IELTS Academic Reading Practice Test 476

Anyone who approaches Djenné sees the mosque long before reaching the town. Its three towers, crowned with cones of mud and topped with ostrich eggs, rise above a flat plain of pale earth beside the Bani, a tributary of the Niger. For several centuries Djenné was one of the great market towns of the western Sudan, where salt carried across the Sahara was exchanged for gold, grain and cloth. The town also became a centre of Islamic scholarship, attracting teachers and students from across the region.

According to local tradition, the first mosque on the site was built in the thirteenth century by Koy Konboro, the ruler of Djenné, who converted to Islam and gave up part of his palace for a place of prayer. However much of the tradition is literally true, a substantial mosque is known to have stood in the town by the fourteenth century, when Djenné was at the height of its wealth. Responsibility for maintaining the building was shared among the leading families, and the ruler himself was expected to contribute.

Nothing of that first mosque survives above ground, and what is known of it comes from descriptions written by visitors and from the shape of the site. It appears to have been a large rectangular building of mud brick, strengthened by rows of buttresses. Mud was the obvious material: the floodplain offered no stone and little timber, but it did provide clay, straw and the husks left after rice had been harvested, which could be mixed with water and dried in the sun.

In the early nineteenth century Djenné was conquered by Sekou Amadou, the ruler of a Muslim state based to the west, who objected to the town's religious practices and to the decoration of its mosque. He had the building closed and left to fall into decay, and prayer was transferred to a plainer structure nearby. By the time French forces occupied the town at the end of the nineteenth century, much of the mosque had collapsed.

The building that stands today was completed in about 1907, more than a decade after the French had taken control. It was raised on the old foundations and followed the general form of its predecessor, but on a larger scale, with a platform of earth roughly three metres high to lift the prayer hall above the flood water of the rainy season. The work was carried out by the town's own masons, and it is often described as one of the finest examples of the Sudano-Sahelian style of architecture.

The fabric of the mosque is almost entirely earth. Bricks are formed by hand from a mixture of mud, water and rice husks, pressed into wooden moulds and left to dry in the sun; they are then laid in thick walls that taper towards the top. Rows of wooden beams, known locally as torons, are built into the walls and stick out about half a metre. They are not merely decorative: they serve as permanent scaffolding, allowing plasterers to climb the walls without erecting anything. The three towers on the wall that faces Mecca are the tallest part of the structure, and the white ostrich eggs on their summits are a traditional sign of purity.

The survival of the building depends on an annual ritual of repair. Each year, before the rains arrive in the middle of the year, the whole structure is given a new coat of plaster. Work begins weeks in advance, when mud is dug from pits outside the town and mixed with water and chopped straw in shallow basins. Women and girls carry water from the river, while men and boys tread the mixture and leave it to stand until it is smooth. Rice husks left over from the harvest are added to make the plaster lighter.

On the day of the plastering, which usually falls in April or May, much of the town gathers in the streets around the mosque. Drummers set up their instruments in the square, and the young men of each quarter compete for the honour of being first to reach the walls with a bowl of mud. The mud is passed up ladders and along the projecting beams, and a mason, working by eye and by long experience, spreads it over the surface. Finally the fresh plaster is smoothed with the flat of the hand so that it dries evenly. The work must be finished in a single morning, because the plaster hardens quickly in the heat.

The knowledge required to keep the mosque in repair belongs to a hereditary guild of masons, whose families have worked on the building for generations. Boys begin as apprentices, carrying water and mud, and learn by watching. There are no written plans, and the proportions of the building are remembered rather than measured. The guild also decides when the annual plastering will take place, in consultation with the town's religious leaders.

Because of the mosque, and the old town around it, Djenné attracts visitors from many countries, although people who are not Muslims are generally not admitted to the interior of the building. International recognition came in 1988, when the old town was inscribed on the World Heritage list. In 2016, however, the site was added to the list of World Heritage in danger, a decision that reflected both the deterioration of the buildings and the insecurity that had made the region difficult to monitor.

