Iron pillar

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Iron pillar in the courtyard of the Quwwat-ul-Islam Mosque in the Qutb complex , Delhi (India)

The Iron Pillar in Delhi ( India ) is one of the oldest preserved metal monuments in the world. It has been in the courtyard of the Quwwat-ul-Islam mosque in the Qutb complex in the south of the city for about 700 to 1000 years ; However, its history goes back even further: it is sometimes referred to as the Ashoka column, but a Sanskrit inscription with the name Chandra and the mention of the Hindu god Vishnu places it in the time of the Gupta ruler Chandragupta II.

description

The iron pillar is 7.21 m high (1.12 m of it in the ground), weighs 6.5 t and has a diameter of 42 cm at its lower end, which decreases towards the top to about 30 cm. At its top there is a slender, multi-articulated and over 1.75 m high capital , which may have been crowned by a wheel ( chakra ), an attribute of Vishnu, or a standing or kneeling Garuda figure, which at the latest in Islamic times was melted down.

Manufacturing

The iron pillar is made of wrought iron and shows the extensive expertise that the early Indian iron smiths acquired in iron mining and processing. Due to its high weather resistance and lack of corrosion in the past 1600 years, it has aroused the interest of archaeologists and metallurgists (see below). The iron pillar was probably not cast, but made using the method of fire welding . The required temperatures of around 1200 ° C can be achieved by burning charcoal with a constant supply of oxygen.

Chandraguptas II inscription.
Sanskrit text and English translation
The pillar, 1976

history

The Iron Pillar was probably commissioned by the Gupta ruler Chandragupta II (r. 375-414), who was nicknamed "World Conqueror" ( Vikramaditya ) and was considered a great admirer of the Hindu god Vishnu, in the heyday of the Gupta Dynasty established - this interpretation is based on the inscription and on analyzes of old gold coins from the Gupta Empire.

The column with the chakra idol on its top was originally placed in a place called Vishnupadagiri ("hill with the footprint of Vishnu"). This place has been equated with the cave temples of Udayagiri near Sanchi and Vidisha . An inscription added (later?) To the column says that it was built in honor of the Hindu god Vishnu. The heroism and goodness of a king known as Chandra , who is identified by recent archaeological research as Chandragupta II, are also praised.

The place Vishnupadagiri is located on the northern tropic and was therefore possibly an astronomical observation center in the Gupta era. At the original location of the iron pillar in Vishnupadagiri , the pillar shadow fell in the direction of the foot of Anantasayain Vishnu once a year in the early morning on the summer solstice (June 21) . The establishment and development of Udayagiri was obviously accompanied by highly developed astronomical knowledge, which is why Udayagiri and in particular the Iron Pillar are solid evidence of the astronomical knowledge in ancient India around 400 AD.

If the original location of Udayagiri is correct, the column must have been taken as a trophy in the former Hindu temple in the area of ​​the 8th century in the Middle Ages (probably under Qutb-ud-Din Aibak or his son-in-law and successor Iltutmish in the early 13th century ) Tomara Rajputs founded and in the 12th century extended by the Chauhans fortress "Lal Kot". The temple and fortress were destroyed by Qutb-ud-Din Aibak at the end of the 12th century in order to build the Qutb Minar mosque tower and the Quwwat-ul-Islam mosque on this site. The iron pillar was placed in their inner courtyard.

Metallurgical investigations

Metallurgists from the IIT Kanpur came to the conclusion that a thin layer of “misawite” - a special lattice structure of an iron hydroxide - protected the iron column from corrosion. In their opinion, the protective layer spread within three years of the column's construction and has continued to grow slowly ever since. This information was mistakenly circulated by the media based on an article in Current Science . This article mentions that the protective film (according to R. Balasubramaniam of IIT Kanpur) only became 1/20 mm thick in the 1600 years. In another report of Current Science Balasubramaniam assumes that the protective film by the presence of a high phosphorus content was catalyzed in the iron - the phosphorus content in the iron of the column is about 0.1 percent as opposed to 0.05 percent in the present iron.

There are three known methods that explain the protective layer, two of which are explained below:

According to one explanation, the high phosphorus content could result from the way the early Indians made iron - namely, by using charcoal as a reductant to reduce iron ore to low-carbon iron at a stable rate . Modern blast furnaces used coke instead of charcoal and also limestone in order to later be able to produce steel with the pig iron . In the modern process, most of the phosphorus is removed with the slag produced by the limestone . Since lime was not used in ancient blast furnaces, a higher amount of phosphorus remained in the material.

