But instead of being surprized at the differences which obtain between the measurements which have descended to us from the ancients, we ought rather, perhaps, to wonder that they do not differ even more than they are usually found to do from each other. It is true that abundant materials were furnished to the early geographers, by the numerous military and naval expeditions which enterprizing or ambitious states had fitted out for the purposes of conquest or discovery[8]; but the maps and charts which resulted from them were laid down without the aid of astronomy; and the distances between the places described in them were either measured or computed along the roads which the armies traversed, or deduced from the track of vessels along the coast. Major Rennell has observed, that the difference which will generally be found between the measurements of Eratosthenes and Strabo, and those which appear in modern geography, will be that which exists between the measure of a _direct_ line, drawn from one place to another, and that of the _road_ distance between them. “Nothing can speak more strongly to this point,” (says the well-informed and intelligent writer here quoted,) “than the circumstance of Strabo’s giving the number of stades in Nearchus’s coasting navigation for the lengths of the coasts of Persia and Caramania[9].” In fact it was not till the time of Ptolemy that geography began to be placed upon that solid basis on which it now stands so conspicuously; and it certainly appears somewhat singular, that the writers on this subject who flourished between the time of Hipparchus and that of the Alexandrian geographer (among whom were Strabo and Pliny,) should not have availed themselves of the discoveries of the former to check the measurements which appear in their works[10]. Various errors have been pointed out in the geography of Ptolemy; but as it can scarcely be supposed that he had sufficient observations to regulate the position of all the places which he has laid down, we ought not to be surprized at this circumstance. His outline of the Gulf of Syrtis, though it cannot be called correct, is notwithstanding more so than those which have since been given of it; and the prolongation of the gulf at its southern extremity, so erroneously marked in modern charts, as well as the inlet called the Gulf of Zuca, which we have stated does not exist, are neither of them laid down in it at all. It may therefore be said, that the true character of the gulf is much better preserved in the loose outline of Ptolemy than in any other of which we are aware. Whatever may be the reasons which have induced modern geographers to introduce into the Gulf of Syrtis the errors which we have alluded to, it is certain that the best chart which they have hitherto produced of it must undergo a correction of ninety miles in longitude, and upwards of thirty miles in latitude, that is to say, it must part with nearly six thousand square miles of ground,