One of the earliest of the scientific travelers, to whom we have alluded, was John Lewis Burckhardt, who spent several years, in the early part of the present century, in exploring the countries around the southeastern shores of the Mediterranean Sea, under the auspices of a society established in London, called the Association for Promoting the Discovery of the Interior Parts of Africa. Burckhardt prepared himself for his work, by taking up his residence for several years in Aleppo, and in other Oriental cities, for the purpose of studying the Arabic language, and making himself perfectly familiar with the manners and customs of the people, so that in traveling through the countries which he was intending to explore, he might pass for a native, and thus be allowed to go where he pleased without molestation. He succeeded perfectly in attaining this object. He acquired the Arabic language, assumed the Arabic dress, and learned to accommodate himself, in all respects, to the manners and customs of the country. He thus passed without hindrance or suspicion where no known European or Christian would have been allowed to go. [Illustration: THE VALLEY OF ARABAH.] Burckhardt explored the valley of Arabah, which extends from the Dead Sea to the Red Sea, forming, as has already been said, a southern continuation of the great Jordan gorge. He was, in fact, the first to bring the existence of this southern valley to the notice of the civilized world. The valley of the Jordan, as he describes it, widens about Jericho, where the hills which border it, join the chains of mountains which inclose the Dead Sea. At the southern extremity of the sea they again approach each other, leaving between them a valley or Ghor, similar in form to the northern Ghor, through which the Jordan flows; though the southern valley, from want of water, is a desert, while the Jordan and its tributaries make the other a fertile plain. In the southern Ghor, the rivulets which descend from the mountains are lost in the sand and gravel which form their beds, long before they reach the valley below. The valley itself, therefore, is entirely without water, and is, consequently, barren and desolate. The whole plain, as Burckhardt viewed it, presented the appearance of an expanse of shifting sands, the surface varied with innumerable undulations and low hills. A few trees grow here and there in the low places, and at the foot of the rocks which line the valley; but the depth of the sand, and the total want of water in the summer season, preclude the growth of every species of herbage. A few Bedouin tribes encamp in the valley in the winter, when the streams from the mountains being full, a sufficient supply of water is produced to flow down into the valley, causing a few shrubs to grow, on which the sheep and goats can feed.