Now let us go on our journey. We are traversing the ocean in a mail steamer; we leave Colombo or Bombay or Karachi and steam westward into the Gulf of Aden. Here we have one of the most remarkable contrasts of climate to be found in the world. In Ceylon or at Bombay rain and heat combine to produce a luxuriant tropical vegetation capable of supporting much human and animal life. There are other countries--and we are going to traverse some of them--which although hot enough, have little rain. Let us realise this contrast; for in taking a voyage from Colombo or Bombay to Aden we go from a well watered country to one which lacks water. Here is a scene in Ceylon, showing the rank vegetation which results from tropical heat and monsoon rains. Here, on the other hand, is the British fortress of Aden. It rains on an average in Aden only once in several years, but when it does rain it rains very hard, and these great tanks were constructed to gather the water from the naked rocky slopes around, and to store it for use in the next few years. You see that two or three shrubs are grown as curiosities beside the tank. But as Aden grew into a populous settlement the tanks were not sufficient for the wants of the people. The British distil fresh water from the sea. [Sidenote: 30. Bumboats at Aden.] Aden is a British fortress. It is not an island, but it is the next thing to an island--it is a peninsula. It is therefore easily defended by warships on the sea. The narrow isthmus connecting it to the mainland has been fortified. [Sidenote: 31. Routes from India to Suez.] [Sidenote: 32. The Suez Canal.] So we pursue our journey until we come to Suez. This map shows you the routes from India across the Western Indian Ocean and up the Gulf of Aden and the Red Sea to Suez, at the entrance to the Suez Canal. On the right hand we see Mecca marked in the map. Peace on the ocean, the traffic of steamships, and the British station at Aden have rendered the Haj less expensive than it used to be and less dangerous, so that many more Mohammedans now go to Mecca from India. Next we see our steamer in the Suez Canal. The banks are brown and desert, for a shower of rain is very rare, and the whole isthmus is naked rock and sand. The sea way is now continuous from the Red Sea. But the making of the Canal would have been impossible unless there had been fresh water near at hand in Egypt for the nourishment of the workers. The army of workmen who dug the Canal were supplied with sweet water by means of a small canal from the Nile. So you see that the Suez Canal was possible only because of the great river of Egypt, which brings water through the desert from far off sources. [Sidenote: 33. Map of Lower Egypt.]