In considering the dimensions which have come down to us of the Greater Syrtis, those allotted to it by Strabo (in the seventeenth book) are so singularly inconsistent with each other, that there appears to be no possible mode of reconciling the measurements he has given of its diameter, with those which he has in the same place ascribed to its circumference, without material alterations in the text. “The circumference of the Greater Syrtis” (observes the geographer) “is about nine hundred and thirty stadia[1]; and its diameter, at the bottom of the Gulf, is one thousand five hundred stadia: the breadth of the entrance (or mouth) is about the same[2]:” that is, about fifteen hundred stadia. Here we have a circumference considerably less than its diameter, and no way of getting rid of a difficulty so formidable to mathematicians, without making such decided alterations in the text as no sober-minded editor would hazard[3]. Various readings have been given, by different commentators, of this passage; but it will be useless to compare their several merits; since both the measurements in question will be found to be no less inconsistent with the truth than they have been seen to be with each other. For the actual circumference of the gulf of the Greater Syrtis may be estimated at four hundred and twenty-two geographic miles, and its diameter at two hundred and forty-six[4]: so that it would be necessary to alter both the circumference and diameter given by Strabo before any use could be made of his dimensions; and then the measurements must be taken on the authority of the commentators, since they would be no longer those of the geographer. In short, the difficulty appears to be scarcely surmountable; for though it is evident that the passage is not as Strabo left it, we have no sufficient data for deciding what it really was originally[5]. The measurements given by Pliny are somewhat nearer the truth[6]; indeed his diameter of the gulf may be considered as remarkably accurate; for it is stated at three hundred and thirteen Roman miles, equal to two hundred and forty-eight and a quarter geographic miles, and there is consequently no more than two miles and a quarter difference between these dimensions and the actual diameter. His circumference, however, is not by any means so accurate; it is given at six hundred and twenty-five Roman miles, which are equal to four hundred and ninety-four geographic miles, and will therefore leave a difference of seventy-two geographic miles between this measurement of the circuit and the actual one. The difference also exists on the wrong side; that is to say, the whole distance of Pliny is not only much more than the actual distance by observations, but much more than the actual road-distance, which is the longest which can be allowed. The diameter of the gulf, already stated, of this author, will be found to coincide remarkably well with the measurement which may be deduced from the distance he has given us