[1]The stade of Strabo has been estimated by Major Rennell, in his admirable treatise on the itinerary stade of the Greeks, at 700 to a geographical degree; and 930 stades will, on this computation, be equal to 100½[a] Roman miles, or 80⅒ geographic miles. While the dimensions of the diameter, 1500 stades, will be equal to 162½ Roman miles, or 128⁵⁷⁄₁₀₀ geographic.
[a]The geographical and Roman miles differ (says Shaw, on the authority of D’Anville) as 60 is to 75½, that is, 60 geographical miles and 75½ Roman miles are equal to one degree of a great circle. The Roman mile is consequently one-fifth less than a geographic mile.—Vol. i. p. 30.
[2]Ἡ δε μεγαλη Συρτις τον μεν κυκλον εχει σταδιων εννακοσιων τριακοντα που· την δ᾽ επι τον μυχον διαμετρον χιλιων πεντακοσιων· τοσουτον δε που και το του στοματος πλατος.—Lib. xvii. p. 385.
[3]In the second book, however, the measurements given by Strabo are more consistent; for he tells us that the circumference of the Greater Syrtis is (according to Eratosthenes) five thousand stadia, or 428⁴⁵⁄₁₀₀ geographic mile[a]; and its depth, from the Hesperides to Automala, and the limits of the Cyrenaica, one thousand eight hundred, or 154²⁹⁄₁₀₀ geographic miles. Others, he adds, make the circumference four thousand stadia, 342⁸⁸⁄₁₀₀ geographic miles; and the depth one thousand five hundred stadia, or 128⁵⁷⁄₁₀₀ geographic miles; the same, he says, as the breadth of the gulf at its mouth.—Lib. xi. p. 123.
[a]At the rate of 700 stades to a degree.
[4]This estimate of the circumference is deduced from the camel-track, corrected by observations; and the accuracy to which this mode of computation may be brought by care and attention, and by making the proper allowances, will be seen in the examples which we shall hereafter submit of it.
[5]If, however, we take the measurements just quoted from the second book of Strabo, as those which he intended to be received in the present case, we shall find that the 428⁴⁵⁄₁₀₀ miles, resulting from the 5000 stadia of Eratosthenes, come very near the truth. The other measurements, however, are far from correct. It will be observed that the diameter given in this place is the same with that mentioned in the second book (1500 stadia).
[6]Inde Syrtis Major, circuitu DCXXV. aditu autem, CCCXIII. M. Passuum.—Nat. Hist. lib. v. cap. 4.
[7]Nec procul ante Oppidum (Berenice) fluvius Lethon, lucus sacer, ubi Hesperidum horti memorantur. Abest a Lepti CCCLXXXV. M. P.—(Lib. v. cap. 5.)
[8]Sesostris is said to have recorded his march in maps, and to have given copies of them not only to the Egyptians, but to the remote and uninformed inhabitants of Scythia, who viewed them with the greatest astonishment. The expeditions of Alexander furnished the materials for an interesting survey, a copy of which was given to Patroclus the geographer; it was from the work of Patroclus that Eratosthenes derived his principal materials in constructing the Oriental part of his map of the world, and it is frequently quoted both by Strabo and Pliny.