This book is about modern sciences like mathematics, astronomy, physics, chemistry, botany and medicine in ancient India. The book gives copious references, and often refers to original texts like the Rig Veda and Atharva Veda. Extracts from Some original texts have been often translated in this book, for example Kanada's Vaisheshika sutras discussing kinetic and potential energy, or the Rig Veda and the Chandogya Upanishad for heiocentric model of solar system. In the chapter for mathematics, many earliest contibution in mathematics have been traced to Indian texts like the Shulba Sutras. In the chapter on medicine, the book exahusts medicine in Atharva Veda for the first time. The book also traces in western literature, how Indian knowledge reached the West. It is a source-book for any future work on science in ancient India.