The harbour of Aden, then, lies on the south coast of Yemen, as nearly as possible in 12º 45' N. latitude, and 45º 10' E. longitude; somewhat more than 100 miles east of Cape Bab-el-Mandeb, at the entrance of the Red Sea; and about 150 miles by sea, or 120 by land, from Mokha, [34] the nearest port within the Straits. The town was built on the eastern side of a high rocky peninsula, about four miles in length from E. to W., by two miles and a half N. and S.--which was probably, at no very remote period, an island, but is now joined to the mainland by a long low sandy isthmus, [35] on each side of which, to the east and west, a harbour is formed between the peninsula and the mainland. The East Bay, immediately opposite the town, though of comparatively small extent, is protected by the rocky islet of Seerah, rising seaward to the height of from 400 to 600 feet, and affords excellent anchorage at all times, except during the north-east monsoon: but the Western or Black Bay, completely landlocked and sheltered in great part of its extent by the high ground of its peninsula, (which rises to an elevation of nearly 1800 feet,) runs up inland a distance of seven miles from the headland of Jibel-Hassan, (which protects its mouth on the west,) to the junction of the isthmus with the main, and presents at all times a secure and magnificent harbour, four miles wide at the entrance, and perfectly free from rocks, shoals, and all impediments to ingress or egress. Such are the natural advantages of Aden: and "whoever"--says Wellsted--"might have been the founder, the site was happily selected, and well calculated by its imposing appearance not only to display the splendour of its edifices, but also, uniting strength with ornament, to sustain the character which it subsequently bore, as the port and bulwark of Arabia Felix." [Footnote 35: This isthmus is said by Lieutenant Wellsted to be "about 200 yards in breadth:" perhaps a misprint for 1200, as a writer in the _United Service Journal_, May 1840, calls it 1350 yards; and, according to the plan in the papers laid before Parliament, it would appear to be rather more than half a mile at the narrowest part, where it is crossed by the Turkish wall.]