Solar cookers are devices that use sunlight to heat food, and they exist in dozens of designs, from simple cardboard panels to large mirrors mounted on tracking frames. Their appeal is easy to see. Roughly a third of the world's population still burns wood, charcoal or animal dung to cook, often indoors and often in kitchens with no chimney, and the smoke from these fires is linked to serious respiratory illness. A cooker that needs no fuel at all therefore appears to answer several problems at once.

All solar cookers work on the same principle. Most designs belong to one of three broad families: box cookers, panel cookers and parabolic concentrators, which concentrate light with a curved mirror. Sunlight arriving at the Earth's surface carries energy at a rate of roughly one kilowatt per square metre at midday when the sky is clear. A cooker succeeds by doing three things with that energy: gathering it over an area larger than the food itself, converting it into heat in a dark surface, and preventing that heat from escaping. What differs between designs is the balance they strike between these three tasks, and the temperature they can reach as a result.

A box cooker is essentially a shallow insulated container with a transparent lid. The sides and base are packed with insulation — straw, sawdust, wool or foam — and the inner lining is painted black, because a dark surface absorbs far more of the light falling on it than a pale one does. A sheet of glass, or occasionally clear plastic, forms the lid. Many models add a reflector, a polished metal sheet hinged along the top edge and angled towards the sun, which bounces extra light into the box. Inside stands the pot, usually dark and fitted with its own close-fitting lid to stop moist air escaping. The whole arrangement is light enough to be carried by one person and simple enough to be repaired with local materials.

Sunlight passes through the glass and is absorbed by the black lining and by the pot. Because the pot is now warm, it gives off energy again, but at longer wavelengths, in the infrared, and ordinary glass transmits much less of this than it does visible light. The heat is therefore trapped. The glass has a second function: it stops the air inside the box from rising and drifting away, so that convection, which would otherwise carry heat out of the top, is largely suppressed. The insulation performs the third task, slowing the movement of heat by conduction through the base and the walls. In good conditions a well-built box cooker will reach temperatures of 120 °C or more, enough to boil water and to cook rice or lentils, though not enough to fry or brown food.

Panel cookers take a cheaper approach. A single sheet of card coated with reflective foil is folded into a shape that concentrates light on a pot placed in the middle, and the pot itself sits inside a transparent plastic bag or a glass bowl. The bag replaces the box: it holds a layer of still air around the pot and lets sunlight through. A panel cooker can be made for very little money and folds flat for transport, but it is fragile and usually slower than a box.

Parabolic cookers use a curved mirror to concentrate light on a single point. Because all the energy falling on the dish is delivered to a small area, temperatures rise far higher than in a box, and food can be fried or browned in a way that is impossible in a milder cooker. The disadvantage is that the dish must be turned to follow the sun every few minutes, and the concentrated beam is dangerous: cooks wear dark glasses to protect their eyes, and burns have been reported when the devices have been used carelessly.

The limitations of solar cooking are obvious enough. A cooker produces nothing at night, little in cloudy weather and less in winter, and its performance falls when wind cools the lid or when the sun is low in the sky. Measured efficiency also depends on altitude, on the quantity of food and even on how often the lid is lifted to check progress. This makes comparisons difficult, and there is still no single agreed method for testing cookers, so claims made by manufacturers and by aid projects should be treated with caution. Researchers also disagree about how much heat is lost through the lid and how much through the base.

One of the most valuable uses of a solar cooker is not cooking at all. Heating water to about 65 °C for a short period kills the bacteria and viruses that cause diarrhoea, and a cooker that cannot boil an egg can easily reach that temperature. A small indicator containing a wax that melts at a set point changes colour to show that the water is safe to drink. Yet solar cookers have spread more slowly than their apparent advantages would suggest. They demand that someone be at home at the right time of day, they do not suit every cuisine, and the taste and texture of food cooked slowly in a box are unfamiliar. Projects that have simply handed out cookers without asking what people actually cook have often ended with the devices unused in a cupboard.

