Strabo, Geography
H.C. Hamilton, Esq., W. Falconer, M.A., Ed.

Aristobulus, however, says, that rain and snow fall only on the mountains and the country immediately below them, and that the plains experience neither one nor the other, but are overflowed only by the rise of the waters of the rivers; that the mountains are covered with snow in the winter; that the rains set in at the commencement of spring, and continue to increase; that at the time of the blowing of the Etesian winds they pour down impetuously, without intermission, night and day till the rising of Arcturus,¹ and that the rivers, filled by the melting of the snow and by the rains, irrigate the flat grounds.

These things, he says, were observed by himself and by others on their journey into India from the Paropamisadæ. This was after the setting of the Pleiades,² and during their stay in the mountainous country in the territory of the Hypasii, and in that of Assacanus during the winter. At the beginning of spring they descended into the plains to a large city called Taxila,³ thence they proceeded to the Hydaspes and the country of Porus. During the winter they saw no rain, but only snow. The first rain which fell was at Taxila. After their descent to the Hydaspes and the conquest of Porus, their progress was eastwards to the Hypanis, and thence again to the Hydaspes. At this time it rained continually, and particularly during the blowing of the Etesian winds, but at the rising of Arcturus the rains ceased. They remained at the Hydaspes while the ships were constructing, and began their voyage not many days before the setting of the Pleiades, and were occupied during the whole autumn, winter, and the ensuing spring and summer, in sailing down the river, and arrived at Patalene⁴ about the rising of the Dog-Star;⁵ during the passage down the river, which lasted ten months, they did not experience rain at any place, not even when the Etesian winds were at their height, when the rivers were full and the plains overflowed; the sea could not be navigated on account of the blowing of contrary winds, but no land breezes succeeded.