89. This memorial was made of him who constructed the bridge: and Darius, after he had rewarded Mandrocles with gifts, passed over into Europe, having first commanded the Ionians to sail into the Pontus as far as the river Ister, and when they arrived at the Ister, there to wait for him, making a bridge meanwhile over the river; for the chief of his naval force were the Ionians, the Aeolians and the Hellespontians. So the fleet sailed through between the Kyanean rocks and made straight for the Ister; and then they sailed up the river a two days’ voyage from the sea and proceeded to make a bridge across the neck, as it were, of the river, where the mouths of the Ister part off. Darius meanwhile, having crossed the Bosphorus on the floating bridge, was advancing through Thrace, and when he came to the sources of the river Tearos he encamped for three days. 90. Now the Tearos is said by those who dwell near it to be the best of all rivers, both in other respects which tend to healing and especially for curing diseases of the skin 635