capacity for conscious processing, and a central control system must select which task will receive priority. When two tasks require conscious thought, they compete for the same mental resources. The brain can alternate between them, but it cannot give both full attention at the same moment. This limitation applies especially to tasks that involve understanding language, making decisions, planning or remembering. Tasks that draw on the same limited mental resource interfere with one another, so performance on one or both inevitably deteriorates.

Laboratory experiments confirm this. When volunteers are asked to switch between different activities, they respond more slowly and make more errors than when they complete the same tasks one after another. Even brief interruptions produce measurable costs, because the brain must disengage from one set of rules, activate a new set, and then return to the first while rebuilding the thoughts that were active. The delay is often only a fraction of a second, but repeated many times during the day it can amount to a substantial loss. The more complex and unfamiliar the tasks, the greater the penalty.

Studies of heavy media multitasking, such as using several screens or social platforms at once, have found that habitual multitaskers often perform worse on tests of working memory and distraction control. Some researchers have suggested that this may be because they become less able to filter irrelevant information. However, the evidence is not entirely consistent, and it does not prove that multitasking causes these weaknesses. It is equally possible that people with poorer attention control are drawn to more media activity. What the research does show is that simultaneously attending to several information streams rarely improves performance.

There are exceptions. Activities that have been practised until they are automatic, such as walking or riding a bicycle, require very little conscious attention and can occur alongside other tasks at little expense. This is why people can walk and talk, or cook a familiar recipe while listening to the radio. But even apparently simple combinations can become dangerous when one task suddenly demands control. Driving illustrates the point. Studies have found that conversations on a hands-free mobile phone still reduce the driver's awareness of the road, because language and spatial attention compete for the brain's executive control.

Neurological studies point to the prefrontal cortex, the part of the brain involved in planning and goal-directed behaviour. This region appears to hold one goal at the forefront of attention at a time. When a new goal arrives, the old one must be set aside, and the brain must reconfigure its activity. Brain imaging shows that switching between tasks activates a network of areas involved in attention and self-control. The cost observed in experiments is thus not a flaw in human effort; it is a fundamental property of how the brain manages conscious thought.

In workplaces, the myth of multitasking often leads people to keep email and messaging windows open while doing analytical work. Many workers report feeling busy but accomplishing less, and studies in occupational settings have linked frequent interruptions to higher stress and lower productivity. Open-plan offices and instant communication can make sustained attention difficult, but the solution is not to demand faster switching. Some companies have introduced periods without messages or meetings, allowing employees to focus on a single complex task without interruption. Observational studies indicate that after an interruption, workers often take several minutes to resume the original task, and some tasks are never resumed at all.

Laboratory work on the psychological refractory period provides further evidence of a processing bottleneck. When two tasks are presented close together, the second response is delayed, even when the tasks are simple. This delay suggests that the brain cannot select two responses at exactly the same moment. Although the delay is small, it compounds during repeated switching. The bottleneck can be reduced when one task becomes automatic, but it cannot be eliminated by effort alone. Such findings support the idea that multitasking is, for conscious tasks, a form of rapid serial processing rather than true parallel performance.

The conclusion seems clear. For demanding cognitive work, multitasking is largely an illusion, and the attempt to do several things at once usually produces slower, poorer results. The most effective approach is to give full attention to one task at a time, to group similar small tasks together rather than responding to them as they arrive, and to protect periods of uninterrupted concentration. Multitasking is not a desirable skill that some people have mastered; it is a common habit that most of us would benefit from abandoning for the work that matters most.