Bangalore, July 9 - Designers of the 17th century Taj Mahal in India, the finest piece of Mughal architecture, employed the same unit of measurement used by the Harappan civilization of 2000 BC, according to a new study reported in the latest issue of Current Science.

The study by R. Balasubramaniam of the Indian Institute of Technology, Kanpur, has for the first time shown that the unit of length called 'angulam' -- mentioned in Kautilya's treatise 'Arthasastra' dated 300 BC -- was used without a break by Indian builders for over 3,900 years until the British imposed their units in the 18th century.

The ancient 'angulam' has been found to be equal to 1.763 modern centimetres, according to Balasubramaniam, a professor of materials and metallurgical engineering. He has carried out dimensional analysis of some of India's historical structures, built during different times, to identify the measuring units used in their engineering plans.

He says he was surprised that 'angulam' and its multiples 'vitasti' (12 angulams) and 'dhanus' (108 angulams) have been used as the unit of measurement right from the Harappan times till the pre-modern era when the Taj was built.

Balasubramaniam, who last year studied the dimensions of the 1,600-year-old Delhi Iron Pillar at the Qutub Minar complex, found that 'angulam' and its multiple 'dhanus' were used as the basic units of length in its design.