The Great Trigonometrical Survey (Great Trigonometrical Survey) raive basa raive nechinangwa chekuyera nyika yese yeIndia nehunyanzvi hwesayenzi. Yakatanga muna 1802 nemukuru wechiuto William Lambton, pasi peEast India Company. Pasi pehutungamiri hwemutsivi wake, George Everest, chirongwa ichi chakaitwa mutoro weSurvey of India. Everest yakatsiviwa naAndrew Scott Waugh uye mushure ma1861 chirongwa ichi chakatungamirwa naJames Walker, uyo akaona kupera kwayo kwekutanga muna 1871.
kuyera nyika yose yeIndia