and Porus, Abisares intended to join his forces with those of the latter. On this occasion he sent his brother with the other envoys to Alexander, taking with them money and forty elephants as a gift. Envoys also arrived from the independent Indians, and from a certain other Indian ruler named Porus.[699] Alexander ordered Abisares to come to him as soon as possible, threatening that unless he came he would see him arrive with his army at a place where he would not rejoice to see him. At this time Phrataphernes, viceroy of Parthia and Hyrcania, came to Alexander at the head of the Thracians who had been left with him. Messengers also came from Sisicottus, viceroy of the Assacenians, to inform him that those people had slain their governor and revolted from Alexander. Against these he despatched Philip and Tyriaspes with an army, to arrange and set in order the affairs of their land. He himself advanced towards the river Acesines.[700] Ptolemy, son of Lagus, has described the size of this river alone of those in India, stating that where Alexander crossed it with his army upon boats and skins, the stream was rapid and the channel was full of large and sharp rocks, over which the water being violently carried seethed and dashed. He says also that its breadth amounted to fifteen stades; that those who went over upon skins had an easy passage; but that not a few of those who crossed in the boats perished there in the water, many of the boats being wrecked upon the rocks and dashed to pieces. From this description then it would be possible for one to come to a conclusion by comparison, that the size of the river Indus has been stated not far from the fact by those who think that its mean breadth is forty stades, but that it contracts to fifteen stades where it is narrowest and therefore deepest; and that this is the width of the Indus in many places. I come then to the conclusion that Alexander chose a part of the Acesines where the passage was widest, so that he might find the stream slower than elsewhere. CHAPTER XXI. ADVANCE BEYOND THE HYDRAOTES.