and have wants that are similar: for a commerce among themselves, therefore, they lack the main elements, viz., difference of production, and the diversity of wants which are the consequence of variety of climates. To reach these, the Mediterranean people have had to encounter the tedious navigation and the sometimes difficult egress—just described—from their sea. Clearing the Straits of Gibraltar, their vessels do not even then find themselves in a position so favourable for reaching the markets of the world as they would be were they in Liverpool or off the Lizard. Such is the obstruction which the winds and the current from the Atlantic offer to the navigation there, that vessels bound to Lidia from the United States, England, or Holland, may often double the Cape of Good Hope before one sailing with a like destination from a Mediterranean port would find herself clear of the Straits of Gibraltar. It is therefore not surprising that none of the great commercial marts of the present day are found on the shores of this classic sea. The people who inhabit the hydrographic basin of the Mediterranean—which includes the finest parts of Europe—have, ever since the discovery of the passage around the Cape of Good Hope, been commercially pent up. A ship-canal across the Isthmus of Suez will let them out into the commercial world, and place them within a few days of all the climates, wants, supplies, and productions of India. It will add largely to their wealth and prosperity. As these are increased, trading intercourse is enhanced, and so by virtue of this canal they will become better customers for England and Holland, and all other trading nations whose ports are havens of the Atlantic. Occupying this stand-point in their system of commercial economy, the people of the United States await with a lively interest the completion of the Suez Canal.
380. Hydrometrical observations at sea wanted.—Of all parts of the ocean, the warmest water, the saltest and the heaviest too, is said to be found in the seas of the Indian Ocean. A good .series of observations there -with the hydrometer, at the different seasons of the year, is a desideratum. Taking, however, such as we have upon the density of the water in the Red Sea and the Mediterranean, and upon the under currents that run out from these seas, let us examine results.
381. Specific gravity of Red Sea water.—Several years ago, Mr. Morris, chief engineer of the Oriental Company's steam-ship Ajdaha, collected specimens of Red Sea water all the way from
