Iron

Iron figurine from 10 North Street, Cromford, Derbyshire

There are three main types of iron that should be considered: wrought, cast and steel. Wrought Iron has a melting point of 1535 degrees C so it comes out of the furnace solid and is worked solid. It is hammered into shape and forms a tough finished product. It is good for tools and swords. It has less than 0.3 per cent carbon content. Cast Iron comes out of the furnace molten and is poured into moulds to make its shape. It is brittle so it does not produce good tools or edged weapons. Often it is used for decorative objects. It has more than 2 per cent carbon. These two forms are dependent on the type of ore available, high-carbon ores will not make good wrought iron. Chinese ores, for example, are useful only for cast iron, which is why there is so much decorative Chinese ironwork. Steel is a combination of iron and the right amount of carbon – between 0.3 and 2 percent – which makes it particularly tough and flexible. It is capable of holding an edge and is therefore very useful for tools and weapons. It is, however, very difficult to manufacture and involves “cooking” the iron and carbon together for many hours at more than 1100 degrees C.

The “Three Age” history of the introduction of iron in Europe is unique and not reflected anywhere else in the world. In southern Africa, for example, there never was a Bronze Age and the first metal to be used was iron. In North America native copper was hammered into shapes but was never smelted. In Europe the Iron Age followed the Bronze Age but there was no distinct line between the two. Iron was merely an additional metal. It is difficult to form into complex shapes, unlike bronze, and it corrodes easily so it was not a suitable material for all uses. By the 2nd millennium BCE a few iron items were in circulation, such as pins and awls but around 1100 BCE the metal took off in a big way. It appeared throughout the near east, Europe and Britain almost simultaneously.

There are two sources of iron – meteoric iron that is extremely rare and can be identified by its high nickel content, and iron ores. It appears as oxides and sulphides; both are commonly available. Iron ore is rarely pure so there are almost always other constituents in any iron item. Unfortunately it is impossible to assign chemical “signatures” to European ores because they vary so much, so the inclusions are not useful for sourcing raw materials used in archaeological artefacts.

Thanks to Prof Elizabeth Slater, head of department at the University of Liverpool school of archaeology for clear lectures on artefacts and materials. J M Cronyn’s Elements of Archaeological Conservation has also been consulted.

Eugenius Birch (1818-84)

Engineer Eugenius Birch is most famous for his seaside pier constructions. During his life he was responsible for no fewer than 14 of them including some of the best known such as Brighton West and Blackpool North. Born in Gloucester Terrace, Shoreditch, Eugenius was the son of a corn dealer, John Birch and his wife Susanne. His older brother, John Brannis Birch, worked closely with Eugenius on his engineering projects.

Pier end
Aberystwyth Pier – Mid Wales. The original pier was designed by Eugenius Birch and built in 1865. In this photo only a very small part of Birch’s original work can be seen. A long section at the seaward end was washed away in a storm less than a year after the pier opened and it was replaced with a narrower part, several years later, by a different engineer. Only the section under the pavilion (the yellow building) is Birch’s work

Birch’s early education took place in Brighton but he developed his taste for engineering while watching the cutting of the Regent’s Canal near his home in London. While he was a young boy he submitted an idea to the Greenwich Railway Company that, at the time, was novel and innovative. He suggested a method to put wheels under a railway carriage, rather than at the sides.

At the age of 16 he was apprenticed to a works in Limehouse, London. Within three years he was achieving success with medals for his drawings of working engines and machinery.As well as piers Birch was responsible for other, more conventional, structures such as bridges and he was involved in building the Calcutta to Delhi railway in India where he learned some of the oriental design that he later incorporated into his seaside structures. His first pier was built at Margate in 1853 but altogether he was responsible for 14 around England and Wales: Aberystwyth, Blackpool North, Bournemouth, Brighton West, Deal, Eastbourne, Hastings, Hornsea, Lytham, Margate, New Brighton, Plymouth, Scarborough and Weston-Super-Mare Birnbeck.

Most were constructed in cast iron because he believed that wrought iron piers would be a hazard if they were hit by boats. He argued that wrought iron would bend and buckle, and would take a great deal of repairing. Cast iron, however, would shatter, reducing the damage area and hence cutting repair costs. Neglect and old age have put paid to most of Birch’s piers, however, and little now remains of his original work.