Few areas of consumer law look quite as strange as the rules governing Sunday shopping. In England and Wales a large store may open for six hours on a Sunday, but a small one may open all day; in Scotland there is no comparable restriction; in Germany most shops close, with a handful of exceptions each year. The result is a patchwork that satisfies almost nobody. Retailers complain about lost trade, shop workers about lost weekends, and those who value a common day of rest about the erosion of something they believe a good society ought to protect. The question at the heart of the argument is simple: should shops be closed on Sundays at all?

Sunday closing has religious roots. Until the nineteenth century, laws in much of Europe and North America required the day to be kept free of ordinary work, and the restrictions that survived into the twentieth century were defended in roughly those terms. As leisure and disposable income grew, however, pressure to open increased. Several European countries have since relaxed their rules, usually after long public argument. In Britain the process was gradual: certain categories of goods were freed first, and the Sunday Trading Act of 1994 finally allowed large shops to open, but only for six hours and only between ten in the morning and six in the evening. Shops must still close on Easter Sunday. The Act was a compromise, and it has been criticised as such ever since.

Those who want the remaining limits removed make a straightforward economic case. Consumers, they argue, should be free to shop when it suits them; tourists expect shops to be open; and restrictions cost jobs. The evidence is less clear than this suggests. Studies of extended trading hours in several countries have found that most of the extra sales are not new spending but spending moved from another day or another shop. A longer week does not necessarily mean a bigger one. Where liberalisation has produced growth, it has tended to occur in areas that attract many visitors, where the demand is genuinely additional.

The costs, by contrast, are easy to identify. Sunday staff must be paid more, and the same overheads — lighting, heating, security — are spread over fewer customers. Some retail analysts argue that the extra hours are profitable mainly for large chains that can absorb the expense, while small shops lose the one advantage they had, which was being open when the giants were shut. The settlement of 1994 was, in this sense, a protection for smaller traders as much as a restriction on larger ones.

The argument that matters most, however, concerns the people who work in shops. Surveys of retail employees consistently find that a substantial minority would prefer not to work on Sundays, and that those who do often value the extra pay rather than the hours themselves. British shop workers have some legal protection: many of them can refuse Sunday work, though exercising that right may affect their chances of promotion. A common day off is not a luxury for people who spend the rest of the week serving the public.

Beyond the workplace lies a broader claim: that a shared day of rest has a value which cannot be measured in sales. Sunday is when families with different working hours can eat together, when amateur sports clubs play and when volunteers run events. Remove the day and something quietly disappears. The objection to this is that the shared day is already largely fictional. Hospitals, restaurants, transport and call centres operate seven days a week, and millions of people work at weekends as a matter of course. It is hard to argue that a society needs a common day of rest while treating so many of its essential workers as exceptions.

Then there is the question of consistency. The current law turns on the size of a shop, which is an odd basis for a moral rule: it is difficult to explain why a family running a large supermarket should be treated differently from a family running a small one. And the high street is no longer the only market. Anyone who wants to buy something on a Sunday evening can do so from a phone, and a law that closes a shop but leaves an online warehouse working does not protect anybody's rest; it merely redirects the spending. A shopper who finds a store closed on Sunday morning can order the same item online within minutes.

My own view is that the restrictions should be kept, but for different reasons and in a different form. The strongest argument for Sunday closing was never really about shopkeepers; it is that a society benefits when most of its members rest at the same time. That principle, however, cannot be defended by a rule that applies only to shops above a certain size, and it will not survive while so many workers are excluded from it. I would prefer a law that gives every employee the right to refuse Sunday work without penalty, pays those who do work a premium, and leaves opening hours to local decision. That would be a genuine protection of rest rather than a gesture towards it.