Jean Baptiste François Joseph de Warren

While working as a surveyor in the Great Trigonometrical Survey he rediscovered what became the Kolar Gold Fields and in later life he documented Indian astronomy and time-keeping in his book Kala Sankalita.

He also examined the effects of humidity by constructing a hygrometer that made use of the beards of a local grass called Panimooloo Heteropogon contortus.

Leaving his son to study in France, he returned to settle in Pondicherry and work on a book on the methods of timekeeping and calendar making in southern India.

Among the calculations that Warren documented was the computation of lunar eclipses by a Pondicherry-based calendar maker who used shells placed on the ground and coded formulae.

[6] Warren died in Pondicherry on 9 February 1830 and a book on his life was written by his son Edouard - L'Inde Anglaise en 1843.