In this history of the British surveys of India, focusing especially on the Great Trigonometrical Survey (GTS) undertaken by the British East India Company, the author relates how imperial Britain employed modern scientific survey techniques not only to create and define the spacial inmage of its Indian empire, but also to legitimate its colonialist activities as triumphs of liberal, rational science bringing "Civilisation" to irrational, mystical and despotic Indians. The reshaping of cartographic technologies in Europe into their modern form played a key role in the use of the GTS as an instrument of British cartographic control over India. In analyzing this reconfiguration, the author undertakes a detailed critical analysis of the foundations of modern cartography.