Minerals and Metals in Ancient India v1.c27.s2.t3: Forge-Welding and Dhar Pillar
Minerals and Metals in Ancient India v1.c27.s2.t3
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Forge-Welding and Dhar Pillar
v1.c27.s2.t3.1
The marvel of the Delhi iron pillar is twofold: one, its apparent rustlessness and the other, probably more striking, is that it could be fabricated at all 1600 years back! It shows what excellence Indian smiths had reached in the art of forge-welding. Tylecote (1984) suggested that the ‘pancake’ forging technique was used, but Prakash and Tripathi (1986: 576) wondered how the said technique, possible for forging short circular objects, could be feasible for an iron pillar of the size as in Delhi.
v1.c27.s2.t3.2
Judging from weldlines on its surface, the Delhi iron pillar seems to have been built up from a great many lumps, weighing 20-30 kg which have been successively forge-welded together, under firing with a charcoal blast. (Turner, 1893: Hadfield, 1912) The archaeological excavations at Ujjain have revealed the existence of typical forge furnaces although the precise technique of forge-welding in ancient India remains a mystery.
v1.c27.s2.t3.3
The surface of the Delhi iron pillar shows marks of hammer-blows. Heavy mechanical working at high temperature is also attested through (a) measured high density (Hadfield’s measurement 7.81; NML measurement 7.747), (b) low porosity, (c) nearly identical yield point (23.5) and maximum stress (23.9 tons per square inch) and (d) the obtained micro-structure. The quality of forge-welding of Delhi iron pillar is much better than that of the Konārka beams. (Ghosh, 1963: 44)
v1.c27.s2.t3.4
Another iron pillar which had even bigger dimensions than the Delhi iron pillar, belonged to the period of Bhoja (AD 1000-55). Its three broken parts are found at Dhar near Indore; possibly there was a fourth one in Bhoja's capital.
v1.c27.s2.t3.5
Cousens (1902-03) gave a full account of the pillar and its broken parts. The largest piece 24' 3" in length and square in cross-section lies half-buried in Lat Masjid built near the pillar itself in AD 1405. The second piece is 11' 7" in length; its shape is not uniform, 8' 6" being square and 3' 1" octagonal. The third piece lies embedded in the public garden Lalbag; it has a length of 7' 6" and is rectangular in cross-section, the average width being 10-1/4 inches. Several small holes surround the pillar; Cousens was of the opinion that the holes or pits in the body of the Dhar pillar were made as the result of inserting some instruments like crowbars, while the pillar was being forged and welded.
v1.c27.s2.t3.6
Possibly, Bhoja, the king, himself had the pillar erected as a mark of victory. The weight of the pillar is estimated to be seven tons, one ton greater than that of the Delhi iron pillar. The total height has been estimated to be 43' 8" — nearly twice as long as the Delhi iron pillar. It is the largest pillar of its kind, not only in ancient India, but also in the entire ancient world. (Neogi, 1914: 21-26; Sohoni, 1983: 106) The eminent historian, Vincent Smith remarked: "Whilst we marvel at the skill shown by the ancient artificers in forging a great mass of the Delhi pillar, we must give a still greater measure of admiration to the forgotten craftsmen who dealt so successfully in producing the still more ponderous iron mass of the Dhar Pillar monument".
v1.c27.s2.t3.7
Another iron pillar, probably belonging to the fifteenth century AD, is that in the temple of Acaleśwar on Mount Abu in Rajasthan. It is 12' 9" high with a Śaiva trident on its top. This one as well as the Dhar pillar are made of wrought iron. The foregoing achievements amply illustrate how skilful and imaginative were the metalsmiths in India.