[38.] At the same time the Rhodians went to war with the Byzantines, for reasons which I Rhodian and Byzantium war, 220-219 B.C. must now describe.
As far as the sea is concerned, Byzantium occupies a position the most secure and in every way the most Advantages of the situation of Byzantium. advantageous of any town in our quarter of the world: while in regard to the land, its situation is in both respects the most unfavourable. By sea it so completely commands the entrance to the Pontus, that no merchant can sail in or out against its will. The Pontus therefore being rich in what the rest of the world requires for the support of life, the Byzantines are absolute masters of all such things. For those commodities which are the first necessaries of existence, cattle and slaves, are confessedly supplied by the districts round the Pontus in greater profusion, and of better quality, than by any others: and for luxuries, they supply us with honey, wax, and salt-fish in great abundance; while they take our superfluous stock of olive oil and every kind of wine. In the matter of corn there is a mutual interchange, they supplying or taking it as it happens to be convenient. Now the Greeks would necessarily have been excluded entirely from traffic in these articles, or at least would have had to carry it on at a loss, if the Byzantines had adopted a hostile attitude, and made common cause formerly with the Gauls, or still more at this time with the Thracians, or had abandoned the place altogether: for owing to the narrowness of the strait, and the number of the barbarians along its shores, it would have become entirely impassable to our ships. The Byzantines themselves probably feel the advantages of the situation, in the supplies of the necessaries of life, more than any one else; for their superfluity finds a ready means of export, and what they lack is readily imported, with profit to themselves, and without difficulty or danger: but other people too, as I have said, get a great many commodities by their means. As common benefactors therefore of all Greece they might justly expect, not only gratitude, but the united assistance of Greeks, when threatened by the barbarians.
But since the peculiar natural advantages of this site are generally unknown, because it lies somewhat outside the parts of the world ordinarily visited; and since it is an universal wish to be acquainted with things of this sort, by ocular inspection, if possible, of such places as have any unusual or remarkable features; or, if that is impossible, by having in our minds some ideas or images of them as like the truth as may be, I must now state the facts of the case, and what it is that makes this city so eminently rich and prosperous.
[39.] The sea called “The Pontus” has a circumference of twenty-two thousand stades, and two mouths The Pontus. diametrically opposite to each other, the one opening into the Propontis and the other into the Maeotic Lake; which latter also has itself a circumference of eight thousand stades. Into these two basins many great rivers discharge themselves on the Asiatic side, and still larger and more numerous on the European; and so the Maeotic lake, as it gets filled up, flows into the Pontus, and the Pontus into the Propontis. The mouth of the Maeotic lake is called the Cimmerian Bosporus, about thirty stades broad and sixty long, and shallow all over; that of the Pontus is called the Thracian Bosporus, and is a hundred and twenty stades long, and of a varying breadth. Between Calchedon and Byzantium the channel is fourteen stades broad, and this is the entrance at the end nearest the Propontis. Coming from the Pontus, it begins at a place called Hieron, at which they say that Jason on his return voyage from Colchis first sacrificed to the twelve gods. This place is on the Asiatic side, and its distance from the European coast is twelve stades, measuring to Sarapieium, which lies exactly opposite in Thrace. There are two causes which account for the fact that the waters, both of the Maeotic lake and the Pontus, continually flow outwards. One is patent at once to every observer, namely, that by the continual discharge of many streams into basins which are of definite circumference and content, the water necessarily is continually increasing in bulk, and, had there been no outlet, would inevitably have encroached more and more, and occupied an ever enlarging area in the depression: but as outlets do exist, the surplus water is carried off by a natural process, and runs perpetually through the channels that are there to receive it. The second cause is the alluvial soil brought down, in immense quantities of every description, by the rivers swollen from heavy rains, which forms shelving banks and continually forces the water to take a higher level, which is thus also carried through these outlets. Now as this process of alluvial deposit and influx of water is unceasing and continuous, so also the discharge through the channels is necessarily unceasing and continuous.
These are the true causes of the outflow of the Pontus, which do not depend for their credit on the stories of merchants, but upon the actual observation of nature, which is the most accurate method discoverable.
[40.] As I have started this topic I must not, as most historians do, leave any point undiscussed, or only barely stated. My object is rather to give information, and to clear up doubtful points for my readers. This is the peculiarity of the present day, in which every sea and land has been thrown open to travellers; and in which, therefore, one can no longer employ the evidence of poets and fabulists, as my predecessors have done on very many points, “offering,” as Heraclitus says, “tainted witnesses to disputed facts,”—but I must try to make my narrative in itself carry conviction to my readers.
