War, Sheffield changed hands several times, finally falling to the Parliamentarians, who demolished (slighted) the castle in 1648. The Industrial Revolution brought large-scale steel making to Sheffield in the 18th century. Much of the medieval town was gradually replaced by a mix of Georgian and Victorian buildings. Large areas of Sheffield's city centre have been rebuilt in recent years, but among the modern buildings, some old buildings have been retained. Industrial Sheffield Sheffield developed after the industrial revolution because of its geography. Fast-flowing rivers, such as the Sheaf, the Don and the Loxley, made it an ideal location for water-powered industries to develop. Raw materials, like coal, iron ore, ganister and millstone grit for grindstones, found in the nearby hills, were used in cutlery and blade production. As early as the 14th century, Sheffield was noted for the production of knives: By 1600 Sheffield was the main centre of cutlery production in England outside London, and in 1624 The Company of Cutlers in Hallamshire was formed to oversee the trade. Examples of water-powered blade and cutlery workshops from around this time can be seen at the Abbeydale Industrial Hamlet and Shepherd Wheel museums in Sheffield. Around a century later, Daniel Defoe in his book A tour thro' the whole island of Great Britain, wrote: In the 1740s Benjamin Huntsman, a clock maker in Handsworth, invented a form of the crucible steel process for making a better quality of steel than had previously been available. At around the same time Thomas Boulsover invented a technique for fusing a thin sheet of silver onto a copper ingot producing a form of silver plating that became known as Sheffield plate. Originally hand-rolled Old Sheffield Plate was used for making silver buttons. Then in 1751 Joseph Hancock, previously apprenticed to Boulsover's friend Thomas Mitchell, first used it to make kitchen and tableware. This prospered and in 1762–65 Hancock built the water-powered Old Park Silver Mills at the confluence of the Loxley and the Don, one of the earliest factories solely producing an industrial semi-manufacture. Eventually Old Sheffield Plate was supplanted by cheaper electroplate in the 1840s. In 1773 Sheffield was given a silver assay office. In the late 18th century, Britannia metal, a pewter-based alloy similar in appearance to silver, was invented in the town. Huntsman's process was only made obsolete in 1856 by Henry Bessemer's invention of the Bessemer converter, but production of