The most extensive and important of these journeys were to Greece and Constantinople, and back through Hungary; to Paris and Southern France; and to England, Sweden, and Norway. He afterward concentrated his whole attention upon geography, giving up for this purpose all employment that was not connected with it. From 1832 the series of volumes on Asia appeared in rapid succession; the nineteenth volume was finished only a few weeks before his death. With the progress of this work, his fame increased from year to year, and his connections and the influence which he exerted upon the progress of geographical research were extended to all the countries of the civilized world. He became one of the most important personal centers in the whole domain of geographical science, not less on account of the incomparable richness of his knowledge than on account of the living interest which he took in all current questions. In this position he did not fail to receive distinctions of every kind. As a teacher he acquired a brilliant clientage. When he published his first lecture on general geography in 1820, it is said that he had not a single scholar; afterward the largest lecture-rooms were not sufficient to hold his classes, and at Berlin it became the fashion to attend his lectures. As a teacher, and in all his personal relations, he possessed a strong attractive influence. Kramer, his biographer, says that no one ever approached him without meeting the most kindly reception, that he was ready to recognize every honestly meant effort, to encourage, to help with counsel and support. No man ever had less of egotism. His physical condition was generally good through the whole of his long life. He had a strong constitution, which was hardened by exercise in his youth and strengthened by the pedestrian excursions taken on his journeys. The weaknesses of age began to appear in his later years, and, on account of them, he often visited the springs of Teplich with good effects. He made a visit to these springs in 1859, the year of his death, but returned no stronger, and died on the 28th of September. After his death were published his "Geschichte der Erdkunde und der Entdeckimgen," 1861; "Allgemeine Erdkunde," 1862; and "Europa," 1863.
