means of charcoal, which became gradually more expensive as agriculture
improved and forests were cut away. The beginning of the use of coke in
iron smelting had been made in the last century, and in 1780 a new method
was invented of converting into available wrought-iron coke-smelted iron,
which up to that time had been convertible into cast-iron only. This
process, known as "puddling," consists in withdrawing the carbon which
had mixed with the iron during the process of smelting, and opened a
wholly new field for the production of English iron. Smelting furnaces
were built fifty times larger than before, the process of smelting was
simplified by the introduction of hot blasts, and iron could thus be
produced so cheaply that a multitude of objects which had before been
made of stone or wood were now made of iron.

In 1788, Thomas Paine, the famous democrat, built in Yorkshire the first
iron bridge, which was followed by a great number of others, so that now
nearly all bridges, especially for railroad traffic, are built of cast-
iron, while in London itself a bridge across the Thames, the Southwark
bridge, has been built of this material. Iron pillars, supports for
machinery, etc., are universally used, and since the introduction of gas-
lighting and railroads, new outlets for English iron products are opened.
Nails and screws gradually came to be made by machinery. Huntsman, a
Sheffielder, discovered in 1790 a method for casting steel, by which much
labour was saved, and the production of wholly new cheap goods rendered
practicable; and through the greater purity of the material placed at its
disposal, and the more perfect tools, new machinery and minute division
of labour, the metal trade of England now first attained importance. The
population of Birmingham grew from 73,000 in 1801 to 200,000 in 1844;
that of Sheffield from 46,000 in 1801 to 110,000 in 1844, and the
consumption of coal in the latter city alone reached in 1836, 515,000
tons. In 1805 there were exported 4,300 tons of iron products and 4,600