Scotsmen seem to have an affinity for rubber. It was, of course, as you may recall from yesterday, the Englishman, Joseph Priestly, later the discoverer of oxygen, who found a name for this bouncy substance when he noted around 1770 that it was very effective for "wiping from paper the marks of a black-lead pencil". But the Scots seem to have taken it over after that. In the 1820s, as we have seen, Charles Mackintosh devised a way of using it for raincoats. Then in 1845, another Scot called William Thompson put it on a wheel. Cart wheels up till then were always rimmed with metal, but Thompson had the bright idea of fitting them with "tyres" of rubber. They had the advantage of being less noisy than the metal ones, and the ride was slightly easier, particularly on the cobbled city streets that were the norm. But it was Scotsman number three who made the breakthrough. One of the most striking qualities of air is its compressibility. A given amount of it can be squeezed into a smaller and smaller volume when sufficient pressure is applied and, like rubber, it is capable of expanding and contracting in response to external forces. The notion was first articulated by Irishman Robert Boyle, in 1660, when he wrote: "There is a spring, or an elastic power, in the air in which we live." He went on to quantify this bounciness in Boyle's Law, which has become one of the basic formulae used today in computerised weather forecasts.
But Scotsman John Dunlop found for this elastic quality of air a use that some would see as even more important. John Boyd Dunlop was born in Ayrshire in 1840, qualified as a veterinary surgeon, and shortly afterwards moved to Ireland to build up an extensive veterinary practice in Gloucester Street, in Belfast. Many of his patients were horses, and they, of course, had carriages - and hence the story goes that Dunlop developed an interest in the wheel, and possible improvements to its design that might lead to greater comfort and efficiency.
Dunlop concentrated first on his son's bicycle. In 1888 he made a tube out of sheet rubber, fixed it to a wooden disc and filled it with compressed air using a football pump. This novel wheel was so spectacularly successful in terms of potential speed and comfort, that he patented the device immediately. When a cyclist using inflatable tyres won the cycle race at the Queen's College sports in May 1889, the viability of the invention was assured, and Dunlop in due course became a household name.