52 GREAT TRIGONOMETRICAL SURVEY OF INDIA. 



one. 112 feet in height, was usefully converted into an observing 

 station, enabling a connexion to be established with the triangulation 

 of Lieutenant Woodthorpe, who was carrying on a topographical 

 survey in the neighbourhood. The work of the season extended 

 over a distance of 53 miles, along the banks of the Brahmaputra to 

 within a few miles of Sadiya. During the following season 

 (1877-78) endeavours were made to extend the triangulation of the 

 region between the Subansiri and the Dihong, so as to ascertain 

 which of the two formed the continuation of the Sanpo river of Tibet. 

 As it was practically impossible to venture far across the frontier, 

 Lieutenant Harman was directed to measure the discharges of the 

 Subansiri, the Dihong, the Dibong, and the Bramaputra in order 

 to try and solve the question by ascertaining the magnitude of the 

 volume of water in each river, and thus obtaining indirect evidence 

 on the question at issue. 



In company with Captain "Woodthorpe, Lieutenant Harman pro- 

 ceeded to the Miri Hills, between the Subansiri and Dihong rivers, 

 and succeeded in sketching about 1,500 miles on the half-inch 

 scale. This included a portion of the Dihong river, higher than any 

 previously surveyed, but not sufficiently high to show whether the 

 stream is the continuation of the Sanpo or not. He next com- 

 menced to measure the river discharges, taking observations of the 

 following: — (1) the Subansiri river; (2) the Brahmaputra, at a 

 point three miles from Dibrugarh and below the junction of the 

 Dihong and Dibong rivers; (3) the united stream of the Dihong 

 and Dibong rivers, one mile below their junction and one mile above 

 their junction with the Bramaputra ; (4) the Dibong river, at one 

 mile above its junction with the Dihong and half a mile below the 

 junction of the Sensri river with it; (5) the Brahmaputra river, 

 about nine miles above Sadiya and half a mile below the junction 

 of the united stream of the Tengapani and Noa Dihing rivers ; and 

 (6) the united stream of the two latter rivers, at about 200 yards 

 below their junction. 



The full details of these interesting operations, including the 

 sectional measurements and the calculation of discharges, have been 

 published by the Asial c Socii ty of Bengal* The general effect is 

 to show that the volume of water in the Dihong is from two to 



* Sec J. A.S. B., Vol. XLVIII., Pt. 2, No. I.. 1879. The measurements, in connexion 

 with the earlier ones by Bedford and Wileox, are also discussed in General Walker's 

 paper on the Hydrography uf S.E. Tibet (see Proceedings Royal Geographical 

 Society, p. 581 1888 



