The isthmus connecting Attica with the Peloponnesus is not level. The roots of the Onean Mountains are continued along the eastern coast in a line of low cliffs, till they meet another range, which seems to have borne the same name, at the opposite extremity of the isthmus. This is an important feature in the face of the country: the isthmus at its narrowest part, between the inlets of Schœnus and Lechæum, is only between three and four miles broad; and along this line, hence called the Diolcus, or Draughtway, vessels were often transported from sea to sea, to avoid the delay and danger which attended the circumnavigation of the Peloponnesus. Yet it seems not to have been before the Macedonian period, that the narrowness of the intervening space suggested the project of uniting the two seas by means of a canal. It was entertained for a time by Demetrius Poliorcetes; but he is said to have been deterred by the reports of his engineers, who were persuaded that the surface of the Corinthian Gulf was so much higher than the Saronic, that a channel cut between them would be useless from the rapidity of the current, and might even endanger the safety of Ægina and the neighbouring isles. Three centuries later, the dictator Cæsar formed the same plan, and was perhaps only prevented from accomplishing it by his untimely death. The above-mentioned inequality of the ground would always render this undertaking very laborious and expensive. But the work was of a nature rather to shock than to interest genuine Greek feelings: it seems to have been viewed as an audacious Titanian effort of barbarian power; and when Nero actually began it, having opened the trench with his own hands, the belief of the country people may probably have concurred with the aversion of the Prætorian workmen, to raise the rumour of howling spectres, and springs of blood, by which they are said to have been interrupted. The face of the Peloponnesus presents outlines somewhat more intricate than those of northern Greece. At first sight the whole land appears one pile of mountains, which, toward the northwest, where it reaches its greatest height, forms a compact mass, pressing close upon the Gulf of Corinth. On the western coast it recedes farther from the sea; towards the centre is pierced more and more by little hollows; and on the south and east is broken by three great gulfs, and the valleys opening into them, which suggested to the ancients the form of a plane leaf, to illustrate that of the peninsula. On closer inspection, the highest summits of this pile, with their connecting ridges, may be observed to form an irregular ring, which separates the central region, Arcadia, from the rest.