The culprit is a molecule called gliadin, which is found in certain gluten-containing grains and causes symptoms in gluten-sensitive people. The grains that cause the greatest problems are wheat, rye, barley, spelt, and kamut; whereas corn, rice, millet, and buckwheat are generally considered safe.
The Forth Bridge's piers are constructed from 120,000 cubic yards of concrete and masonry, faced with 2 ft thick granite. 200 trains use the bridge every day, carrying 3 million passengers each year. The total painted area of the Forth Bridge is 230,000 sq metres, requiring 240,000 litres of paint.
Bridges and tunnels The Clifton Bridge. In 1831 Brunel was chosen to build the Clifton Bridge over the River Avon at Bristol. It was a suspension bridge, and very high so ships could sail under it. At first, workers crossed the river in a basket! The basket ran along beneath an iron bar 307m (1000 feet) long.