One of the most important and complete surveys of the Roman empire (the idea of which, as has been already stated, was first formed by Julius Cæsar) was begun and finished in the reign of Antoninus, and is well known under the appellation of his Itinerary. It has, indeed, been objected to this date of the Itinerary, that it contains places which were not known in the time of Antonine, and names of places which they did not bear till after his reign; thus mention is made of the province of Arcadia in Egypt, and of Honorius in Pontus, so styled in honor of the sons of the emperor Theodosius. But the fact seems to be that alterations and additions were made to the Itinerary, and that occasionally, or perhaps under each subsequent emperor, new editions of it were published. From the maritime part of this Itinerary of Antoninus we derive a clear idea of the timidity or want of skill and enterprise of the Mediterranean seamen in their commercial voyages. All the ports which it was prudent or necessary, for the safety of the voyage, to touch at, in sailing from Achaia to Africa are enumerated; and of these there are no fewer than twenty, some of them at the heads of bays on the coasts of Greece, Epirus, and Italy, and within the Straits of Sicily as far as Messina. Their course was then to be directed along the east and south coasts of Sicily to the west point of it; from an island off this point they took their departure for the coast of Africa, a distance of about ninety miles. These Itineraries undoubtedly were drawn up in as accurate a manner as possible; but till the time of Ptolemy they were of little service to geography or commerce, as, for a private individual to have one in his possession was deemed a crime little short of high treason. Geography as a science, therefore, had hitherto made little advances; indeed the discovery and example of Hipparchus, of reducing it to astronomical basis, seems to have been forgotten or neglected till the middle of the second century. The first after him, who attempted to fix geography on the base of science was Marinus, of Tyre, who lived a short time before Ptolemy; of his work we have only extracts given by this geographer. He divided the terms latitude and longitude, which, as we have already stated, were introduced by Artemidorus (A.C. 104) into degrees, and these degrees into their parts, though this improvement was not reduced generally to practice before Ptolemy, for we are informed by him, that Marinus had the latitude of some places and the longitude of others, but scarcely one position where he could ascertain both. With regard to the extent of Marinus' geographical knowledge, or the accuracy of his details, we cannot form a fair judgment from the fragments of his works which remain. According to Ptolemy, he had examined the history of preceding ages, and all the information that had been collected in his own time, comparing and rectifying them as he proceeded in his own account.