The travellers landed at El Akabah on the Red Sea, and went with a small Arab caravan to El Khalil, the ancient Hebron. The route they followed had never before been trodden by a European. It led through a wide, flat valley terminating at the Dead Sea; a valley through which the waters of the Dead Sea were supposed at one time to have flowed towards the Red Sea. This hypothesis was shared by Burckhardt and many others who had only seen the district from a distance, and who attributed the cessation of the drainage to an upheaval of the soil. The heights, as taken by the travellers, showed this hypothesis to be altogether erroneous.
In fact from the lower end of the Persian Gulf the country presents a continuous ascent for two or three days' march to the point called by the Arabs the Saddle, from thence it begins to sink and slopes down towards the Dead Sea. The Saddle is about 2100 feet above the sea-level, at least that was the estimate given a year later by Count Bertou, a Frenchman, who visited those localities at that time.
On their way down to the Bituminous Lake, Schubert and his companions took some other barometrical observations, and were very much surprised to find their instrument marking ninety-one feet below the Red Sea, the levels gradually decreasing in height as they advanced. At first they thought there must be some mistake, but finally, the evidence was too strong for them, and it became proved beyond a doubt that the Dead Sea could never have emptied its waters into the Red Sea for the very excellent reason that the level of the former is very much lower than that of the latter.
The depression of the Dead Sea is very much more noticeable when Jericho is approached from Jerusalem. In that case the way lies through a long valley with a very rapid slope, all the more remarkable as the hilly plains of Judea, Peræ, and El Harran are very lofty, the latter rising to a height of nearly 3000 feet above the sea-level.
The appearance of the country and the testimony of the instruments were in such contradiction to the prevalent belief, that Messrs. Erdl and Schubert were very unwilling to accept the results obtained, which they attributed to their barometer being out of order and to a sudden disturbance of the atmosphere. But on their way back to Jerusalem the barometer returned to the mean height it had registered before they started for Jericho. There was nothing for it then but to admit, whether they liked it or not, that the Dead Sea was at least 600 feet below the level of the Mediterranean, an estimate, as later researches showed, which fell one-half short of the truth.
This, it will be admitted, was a fortunate rectification, which would have considerable influence, by calling the attention of savants to a phenomenon which was soon to be verified by other explorers.
At the same time, the survey of the basin of the Dead Sea was completed and rectified. In 1838, two American Missionaries, Edward Robinson and Eli Smith, gave quite a new impulse to Biblical geography. They were the forerunners of that phalanx of naturalists, historians, archæologists, and engineers, who, under the patronage or in conjunction with the English Exploration Society, were soon to explore the land of the patriarchs from end to end, making maps of it, and achieving discoveries which threw a new light on the history of the ancient peoples who, by turns, were possessors of this corner of the Mediterranean basin.
But it was not only the Holy Land, so interesting on account of the many associations it has for every Christian, which was the scene of the researches of scholars and explorers; Asia Minor was also soon to yield up her treasures to the curiosity of the learned world. That country was visited by travellers in every direction. Parrot visited Armenia; Dubois de Monpereux traversed the Caucasus in 1839. In 1825 and 1826, Eichwald explored the shores of the Caspian Sea; and lastly, Alexander von Humboldt at the expense of the generous Nicholas, Emperor of Russia, supplemented his intrepid work as a discoverer in the New World by an exploration of Western Asia and the Ural Mountains. Accompanied by the mineralogist Gustave Rose, the naturalist Ehrenberg, well known for his travels in Upper Egypt and Nubia, and Baron von Helmersen, an officer of engineers, Humboldt travelled through Siberia, visited the gold and platinum mines of the Ural Mountains, and explored the Caspian steppes and the Altai chain to the frontiers of China. These learned men divided the work, Humboldt taking astronomical, magnetic, and physical observations, and examining the flora and fauna of the country, while Rose kept the journal of the expedition, which he published in German between 1837 and 1842.
Although the explorers travelled very rapidly, at the rate of no less than 11,500 miles in nine months, the scientific results of their journey were considerable. In a first publication which appeared in Paris in 1838, Humboldt treated only the climatology and geology of Asia, but this fragmentary account was succeeded in 1843 by his great work called "Central Asia." "In this," says La Roquette, "he has laid down and systematized the principal scientific results of his expedition in Asia, and has recorded some ingenious speculation as to the shape of the continents and the configuration of the mountains of Tartary, giving special attention to the vast depression which stretches from the north of Europe to the centre of Asia beyond the Caspian Sea and the Ural River."
We must now leave Asia and pass in review the various expeditions in the New World, which have been sent out in succession since the beginning of the present century. In 1807, when Lewis and Clarke were crossing North America from the United States to the Pacific Ocean, the Government commissioned a young officer, Lieutenant Zabulon Montgomery Pike, to examine the sources of the Mississippi. He was at the same time to endeavour to open friendly relations with any Indians he might meet.