The passage between them is practicable by small craft only, whose planks are sewed together, and are not affected by a stroke upon hard ground for it is not for want of water that this navigation is dangerous. All the west coast is very bold, and has more depth of water than the east; but on this side there is no anchoring ground, nor shoals. It is a rocky shore, and there is depth of water every where, yet that part is full of sunken rocks; which, though not visible, are near enough the surface to take up a large ship, whose destruction thereupon becomes inevitable. This I presume arises from one cause. The mountains on the side of Egypt and Abyssinia are all (as we have stated) hard stone, Porphyry, Granite, Alabaster, Basaltes, and many sorts of Marble. These are all therefore fixed, and even to the northward of lat 16°, where there is no rain, very small quantities of dust or sand can ever be blown from them into the sea. On the opposite, or Arabian side, the sea-coast of the Hejaz, and that of the Tehama, are all moving lands; and the dry winter-monsoon from the south-east blows a large quantity from the deserts, which is lodged among the rocks on the Arabian side of the Gulf, and confined there by the north-east or summer-monsoon, which is in a contrary direction, and hinders them from coming over, or circulating towards the Egyptian side.
From this it happens, that the west, or Abyssinian side, is full of deep water, interspersed with sunken rocks, unmasked, or uncovered with sand, with which they would otherwise become islands. These are naked and bare all round, and sharp like points of spears; while on the east-side there are rocks, indeed, as in the other, but being between the south- east monsoon, which drives the sand into its coast, and the
