The heat was extreme, and great salt-plains, where no watercourses exist, had to be crossed. Upon the 6th of April, Seetzen arrived in Bethlehem, and soon afterwards at Jerusalem, having suffered greatly from thirst, but having passed through most interesting countries, hitherto unvisited by any modern traveller. [Illustration: Jerusalem.] [Illustration: Map of Egypt, Nubia, and part of Arabia.] He had also collected much valuable information respecting the nature of the waters of the Dead Sea, refuted many false notions, corrected mistakes upon the most carefully constructed maps, identified several sites of the ancient Peraea, and established the existence of numberless ruins, which bore witness to the prosperity of all this region under the sway of the Roman Empire. Upon the 25th of June, 1806, Seetzen left Jerusalem, and returned to St. Jean d'Acre by sea. In an article in the _Revue Germanique_ for 1858, M. Vinen speaks of his expedition as a veritable journey of discovery. Seetzen, however, was unwilling to leave his discoveries incomplete. Ten months later, he again visited the Dead Sea, and added largely to his observations. From thence he proceeded to Cairo, where he remained for two years, and bought a large portion of the oriental manuscripts which now enrich the library of Gotha. He collected many facts about the interior of the country, choosing instinctively those only which could be amply substantiated. Seetzen, with his insatiable thirst for discovery, could not remain long in repose, far removed from idleness though it was. In April, 1809, he finally left the capital of Egypt, and directed his course towards Suez and the peninsula of Sinai, which he resolved to explore before proceeding to Arabia. At this time Arabia was a little-known country, frequented only by merchants trading in Mocha coffee-beans. Before Niebuhr's time no scientific expedition for the study of the geography of the country or the manners and customs of the inhabitants had been organized. This expedition owed its formation to Professor Michalis, who was anxious to obtain information which would throw light on certain passages in the Bible, and its expenses were defrayed by the generosity of King Frederick V. of Denmark. It comprised Von Hannen, the mathematician, Forskaal, the naturalist, a physician named Cramer, Braurenfeind, the painter, and Niebuhr, the engineer, a company of learned and scientific men, who thoroughly fulfilled all expectations founded upon their reputations. In the course of two years, from 1762 to 1764, they visited Egypt, Mount Sinai, Jeddah, landed at Loheia, and advancing into Arabia Felix, explored the country in accordance with the speciality of each man. But the enterprising travellers succumbed to illness and fatigue, and Niebuhr alone survived to utilize the observations made by himself and his companions. His work on the subject is an inexhaustible treasury, which may be drawn upon in our own day with advantage.