longest— namely, the Indus and the Brahmaputra — take their rise in this trough lying on the north of the double wall of the Himalayas; while the third, the Ganges, receives its waters from their southern slopes.
Indus and Sutlej.–The Indus, with its mighty feeder the Sutlej, and the Brahmaputra rise not very far from each other, in lonely valleys, which are separated from India by mountain barriers 15,000 feet high. The Indus and the Sutlej first flow westwards. Then, turning south, through openings in the Himalayas, they join with shorter rivers in the Punjab, and their united stream falls into the Indian Ocean after a course of 1 800 miles.
Brahmaputra.–The Brahmaputra, on the other hand, strikes to the east, flowing behind the Himalayas until it searches out a passage for itself through their clefts at the north-eastern corner of Assam. It then turns sharply round to the west, and afterwards to the south, and so finally reaches the Bay of Bengal. Like the Indus, it has a course of about 1800 miles. Thus, while the Indus and the Brahmaputra rise close to each other behind the Himalayas, and run an almost equal course, their mouths lie 1500 miles apart, on the opposite sides of India. Both of them have a long secret existence in the trough between the double mountain wall before they pierce through the hills ; and they bring to the Indian plains the drainage from the northern slopes of the Himalayas. Indeed, the first part of the course of the Brahmaputra is still unexplored. It bears the name of the Sampu for nearly a thousand miles of its passage behind the Himalayan wall, and it is not till it bursts through the mountains into India that the noble stream receives its Sanskrit name of Brahmaputra, the son of Brahma or God.
The Ganges and its great tributary the Jumna collect the drainage from the southern slopes of the Himalayas ; they join their waters to those of the Brahmaputra as they approach the sea, and, after a course of 1 500 miles, enter the Bay of Bengal by a vast network of channels.
Second Region: The River Plains.–The wide plains watered by the Himalayau rivers form the second of the four regions into which I have divided India. They extend from
