ANCIENT FEATS OF ENGINEERING
It is worth taking time to look at some of the most outstanding ancient feats of engineering that have survived to the present day. The Great Pyramid must take first place not only because it was so big, but because it has survived relatively intact for so long.
The examples of domes are particularly interesting, because they are examples of how heavy construction materials like stone, masonry and concrete could be self-supporting, without additional reinforcement. Immense domed buildings were and still are used by people in large numbers and stone will withstand wear and tear and exposure to the elements. The oldest and largest dome was the Pantheon and it remained the largest for more than 1,300 years.
An example of late mediaeval architecture was included to illustrate one of the finest examples of engineering that is not only beautiful, but has survived for 577 years and remains unsurpassed for this type of construction. This dome was finished in the period now referred to as the Renaissance and although this would connote culture and art, there is no doubt that there was also a renaissance in engineering and technology, some of which had not really progressed much in the previous 1,300 years and the knowledge of many ancient methods had been lost or forgotten.
Iron was known in ancient times and the 7.21 metre high iron pillar, weighing about 6 tonnes, illustrated in the photo on the left, is located in Delhi, India[1]. This remarkable example of iron has survived unprotected for more than 1,600 years. Research[2] has shown that it was originally erected to honour Lord Vishnu at a Hindu temple complex located at modern Udayagiri, about 50 km east of Bhopal, by King Chandragupta II, whose reign has been dated to CE 375 – 414. Its condition is a tribute to the Indian metallurgists of that time. A study of the metallurgy indicates that is has a high phosphorus content, which causes the formation of a protective film. Relatively little use was made of iron and steel as a structural or reinforcement material, until methods of smelting had advanced in Europe in the 17th century. An example of the early use of iron in the 19th century for the construction of a large dome has been added to illustrate another early approach to the engineering of domes, before the use of steel.
The last item in the list is a dome made of reinforced concrete. It is a fine example of architecture and engineering that provides a large space, which has been in use for public events for the past 100 years. An analogy may be drawn from the use of reinforced concrete that applies to fibre-reinforced plastics. This encourages us to explore the possibilities of combining two very different materials to create a composite material that exceeds the properties of both of its components, thus making possible many new products.
1. Iron Pillar of Delhi, see URL: https://en.wikipedia.org/wiki/Iron_pillar_of_Delhi
2. Detailed information about this pillar is provided in a paper by R. Balasubramaniam and Meera I. Dass, On the astronomical significance of the Delhi iron pillar, CURRENT SCIENCE, Vol. 86, NO. 8, 25 April 2004, pp 1134-1142. The inscription provides information that the pillar was erected as a standard of Vishnu (Vishnuordhvajah) at the hill of the footprint of Vishnu (Vishnupadagiri) by King Chandragupta II Vikramaditya, who reigned ca. 375 – 415 CE. This has been confirmed as the original location of the pillar at a temple complex located at modern Udayagiri about 50 km east of Bhopal in Central India.