Iron pillar of Delhi
The iron pillar of Delhi, the capital city of India, is one of the world's foremost metallurgical curiosities, standing in the famous Qutb complex. The pillar—almost seven metres high and weighing more than six tonnes—was erected by Chandragupta II Vikramaditya[1]. It is the only piece of the Hindu temple remaining, which stood there before being destroyed by Qutb-ud-din Aybak to build the Qutub Minar and Quwwat-ul-Islam mosque. Qutub built around it when he constructed the mosque.
The pillar is made up of 98% wrought iron of pure quality, and is a testament to the high level of skill achieved by ancient Indian iron smiths in the extraction and processing of iron. It has attracted the attention of archaeologists and metallurgists as it has withstood corrosion for the last 1600 years, despite harsh weather.
Description
The pillar, almost seven metres high and weighing more than six tonnes, was erected by Chandragupta II Vikramaditya (375 AD-414 AD), (interpretation based on careful analysis of archer type Gupta gold coins) of the Gupta dynasty that ruled northern India 320-540. The pillar with the idol of Garuda at the top was originally located at a place called Vishnupadagiri (meaning “Vishnu-footprint-hill”). This place has been identified as modern Udayagiri, situated in the close vicinity of Besnagar, Vidisha and Sanchi. These towns are located about 50 kilometres east of Bhopal, in central India. There are several aspects to the original erection site of the pillar at Udayagiri. It must be worth noting that Vishnupadagiri is located on the Tropic of Cancer and, therefore, was a centre of astronomical studies during the Gupta period. The Iron Pillar served an important astronomical function, when it was originally at Vishnupadagiri. The early morning shadow of the Iron Pillar fell in the direction of the foot of Anantasayain Vishnu (in one of the panels at Udayagiri) only in the time around summer solstice (June 21). The creation and development of the Udayagiri site appears to have been clearly guided by a highly developed astronomical knowledge. Therefore, the Udayagiri site, in general, and the Iron Pillar location in particular, provide firm evidence for the astronomical knowledge that existed in ancient India around 400 AD.
The pillar bears an inscription which states that it was erected as a flagstaff in honour of the Hindu god, Vishnu, and in the memory of the Gupta King Chandragupta II (375-413). Made up of 98% wrought iron of pure quality, it is 23 feet 8 inches (7.21 m) high and has a diameter of 16 inches (0.41 m). Also, it was confirmed that the tempratures required to form such kind of pillars cannot be achieved by combustion of coal. The pillar is a testament to the high level of skill achieved by ancient Indian iron smiths in the extraction and processing of iron.
A fence was erected around the pillar due to the popularity of a tradition that it was considered good luck if you could stand with your back to the pillar and make your hands meet behind it.
Scientific analysis
- See also: Wootz steel
Metallurgists at Kanpur IIT have claimed that a thin layer of "misawite", a compound of iron, oxygen, and hydrogen, has protected the cast iron pillar from rust. According to them, the protective film took form within three years after erection of the pillar and has been growing ever so slowly since then. After 1,600 years, the film has grown just one-twentieth of a millimetre thick, according to R. Balasubramaniam of the IIT. In a report published in the journal Current Science, Balasubramaniam suggests that the protective film was formed catalytically by the presence of high amounts of phosphorus in the iron — this phosphorus is as much as one per cent against less than 0.05 per cent in today's iron. The high phosphorus content would be a result of the iron-making process practiced by ancient Indians, who reduced iron ore into steel in one step by mixing it with charcoal. Modern blast furnaces, on the other hand, use limestone in place of charcoal, yielding molten slag and pig iron that is later converted into steel. In the modern process most phosphorus is carried away by the slag. Balasubramaniam's theories remain disputed.
Stating that the pillar is "a living testimony to the skill of metallurgists of ancient India", Balasubramaniam said the "kinetic scheme" that his group developed for predicting growth of the protective film may be useful for modeling long-term corrosion behaviour of containers for nuclear storage applications.
Another theory suggests that the reason that the pillar resists rust is due to its thickness, which allows the sun to heat the pillar sufficiently during the day to evaporate all rain or dew from its surface. The accumulated heat also keeps the surface dry at night.[citation needed]
It was claimed in the 1920s that iron manufactured in Mirjati near Jamshedpur is similar to the iron of the Delhi pillar.[2]
See also
Notes
Further reading
- The Early use of Iron In India. Dilip K. Chakrabarti.1992. New Delhi: The Oxford University Press.
- Delhi Iron Pillar: New Insights R. Balasubramaniam, 2002. Shimla: Indian Institute of Advanced Studies and Delhi: Aryan Books International. (Hardbound, ISBN-81-7305-223-9)[1] [2]
- Story of the Delhi Iron Pillar, R. Balasubramaniam, 2005, New Delhi: Foundation Books. (Paperback, ISBN-81-7596-278-X).
- Review in Current Science
- The Delhi Iron Pillar : Its Art, Metallurgy and Inscriptions/edited by M.C. Joshi, S.K. Gupta & Shankar Goyal. 1996
External links
- List of Publications on Delhi Iron Pillar by R Balasubramaniam
- The Delhi Iron Pillar
- Corrosion resistance of Delhi iron pillar
- Nondestructive evaluation of the Delhi iron pillar Current Science, Indian Academy of Sciences, Vol. 88, No. 12, 25 June 2005 (PDF)