 Burrard suggested that anomalies in latitude found by the Survey in the early 1800s parallel to the mountains to the north might be caused by a large mass below the Indo-Gangetic Plain.New four-pendulum-based equipment to measure the gravitational force was modified to suit and, between 1903 and 1908, Lenox-Conyngham collected gravitational data across the subcontinent.The data showed a negative relative gravitational component in the region of the Plain, a fact readily apparent in modern measurements (see image).