Academic Reading — Test 171

Reading passage

For much of the early nineteenth century, natural rubber was regarded as a curiosity of limited practical worth. Harvested as a milky fluid from certain tropical trees and then dried, it possessed a remarkable elasticity that fascinated inventors and manufacturers alike. Yet the raw material had a crippling defect: it could not cope with changes in temperature. In the heat of summer it grew soft, sticky and foul-smelling, while in winter it hardened, cracked and lost all its springiness. Waterproof coats, boots and other goods made from it tended to fail within a single season, and many of the businesses that had rushed to exploit the substance collapsed when customers returned their ruined purchases. The promise of rubber was obvious; the means of taming it was not. The breakthrough came through the dogged persistence of an American named Charles Goodyear, who devoted years and a considerable fortune to the problem despite having no formal training in chemistry. Goodyear experimented endlessly, mixing rubber with every powder and compound he could obtain. According to the widely repeated account, the decisive discovery occurred in 1839 when he accidentally dropped a mixture of rubber and sulphur onto a hot stove. Instead of melting into a useless paste, the material charred slightly at the edges but remained firm and elastic. He had stumbled upon the principle of a process later named vulcanisation, after Vulcan, the Roman god of fire. By heating rubber together with sulphur, Goodyear had created a substance that stayed flexible and stable across a wide range of temperatures. Even so, recognition and reward largely eluded him, and he died in debt, his patents tangled in costly disputes. Vulcanisation transformed rubber from a seasonal novelty into a dependable industrial material, and within a few decades it was being used for an enormous variety of products. One application, however, would prove especially significant for the age of personal transport. In the 1880s the bicycle had become immensely popular, but the machines of the day were uncomfortable to ride. Their wheels were fitted either with bare metal rims or with strips of solid rubber, and on the rough, cobbled roads of the period every bump was transmitted directly to the rider. These bone-shaking journeys discouraged many people from cycling at all, and inventors searched for a way to cushion the ride. The man usually credited with the modern solution was John Boyd Dunlop, a Scottish-born veterinary surgeon who had settled in Belfast. In 1887, watching his young son struggle to ride a tricycle over uneven ground, Dunlop conceived the idea of replacing the solid rubber with a hollow tube of fabric and rubber that could be filled with air. He fashioned an inflatable tube, wrapped it in tough canvas, and fitted it to the wheels. The result was dramatic: the air-filled, or pneumatic, tyre absorbed shocks far more effectively and rolled with noticeably less effort. Dunlop was granted a patent in 1888 and began commercial production soon afterwards. It is worth noting that he was not, in fact, the first to think of the idea. Another Scotsman, Robert William Thomson, had patented an air-filled tyre as early as 1845, decades before Dunlop, but Thomson's invention had been forgotten because the manufacturing techniques and the demand needed to make it succeed simply did not yet exist. Dunlop's timing, by contrast, was excellent. The bicycle boom created an immediate market, and racing cyclists quickly demonstrated that pneumatic tyres were not merely more comfortable but considerably faster. As word spread, solid tyres were abandoned almost overnight. The company that bore Dunlop's name grew rapidly, although he himself sold most of his interest in it relatively early and did not become especially wealthy from the enterprise. The principle he had popularised, however, was about to find an even larger stage. When the motor car emerged at the turn of the century, the pneumatic tyre was ready and waiting; without an air-filled cushion between wheel and road, fast motoring on the surfaces of the time would have been almost unbearable. The story of rubber is therefore really a story of two linked inventions. Goodyear's vulcanisation supplied a material that was strong and reliable, while Dunlop's tyre supplied the form that turned that material into the foundation of modern road transport. Neither man grew rich in proportion to the importance of his work, and both are sometimes remembered chiefly through the tyre companies that later adopted their surnames. Yet the combined effect of their efforts is difficult to overstate. Every car, lorry, bus and bicycle that moves today rolls on the descendants of a sulphur-hardened gum and an air-filled tube, two modest innovations that quietly reshaped the way the world travels.