Spies in monks’ clothing
During the 19th century, fear of invasion from the north led officials in British India to enlist locals to fill in blanks in their maps. Jules Stewart tells the story of the pundits.
The Great Trigonometrical Survey of India was a key instrument of Britain’s 19th-century imperial expansion. The enterprise was launched in 1802 by Colonel William Lambton, an infantry officer, whose plan was to undertake a scientific mapping of India from a spot near Madras to north of the Himalaya.
Lambton’s ingenious scheme consisted of laying out a network of triangles, each drawn from three points of reference and then stacked alongside one another to form a grid. The chain of triangles could then be protracted in any direction across a landmass for the purpose of measuring distance. This took the form of a Great Arc of the Meridian, tracing a line some 2,600 kilometres up the spine of the Indian subcontinent.
With the Empire in rapid expansion, it was crucial to know what lay beyond its frontiers, but this knowledge came to a halt at the foot of the great Himalayan barrier. By the mid-19th century, the survey still had but the vaguest notion of the location of strategic cities such as Lhasa. Similarly, the question of whether the Tsangpo and Brahmaputra rivers were joined at some remote spot was a mystery. And Gilgit, Chilas and Chitral, key outposts of India’s North-West Frontier, remained unexplored. Yarkand was 160 kilometres out of position on the survey’s map and, in fact, the entire landmass of Central Asia was a vast geographical enigma.
Enter Captain Thomas George Montgomerie of the Royal Engineers, who arrived in Bombay in 1850 and joined the survey a year later. At the time, the survey possessed a fairly reliable set of data on some 100,000 square kilometres of trans-Himalayan territory, but this still left a blank on the map roughly the size of India itself. Montgomerie estimated that some 3.6 million square kilometres of unexplored land north of the Himalayan and Karakoram ranges could be penetrated from India. What sent the government’s antennae flailing was the fact that, conversely, this same immense territory was a potential gateway to British India for a foreign invader.