I say then the Pontus has long been in process of being filled up with mud, and that this process is actually going on now: and further, that in process of time both it and the Propontis, assuming the same local conditions to be maintained, and the causes of the alluvial deposit to continue active, will be entirely filled up. For time being infinite, and the depressions most undoubtedly finite, it is plain that, even though the amount of deposit be small, they must in course of time be filled. For a finite process, whether of accretion or decrease, must, if we presuppose infinite time, be eventually completed, however infinitesimal its progressive stages may be. In the present instance the amount of soil deposited being not small, but exceedingly large, it is plain that the result I mentioned will not be remote but rapid. And, in fact, it is evident that it is already taking place. The Maeotic lake is already so much choked up, that the greater part of it is only from seven to five fathoms deep, and accordingly cannot any longer be passed by large ships without a pilot. And having moreover been originally a sea precisely on a level with the Pontus, it is now a freshwater lake: the sea-water has been expelled by the silting up of the bottom, and the discharge of the rivers has entirely overpowered it. The same will happen to the Pontus, and indeed is taking place at this moment; and though it is not evident to ordinary observers, owing to the vastness of its basin, yet a moderately attentive study will discover even now what is going on.
[41.] For the Danube discharging itself into the Pontus by several mouths, we find opposite it a bank formed by the mud discharged from these mouths extending for nearly a thousand stades, at a distance of a day’s sail from the shore as it now exists; upon which ships sailing to the Pontus run, while apparently still in deep water, and find themselves unexpectedly stranded on the sandbanks which the sailors call the Breasts. That this deposit is not close to the shore, but projected to some distance, must be accounted for thus: exactly as far as the currents of the rivers retain their force from the strength of the descending stream, and overpower that of the sea, it must of course follow that to that distance the earth, and whatever else is carried down by the rivers, would be projected, and neither settle nor become fixed until it is reached. But when the force of the currents has become quite spent by the depth and bulk of the sea, it is but natural that the soil held in solution should settle down and assume a fixed position. This is the explanation of the fact, that, in the case of large and rapid rivers, such embankments are at considerable distances, and the sea close in shore deep; while in the case of smaller and more sluggish streams, these sandbanks are at their mouths. The strongest proof of this is furnished by the case of heavy rains; for when they occur, rivers of inferior size, overpowering the waves at their mouths, project the alluvial deposit out to sea, to a distance exactly in proportion to the force of the streams thus discharging themselves. It would be mere foolish scepticism to disbelieve in the enormous size of this sandbank, and in the mass of stones, timber, and earth carried down by the rivers; when we often see with our own eyes an insignificant stream suddenly swell into a torrent, and force its way over lofty rocks, sweeping along with it every kind of timber, soil, and stones, and making such huge moraines, that at times the appearance of a locality becomes in a brief period difficult to recognise.[222]
[42.] This should prevent any surprise that rivers of such magnitude and rapidity, flowing perpetually instead of intermittently, should produce these effects and end by filling up the Pontus. For it is not a mere probability, but a logical certainty, that this must happen. And a proof of what is going to take place is this, that in the same proportion as the Maeotic lake is less salt than the Pontus, the Pontus is less so than the Mediterranean. From which it is manifest that, when the time which it has taken for the Maeotic lake to fill up shall have been extended in proportion to the excess of the Pontic over the Maeotic basin, then the Pontus will also become like a marsh and lake, and filled with fresh water like the Maeotic lake: nay, we must suppose that the process will be somewhat more rapid, insomuch as the rivers falling into it are more numerous and more rapid. I have said thus much in answer to the incredulity of those who cannot believe that the Pontus is actually being silted up, and will some day be filled; and that so vast a sea will ever become a lake or marsh. But I have another and higher object also in thus speaking: which is to prevent our ignorance from forcing us to give a childish credence to every traveller’s tale and marvel related by voyagers; and that, by possessing certain indications of the truth, we may be enabled by them to test the truth or falsehood of anything alleged by this or that person.
[43.] I must now return to the discussion of the excellence of the site of Byzantium. Site of Byzantium. The length of the channel connecting the Pontus and Propontis being, as I have said, a hundred and twenty stades, and Hieron marking its termination towards the Pontus, and the Strait of Byzantium that towards the Propontis,—half-way between these, on the European side, stands Hermaeum, on a headland jutting out into the channel, about five stades from the Asiatic coast, just at the narrowest point of the whole channel; B.C. 512. where Darius is said to have made his bridge of ships across the strait, when he crossed to invade Scythia. In the rest of the channel the running of the current from the Pontus is much the same, owing to the similarity of the coast formation on either side of it; but when it reaches Hermaeum on the European side, which I said was the narrowest point, the stream flowing from the Pontus, and being thus confined, strikes the European coast with great violence, and then, as though by a rebound from a blow, dashes against the opposite Asiatic coast, and thence again sweeps back and strikes the European shore near some headlands called the Hearths: thence it runs rapidly once more to the spot on the Asiatic side called the Cow, the place on which the myth declares Io to have first stood after swimming the channel. Finally the current runs from the Cow right up to Byzantium, and dividing into two streams on either side of the city, the lesser part of it forms the gulf called the Horn, while the greater part swerves once more across. But it has no longer sufficient way on it to reach the opposite shore on which Calchedon stands: for after its several counter-blows the current, finding at this point a wider channel, slackens; and no longer makes short rebounds at right angles from one shore to the other, but more and more at an obtuse angle, and accordingly, falling short of Calchedon, runs down the middle of the channel.