He swept his arm over the pine, glass and steel that curved above our heads.
Fortunately for traditionalists, if not for safety or access considerations, the curved shape of many tube station platforms, as well as the variety of trains in operation, means similar devices might not necessarily work, leaving the Underground's gap unfilled.
The oak staves from which barrels are made were originally softened over a small fire in order to bend them into the requisite curved shape.
The more you inflate a balloon, to give a two-dimensional example, the less pronouncedly curved its surface gets.
Since there are an infinite number of ways of being curved and only one of being flat, this needs explaining.
So are curved screens, which are touted as making viewing more immersive (see picture).
At the front of their bulbous blue heads they have curved fangs that act as jaws.
Perched on ten-metre-high (33 feet) curved supporting pillars, rather like a grounded spaceship, it is set back from the road in a landscaped garden.
But Londoners universally refer to the newest addition to their skyline as "the Gherkin", thanks to the 41-storey building's distinctive, curved profile, which actually looks more like a pine cone (see right).
At some scales space is not at all flat: the power of Albert Einstein's theory of general relativity lies in its interpretation of gravity in terms of curved space.
Space-time, as it is known, has four dimensions: the three familiar spatial ones of length, breadth and height, and time.Space-time can be distorted or curved by the presence of massive objects, such as stars.
