Completed post graduation in modern Indian history and Ph.D on the ideology and programme of the national revolutionaries in the 1920s. Taught for four years before joining the National Institute of Science, Technology and Development Studies, New Delhi in 1982. Engaged in research on issues related to history of science and science education in the mid ninteenth and the early twentieth century India. Authored/edited several books including Situating the History of science: Dialogues with Joseph Needham, (Oxford, 1999); Domesticating Modern Science, (Tulika, 2004); Social History of Science in Colonial India, (Oxford, 2007); and UNESCO's History of Humanity, Vol.VII, (Paris, 2008). His most recent book in To Make the Deaf Hear, published in 2007, its Hindi version appeared in 2008 while its Tamil edition came out in 2009. He has been a Fulbright Fellow at the State University of New York and also a Research Associate at REHSEIS, CNRS, Paris.