The line of his march from the
Hellespont till the final defeat of Darius, and his pursuit of that
monarch, had put him in possession of tolerably accurate knowledge of the
northern and western boundaries; the southern provinces alone remained to
be explored: they had indeed submitted to his arms; but they were still,
for all the purposes of government and commerce, unknown.
"To obtain the information necessary for the objects they had in view, he
ordered Craterus, with the elephants and heavy baggage, to penetrate
through the centre of the empire, while he personally undertook the more
arduous task of penetrating the desert of Gadrosia, and providing for the
preservation of the fleet. A glance over the map will show that the route
of the army eastward, and the double route by which it returned, intersect
the whole empire by three lines, almost from the Tigris to the Indus:
Craterus joined the division under Alexander in the Karmania; and when
Nearchus, after the completion of his voyage, came up the Posityris to
Susa, the three routes through the different provinces, and the navigation
along the coast, might be said to complete the survey of the empire."
The two divisions of his army were accompanied on their return to Susa by
Beton and Diognetus, who seem to have united the character and duties of
soldiers and men of science; or, perhaps, were like the quarter-masters-
general of our armies.
