To accomplish this extensive design, Alexander had sent one of his officers to Phoenicia with 500 talents (about 106,830_l_.) to buy slaves fit for the oar, and hire mariners.  These preparations were so extensive, that it seems highly probable that Alexander meant to conquer Arabia, as well as explore the navigation of the Arabian Gulf; and indeed his plan and policy always were to unite conquest with discovery.  As soon as he had put these preparations in a proper train, he again embarked, and sailed down the Euphrates as far as Pallacopas.  The immediate object of this voyage is not exactly known.  As the Euphrates flows over the adjacent country at certain seasons, the Persian monarchs had cut a canal at Pallacopas, which diverted its superfluous waters into a lake, where they were employed to flood the land.  This and similar canals had been long neglected; but as Alexander seems to have fixed on Babylon as the future capital of his empire, it was necessary to restore the canals to their original utility, in order that the ground on both sides of the Euphrates might be drained or flooded at the proper season.  This may have been the only object of Alexander’s voyage, or it may have been connected with the projected voyage of Nearchus.  It is certain, however, that by his directions the principal canal was much improved; indeed it was in reality cut in a more convenient and suitable place; for the soil where it had been originally cut was soft and spongy, so that much labour and time were required to restore the waters to their course, and secure its mouth in a safe and firm manner.  A little lower down, the soil was much more suitable, being strong and rocky; here then Alexander ordered the opening of the canal to be made:  he afterwards entered it with his fleet, and surveyed the whole extent of the lake with which it communicated.  On the Arabian side of the Gulf, he ordered a city to be built:  immediately afterwards he returned to Babylon, where he died.

In the mean time, and while Nearchus was at Babylon, three vessels were sent down the Arabian side of the Gulf, to collect such information as might be useful to him in his projected voyage.  One was commanded by Archias, who proceeded as far as Tylos, or Bahrein, the centre of the modern pearl fishery.  A short distance from the mouth of the Euphrates, Archias discovered two islands; on one of which a breed of goats and sheep was preserved, which were never killed, except for the purpose of sacrifice.  The second vessel sailed a little way round the coast of Arabia.  The third, which was commanded by Hiero of Soli, went much farther than either of the other two, for it doubled Cape Mussendoon, sailed down the coast below Moscat, and came in sight of Cape Ras-el-hed:  this cape he was afraid to double.  On his return he reported that Arabia was much more extensive than had been imagined.  None of these vessels proceeded so far as to be of much service to Nearchus, or to carry into effect the grand object of Alexander:  for his instructions to Hiero in particular were, to circumnavigate Arabia; to go up the Red Sea; and reach the Bay of Hieropolis, on the coast of Egypt.  All these vessels were small, having only fifty oars, and therefore not well calculated for such a long and hazardous navigation.