Cayster, the Caïcus, the Maeander, and all the other[661] rivers of Asia which discharge their waters into the midland sea were all put together, they would not be worthy of comparison for volume of water with one of the Indian rivers. Not only do I mean the Ganges, which is the largest, and with which neither the water of the Egyptian Nile nor the Ister flowing through Europe is worthy to compare; but if all those rivers were mingled together they would not even then become equal to the river Indus, which is a large river as soon as it issues from its springs, and after receiving fifteen rivers,[662] all larger than those in the province of Asia, discharges its water into the sea, retaining its own name and absorbing those of its tributaries. Let these remarks which I have made about India suffice for the present, and let the rest be reserved for my “Description of India.” CHAPTER VII. METHOD OF BRIDGING RIVERS. How Alexander constructed his bridge over the river Indus, is explained neither by Aristobulus nor Ptolemy, authors whom I usually follow; nor am I able to form a decided opinion whether the passage was bridged with boats, as the Hellespont was by Xerxes and the Bosporus and the Ister were by Darius,[663] or whether he made a continuous bridge over the river. To me it seems probable that the bridge was made of boats; for the depth of the water would not have admitted of the construction of a regular bridge, nor could so enormous a work have been completed in so short a time.[664] If the passage was bridged with boats, I cannot decide whether the vessels being fastened together with ropes and moored in a row were sufficient to form the bridge, as Herodotus the Halicarnassian says the Hellespont was bridged, or whether the work was effected in the way in which the bridge upon the Ister and that upon the Celtic Rhine[665] are made by the Romans, and in the way in which they bridged the Euphrates and Tigres, as often as necessity compelled them. However, as I know myself, the Romans find the quickest way of making a bridge to be with vessels; and this method I shall on the present occasion explain, because it is worth describing. At a pre-concerted signal they let the vessels loose down the stream, not with their prows forward, but as if backing water.[666] As might naturally be expected, the stream carries them down, but a skiff furnished with oars holds them back, until it settles them in the place assigned to them. Then pyramidal wicker-baskets made of willow, full of unhewn stones, are let down into the water from the prow of each vessel, in order to hold it up against the force of the stream. As soon as any one of these vessels has been held fast, another is in the same way moored with its prow against the stream, distant from the first as far as is consistent with their supporting what is put upon them. On both of them are placed pieces of timber with sharp ends