Strabo, Geography (English) (XML Header) [genre: prose] [word count] [Str.]. | ||

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The fourth section would consist of Arabia Felix, the Arabian Gulf, and the whole of Egypt and Ethiopia. Its length bounded by two meridians, one drawn through its most western point, the other through its most eastern; and its breadth by two parallels through its most northern and southern points. For this is the best way to describe the extent of irregular figures, whose length and breadth cannot be determined by their sides.

In general it is to be observed, that length and breadth are to be understood in different ways, according as you speak of the whole or a part. Of a whole, the greater distance is called its length, and the lesser its breadth; of a part, that is to be considered the length which is parallel to the length of the whole, without any regard whether it, or that which is left for the breadth, be the greater distance. The length of the whole habitable earth is measured from east to west by a line drawn parallel to the equator, and its breadth from north to south in the direction of the meridian; consequently, the length of any of the parts ought to be portions of a line drawn parallel to the length of the whole, and their breadth to the breadth of the whole. For, in the first place, by this means the size of the whole habitable earth will be best described; and secondly, the disposition and configuration of its parts, and the manner in which one may be said to be greater or less than another, will be made manifest by thus comparing them. 2.1.33

Eratosthenes, however, measures the length of the
habitable earth by a line which he considers straight, drawn
from the Pillars of Hercules, in the direction of the Caspian
Gates and the Caucasus. The length of the third section,
by a line drawn from the Caspian Gates to Thapsacus,
and of the fourth, by one running from Thapsacus through
Heroopolis to the country surrounded by the Nile: this
must necessarily be deflected to Canopus and Alexandria,
for there is the last mouth of the Nile, which goes by the
name of the Canopic ^{[Note]} or Heracleotic mouth. Whether

therefore these two lengths be considered to form one
straight line, or to make an angle with Thapsacus, certain it is that neither of them is parallel to the length of the
habitable earth; this is evident from what Eratosthenes has
himself said concerning them. According to him the length
of the habitable earth is described by a right line running
through the Taurus to the Pillars of Hercules, in the direction of the Caucasus, Rhodes, and Athens. From Rhodes to
Alexandria, following the meridian of the two cities, he says
there cannot be much less than 4000 stadia, ^{[Note]} consequently there
must be the same difference between the latitudes of Rhodes
and Alexandria. Now the latitude of Heroopolis is about the
same as Alexandria, or rather more south. So that a line,
whether straight or broken, which intersects the parallel of
Heroopolis, Rhodes, or the Gates of the Caspian, cannot be
parallel to either of these. These lengths therefore are
not properly indicated, nor are the northern sections any
better.
2.1.34

We will now return at once to Hipparchus, and see
what comes next. Continuing to palm assumptions of his own
[upon Eratosthenes], he goes on to refute, with geometrical
accuracy, statements which that author had made in a mere
general way. Eratosthenes, he says, estimates that there
are 6700 stadia between Babylon and the Caspian Gates,
and from Babylon to the frontiers of Carmania and Persia
above 9000 stadia; this he supposes to lie in a direct line
towards the equinoctial rising, ^{[Note]} and perpendicular to the common side of his second and third sections. Thus, according
to his plan, we should have a right-angled triangle, with the
right angle next to the frontiers of Carmania, and its hypotenuse less than one of the sides about the right angle!
Consequently Persia should be included in the second section. ^{[Note]}

To this we reply, that the line drawn from Babylon to Carmania was never intended as a parallel, nor yet that which
divides the two sections as a meridian, and that therefore nothing has been laid to his charge, at all events with any just
foundation. In fact, Eratosthenes having stated the number
of stadia from the Caspian Gates to Babylon as above
given, ^{[Note]} [from the Caspian Gates] to Susa 4900 stadia,
and from Babylon [to Susa] 3400 stadia, Hipparchus runs
away from his former hypothesis, and says that [by drawing lines from] the Caspian Gates, Susa, and Babylon,
an obtuse-angled triangle would be the result, whose sides
should be of the length laid down, and of which Susa
would form the obtuse angle. He then argues, that according to these premises, the meridian drawn from the Gates of
the Caspian will intersect the parallel of Babylon and Susa
4400 stadia more to the west, than would a straight line
drawn from the Caspian to the confines of Carmania and
Persia; and that this last line, forming with the meridian of
the Caspian Gates half a right angle, would lie exactly
in a direction midway between the south and the equinoctial
rising. Now as the course of the Indus is parallel to this
line, it cannot flow south on its descent from the mountains, as
Eratosthenes asserts, but in a direction lying between the
south and the equinoctial rising, as laid down in the ancient
charts. But who is there who will admit this to be an obtuse-angled triangle, without also admitting that it contains a
right angle? Who will agree that the line from Babylon to
Susa, which forms one side of this obtuse-angled triangle, lies
parallel, without admitting the same of the whole line as far
as Carmania? or that the line drawn from the Caspian Gates
to the frontiers of Carmania is parallel to the Indus? Nevertheless, without this the reasoning [of Hipparchus] is worth
nothing

Eratosthenes himself also states, [continues Hipparchus, ^{[Note]}]

that the form of India is rhomboidal; and since the whole
eastern border of that country has a decided tendency towards the east, but more particularly the extremest cape, ^{[Note]}
which lies more to the south than any other part of the coast,
the side next the Indus must be the same.

Strabo, Geography (English) (XML Header) [genre: prose] [word count] [Str.]. | ||

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