Upon the 21st of April, 1815, Burckhardt joined a caravan which conducted him to Yembo, where the plague was raging. The traveller at once fell ill and became so weak that it was impossible for him to resort to a country place. To embark was equally impossible; all the vessels which were ready to start were crowded with soldiers. He was compelled to remain eighteen days in the unhealthy little town, before he could obtain a passage in a small vessel which took him to Cosseir, and thence to Egypt. Upon his return to Cairo Burckhardt heard of his father's death. The traveller's constitution had been sorely tried by illness, and he was unable to attempt the ascent of Mount Sinai until 1816. The study of natural history, the publication of his diary, and his correspondence, occupied him until 1817, at which time he expected to go with a caravan to Fezzan. Unfortunately he succumbed to a sudden attack of fever, his last words being, "Write and tell my mother that my last thought was of her." Burckhardt was an accomplished traveller; well-informed, exact to minuteness, patient, courageous, and endowed with an upright and energetic character. His writings are of great value; the narrative of his voyage in Arabia--of which he unfortunately could not explore the interior--is so complete and precise, that owing to it that country was then better known than many in Europe. In writing to his father from Cairo on the 13th of March, 1817, he says, "I have never said a word about what I have seen and met with that my conscience did not entirely justify; I did not expose myself to so much danger in order to write a romance!" The explorers who have succeeded him in the same countries unanimously testify to his exactness, and agree in praising his fidelity, knowledge, and sagacity. "Few travellers," says the _Revue Germanique_, "have enjoyed in a like degree the faculty of observation. That is a rare gift of nature, like all eminent qualities. He possessed a sort of intuition which discerned the truth, apart from his own observations, and thus information given by him from hearsay has a value that seldom attaches to statements of that nature. His mind, early ripened by reflection and study (he was but in his thirty-third year at the time of his death), invariably went straight to the point. His narrative, always sober, is filled--one may say--rather with things than words; yet his narratives possess infinite charm; one admires the man in them as much as the savant and observer." While the Biblical countries occupied the attention of Seetzen and Burckhardt, India, the birthplace of most of the European languages, was about to command the attention of students of language, literature, and religion, as well as of geography. For the present our concern is with those problems of physical geography, which the conquests and studies of the India Company were about to solve by degrees.