Inventions in iron and transport

1Why this matters

Machines and engines need metal, and factories need a way to bring in raw materials and send out finished goods. The Industrial Revolution therefore depended on two further revolutions: cheaper, better iron, and faster, cheaper transport. Railways in particular changed how people everywhere, including in colonial Africa, experienced distance.

2Iron and steel

• Abraham Darby (1709) smelted iron using coke (coal baked to remove impurities) instead of charcoal at Coalbrookdale. Britain's forests were shrinking, so this freed iron-making from wood. In 1779 his grandson's works erected the famous Iron Bridge across the River Severn.
• Henry Cort (1783–1784) developed rolling and the puddling process, which turned brittle cast iron into strong wrought iron cheaply and in large amounts.
• James Neilson (1828) introduced the hot blast, blowing heated air into furnaces and saving a great deal of fuel.
• Henry Bessemer (1856) invented a converter that made steel cheaply. Steel is stronger than iron and later replaced it for rails, ships and bridges.

3Roads and canals

• Turnpike trusts charged tolls to maintain roads. Engineers such as Thomas Telford and John McAdam built firm, well-drained roads; McAdam's layered stone surface is where the word "tarmac" comes from.
• Canals: the Bridgewater Canal (1761) carried coal to Manchester, and within a year the price of coal there fell by half. A "canal mania" followed, and by the 1820s Britain had a national canal network.

4Railways and steamships

Worked example: explaining an effect with numbers

Question: Explain why canals helped industry grow.

A horse pulling a barge on still water can move many times the load it could pull in a cart on a rough road. So canals made heavy goods such as coal, iron and pottery much cheaper to transport. The Bridgewater Canal is the evidence: within a year of its opening in 1761, the price of coal in Manchester had fallen by half. Cheaper coal meant cheaper steam power and cheaper goods, which helped factories expand.

Notice the pattern: mechanism (why it worked), then evidence (a date or figure), then consequence (what it led to).

Practice

Solution. Charcoal came from wood, and Britain's forests were running out. Coke came from coal, which Britain had in abundance, so iron could be produced in much larger quantities and more cheaply.

Solution. Any two of: moved raw materials and finished goods quickly and cheaply; created huge demand for iron, coal and engineering; carried workers and passengers; linked factories to ports; opened new markets.

Solution. Cast iron is hard but brittle; steel is both strong and flexible. Before 1856 steel was expensive. Bessemer's converter made it cheaply, so steel could be used for rails, ships, bridges and machines.

Solution. Trevithick's locomotive (1804), Stockton and Darlington (1825), Rainhill Trials (1829), Liverpool and Manchester (1830).