Xerxes' Pontoon Bridges

From the Modern Library edition of George Rawlinson's translation of The Persian Wars by Herodotus:

[7.34] Towards this tongue of land then, the men to whom the business was assigned carried out a double bridge from Abydos; and while the Phoenicians constructed one line with cables of white flax, the Egyptians in the other used ropes made of papyrus. Now it is seven furlongs across from Abydos to the opposite coast. When, therefore, the channel had been bridged successfully, it happened that a great storm arising broke the whole work to pieces, and destroyed all that had been done.

[7.35] So when Xerxes heard of it he was full of wrath, and straightway gave orders that the Hellespont should receive three hundred lashes, and that a pair of fetters should be cast into it. Nay, I have even heard it said that he bade the branders take their irons and therewith brand the Hellespont. It is certain that he commanded those who scourged the waters to utter, as they lashed them, these barbarian and wicked words: "Thou bitter water, thy lord lays on thee this punishment because thou hast wronged him without a cause, having suffered no evil at his hands. Verily King Xerxes will cross thee, whether thou wilt or no. Well dost thou deserve that no man should honour thee with sacrifice; for thou art of a truth a treacherous and unsavoury river." While the sea was thus punished by his orders, he likewise commanded that the overseers of the work should lose their heads.

[7.36] Then they, whose business it was, executed the unpleasing task laid upon them; and other master-builders were set over the work, who accomplished it in the way which I will now describe.
They joined together triremes and penteconters, 360 to support the bridge on the side of the Euxine Sea, and 314 to sustain the other; and these they placed at right angles to the sea, and in the direction of the current of the Hellespont, relieving by these means the tension of the shore cables. Having joined the vessels, they moored them with anchors of unusual size, that the vessels of the bridge towards the Euxine might resist the winds which blow from within the straits, and that those of the more western bridge facing the Egean might withstand the winds which set in from the south and from the south-east. A gap was left in the penteconters in no fewer than three places, to afford a passage for such light craft as chose to enter or leave the Euxine. When all this was done, they made the cables taut from the shore by the help of wooden capstans. This time, moreover, instead of using the two materials separately, they assigned to each bridge six cables, two of which were of white flax, while four were of papyrus. Both cables were of the same size and quality; but the flaxen were the heavier, weighing not less than a talent the cubit. When the bridge across the channel was thus complete, trunks of trees were sawn into planks, which were out to the width of the bridge, and these were laid side by side upon the tightened cables, and then fastened on the top. This done, brushwood was brought, and arranged upon the planks, after which earth was heaped upon the brushwood, and the whole trodden down into a solid mass. Lastly a bulwark was set up on either side of this causeway, of such a height as to prevent the sumpter-beasts and the horses from seeing over it and taking fright at the water.