Ikigai Daily
Menu
WonderAncient metallurgy fact

Wootz was a steel made in southern India and Sri Lanka by melting iron with carbon in small sealed clay pots. Traded west as ingots, it was prized because careful forging brought out flowing, watery bands in the blade, the pattern of famed Damascus swords.

South Asia, from the mid-1st millennium BCE

EngineeringTradeArchaeologyTechnology

The story behind the card

Crucible steel of this kind was made in southern India from around the middle of the first millennium BCE. Because the metal melted fully in a sealed pot, it took up carbon evenly, giving a hard, high-carbon steel. In Sri Lanka, the archaeologist Gill Juleff found ancient furnaces built on hillsides to catch the monsoon winds, which blew air through them instead of bellows. Ingots travelled to Persia and Syria, where smiths forged them into the blades Europeans called Damascus steel. The wavy bands are sheets of tiny carbides, hard compounds of iron and carbon. In the 1990s J. D. Verhoeven and Alfred Pendray showed that traces of vanadium in the ore, together with repeated heating during forging, are needed for the pattern to form.

Türkçe oku
Wootz, Güney Hindistan'da ve Sri Lanka'da demirin karbonla birlikte küçük, kapalı kil potalarda eritilmesiyle yapılan bir çelikti. Külçe hâlinde batıya satılır, ustalıkla dövüldüğünde bıçakta beliren dalgalı desenleriyle değer görürdü; ünlü Şam kılıçlarının deseni buydu.
Güney Asya, MÖ 1. binyılın ortasından itibaren

Bu tür pota çeliği, MÖ 1. binyılın ortalarından itibaren Güney Hindistan'da üretiliyordu. Metal kapalı bir potada tamamen eridiği için karbonu eşit biçimde alır, sert ve yüksek karbonlu bir çelik ortaya çıkardı. Arkeolog Gill Juleff, Sri Lanka'da muson rüzgârını yakalamak için yamaçlara kurulmuş eski fırınlar buldu; bu fırınlarda körüğün işini rüzgâr görüyordu. Külçeler İran'a ve Suriye'ye gider, oradaki demirciler onları Avrupalıların “Şam çeliği” dediği kılıçlara dönüştürürdü. Dalgalı desenler, demir ile karbonun oluşturduğu sert bileşikler olan karbürlerin mikroskobik tabakalarıdır. 1990'larda J. D. Verhoeven ve Alfred Pendray, desenin oluşması için cevherdeki eser miktarda vanadyumun ve dövme sırasında tekrar tekrar ısıtmanın gerektiğini gösterdi.

Sources and further reading

Background reading: Wootz steel
Get the mobile appAbout our cards

Related cards

These cards share a subject or reading mode with the card above.

WonderTrade

Shipping containers, steel boxes built to standard sizes, let cargo move from ship to lorry to train without being unpacked. Since the first container voyage in 1956, they have cut loading costs so sharply that they helped create today's global trade.

Before containers, dockworkers loaded ships one sack, crate and barrel at a time, and loading a ship could take days or weeks. The American trucking entrepreneur Malcolm McLean changed that. On 26 April 1956 his converted tanker Ideal X sailed from Newark to Houston with 58 containers on deck. McLean calculated that loading cost about 16 cents a ton, against almost six dollars for cargo loaded piece by piece. International standards for container sizes and corner fittings followed in 1968–1970, so any box could fit any crane, ship or lorry. Ports changed, many dockworkers lost their jobs, and making goods far from where they are sold became cheap.

ContainerizationRead card
WonderArchitecture

Angkor, capital of the Khmer Empire in today's Cambodia from the ninth to the fifteenth century, was ringed by giant reservoirs, moats and canals that stored monsoon rain and moved water across an urban area of about 1,000 square kilometres.

The largest reservoirs, called barays, are vast rectangles banked with earth: the West Baray, built in the eleventh century, measures about eight kilometres by two and still holds water. Moats such as the one around Angkor Wat framed temples modelled on the sacred mountain and surrounding oceans of Hindu and Buddhist cosmology. Radar and aerial surveys published in 2007, and airborne laser scanning (lidar) that saw through the forest in 2012, revealed roads, canals and house mounds across at least 1,000 square kilometres, the largest known pre-industrial settlement. Researchers still debate how much the barays watered rice fields. Tree rings show long droughts broken by intense monsoons in the fourteenth and fifteenth centuries, which damaged the network and probably contributed to Angkor's decline.

Angkor hydraulic systemRead card
WonderArchaeology

The Dover Bronze Age Boat, found under a road in Dover in 1992, was built about 3,500 years ago from oak planks sewn together with yew and made watertight with moss and animal fat.

Workers building the A20 road between Folkestone and Dover uncovered the boat on 28 September 1992, six metres below the surface. Waterlogged, airless ground had kept the oak from rotting. Archaeologists worked for nearly a month to lift a 9.5-metre section; the rest ran under nearby buildings and had to be left in place. The planks are held together by twisted yew stems and by wooden wedges driven through cleats, raised blocks carved out of the planks themselves. It is dated to about 1575 to 1520 BCE, which makes it one of the oldest seagoing boats known. Whether it ever crossed the Channel is still debated. It is on display in Dover Museum.

Dover Bronze Age BoatRead card
WonderEngineering

The Plimsoll line, a circle with a line through it painted on a ship's hull, marks how deep a loaded ship may safely sit in the water. Extra lines beside it allow for fresh water, tropical water and winter seas, where the safe limit is different.

The mark is named after Samuel Plimsoll, a British member of parliament who campaigned in the 1870s against “coffin ships”: vessels sent to sea overloaded and often over-insured, so that owners could profit even if the ship sank and its crew drowned. His 1873 book Our Seamen stirred public anger, and the Merchant Shipping Act of 1876 made the load-line mark compulsory on British ships. International conventions in 1930 and 1966 extended load lines to ships worldwide. The letters beside the mark stand for tropical fresh water (TF), fresh water (F), tropical (T), summer (S), winter (W) and winter North Atlantic (WNA). Canvas plimsoll shoes are said to take their name from the band where the upper meets the sole, which recalls the line.

Plimsoll lineRead card
WonderEngineering

A qanat is an underground channel, developed in ancient Persia, that brings groundwater from the foot of hills to fields and towns using gravity alone. From above, a qanat shows as a line of shaft openings across dry land.

Builders start with a 'mother well' dug down to the water table, then cut a tunnel back towards the surface on a very gentle slope, so the water flows without wearing away the channel. Vertical shafts along the route let workers lift out soil, bring in air and later clean the tunnel. The Qasabeh qanat at Gonabad in eastern Iran, dated to between 700 and 500 BCE, has a mother well more than 360 metres deep and about 33 kilometres of channels, and still carries water. In 2016 UNESCO listed eleven Iranian qanats together as a World Heritage site, recognising both the engineering and the old customs for sharing the water fairly.

Qanat water systemsRead card
Next card in the archiveA Fresnel lens replaces the thick curved glass of an ordinary lens with thin concentric rings, each shaped to bend light at the right angle. Invented for lighthouses in the 1820s, it focuses light just as strongly with far less glass and weight.Read next →