and the Kaïkos and the Maiandros and the other rivers of Asia which fall into the inland sea were united, they could not be compared in volume of water with one of the Indian rivers, and much less with the Ganges, which is the greatest of them all, and with which neither the volume of the Egyptian Nile, nor the Istros (Danube) which flows through Europe, can be for a moment compared. Nay, the whole of those rivers if combined into one would not be equal to the Indus, which is already a large river where it issues from its springs, and which after receiving as tributaries fifteen rivers,[90] all greater than those of Asia, enters the sea still retaining its own name. Let these remarks which I have made about the country of the Indians suffice for the present, while I reserve all other particulars for my description of India. _Chapter VII.—The bridging of rivers_ In what manner Alexander made his bridge over the Indus neither Aristoboulos nor Ptolemy, the authorities whom I chiefly follow, have given any account; nor can I decide for certain whether the passage was bridged with boats, as was the Hellespont by Xerxes and as were the Bosporos and the Istros by Darius,[91] or whether the bridge he made over the river was one continuous piece of work. I incline, however, to think that the bridge must have been made of boats,[92] for neither would the depth of the river have admitted the construction of an ordinary kind of bridge, nor could a work so vast and difficult have been executed in so short a time. But if the passage was bridged with boats I cannot decide whether the vessels being fastened together with cables and anchored in a row sufficed to form a bridge as did those by which, as Herodotos the Halikarnassian says, the Hellespont was joined, or whether the method was that which is used by the Romans in bridging the Istros and the Keltic Rhine,[93] and by which they bridged the Euphrates and the Tigris as often as necessity required. Since, however, the Romans, as far as my knowledge goes, have found that the bridging of rivers by boats is the most expeditious method of crossing them, I think it worth a description here. The vessels at a preconcerted signal are let go from their moorings and rowed down stream not prow but stern foremost. The current of course carries them downward, but a small pinnace furnished with oars holds them back till they settle into their appointed place. Then baskets of wicker work, pyramid-shaped and filled with rough stones, are lowered into the river from the prow of each vessel to make it hold fast against the force of the current. As soon as one of those vessels has been held fast another is in the same way anchored with its prow against the stream as far from the first as is commensurate with their bearing the strain of what is put upon them. On both of them beams of wood are rapidly laid lengthwise, and on these again planks are placed crosswise to bind them together.