Another possibility is that the column could resist the rust due to its layer thickness, which allows the sun to heat the column during the day so that all the rain or dew evaporates from its surface. The accumulated heat could keep the surface dry in this way even at night.

For a detailed account of all possible theories about the column's resistance to corrosion in Delhi, the article by Balasubramaniam in Corrosion Science can be used as a source.

In the 1920s it was claimed that the iron made in Mirjati near Jamshedpur was similar to the iron found in the Iron Pillar. Further research of the national metallurgical laboratory at the (tribal associated) Advasi -iron not confirmed this claim.

Others

In popular belief, it is said that whoever stands with his back to the Iron Pillar, clasps it backwards with his hands and whose fingertips touch each other should be particularly lucky. After various damage and graffiti, a fence was built around the originally free-standing iron column in 1997.

literature

  • TR Ananthartaman: The Iron Pillar at Delhi. In: S. Ranganathan (Ed.): Iron and Steel Heritage of India. ATM, 1997, pp. 1-28
  • King Chandra and the Mehrauli Pillar . MC Joshi, SK Gupta and Shankar Goyal, Eds., Kusumanjali Publications, Meerut, 1989.
  • The Rustless Wonder - A Study of the Iron Pillar at Delhi . TR Anantharaman, Vigyan Prakashan, New Delhi, 1996.
  • Delhi Iron Pillar: New Insights . R. Balasubramaniam, Delhi: Aryan Books International and Shimla: Indian Institute of Advanced Studies, 2002, Hardbound, ISBN 81-7305-223-9 . [1] [2]
  • The Delhi Iron Pillar: Its Art, Metallurgy and Inscriptions . MC Joshi, SK Gupta and Shankar Goyal, Eds., Kusumanjali Publications, Meerut, 1996.
  • The World Heritage Complex of the Qutub. R Balasubramaniam, Aryan Books International, New Delhi, 2005, Hardbound, ISBN 81-7305-293-X .
  • Story of the Delhi Iron Pillar . R Balasubramaniam, Foundation Books, New Delhi, 2005, Paperback, ISBN 81-7596-278-X .
  • Delhi Iron Pillar . (in two parts), R. Balasubramaniam, IIM Metal News Volume 7, No. 2, April 2004, pp. 11-17. and IIM Metal News Volume 7, No. 3, June 2004, pp. 5-13. ( PDF )
  • New Insights on the 1600-Year Old Corrosion Resistant Delhi Iron Pillar . R. Balasubramaniam, Indian Journal of History of Science, 36 (2001) 1-49. ( PDF )
  • The Early use of Iron In India. Dilip K. Chakrabarti. 1992. New Delhi: The Oxford University Press.
  • Non-destructive testing method of the iron pillar from Delhi Current Science , Indian Academy of Sciences, Issue 88, No. 12, June 25, 2005. (PDF; 190 kB)

Web links

Commons : Iron Pillar  - collection of images, videos and audio files

Individual evidence

  1. ↑ Identity of Chandra and Vishnupadagiri of the Delhi Iron Pillar Inscription: Numismatic, Archaeological and Literary Evidence, R Balasubramaniam, Bulletin of Metals Museum, 32 (2000) pp. 42-64.
  2. ↑ On the Astronomical Significance of the Delhi Iron Pillar, R Balasubramaniam and Meera I Dass, Current Science, volume 86 (2004) pp. 1134–1142. ( PDF )
  3. ↑ Mystery of Delhi's Iron Pillar unraveled, Press Trust of India, Posted online: Thursday, July 18, 2002 at 1500 hours IST.
  4. ↑ On the Growth Kinetics of the Protective Passive Film of the Delhi Iron Pillar, R Balasubramaniam, Current Science, Volume 82 (2002) pp. 1357-1365. ( PDF ( Memento of the original from December 30, 2006 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. ) @1@ 2Template: Webachiv / IABot / tejas.serc.iisc.ernet.in
  5. ↑ B. Sanyal and R. Preston, Note on Delhi Pillar, Chemical Research Laboratory, London 1952.
  6. ↑ On the Corrosion Resistance of the Delhi Iron Pillar, R. Balasubramaniam, Corrosion Science, Volume 42 (2000) pp. 2103-2129. ( PDF )
  7. ↑ Andrew McWilliam 1920, cited in Chakrabarti 1992.
  8. ^ AK Lahiri, T. Banerjee and BR Nijhawan, “Some Observations on Corrosion-Resistance of Ancient Delhi Iron Pillar and Present-time Adivasi Iron Made by Primitive Methods,” NML Tech. J., 5 (1963) 46-5.

Coordinates: 28 ° 31 '28.76 "  N , 77 ° 11' 6.25"  E