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 44: IIUMBOLDT son, and he attended the king to the baths of Teplitz. On the news of the French revo- lution and the accession of Louis Philippe, he was selected to convey to Paris the Prussian recognition of the new monarch, and to send political advices to Berlin. The latter office fell to him again in 1834-'5, and he was called upon to fulfil it five times in the following twelve years, residing four or five months in Paris on each mission. To this period belongs the publication of his Examen critique de la geographie du nouneau continent (5 vols., Paris, 1835-*8; translated into German by Ideler, 5 vols., Berlin, 1836 et seq.). He made a rapid journey with King Frederick William IV. to England in 1841, to attend the baptism of the prince of Wales, to Denmark in 1845, and re- sided in Paris several months m'1847-'8, from which time he lived in Prussia, usually in Berlin, pursuing his scientific labors in his advanced ago with undiminished zeal and en- ergy. Humboldt was distinguished, as a man of science, for the comprehensiveness of his researches, and especially for the skill and completeness with which he connected his own observations with all the stores of previous knowledge, and for the clearness with which he expounded facts in their relations. This tendency appeared in one of his earliest works on the contraction of the muscles and nerves, in which, after the progress of physiology for more than half a century, may still be seen the sagacity of his experiments on galvanism, and the truth of most of the inferences which he drew. In his travels he measured eleva- tions, and investigated the nature of the soil and the thermometrical relations, at the same time collecting herbariums, and founding, by a combination of the materials in his hands, the new science of the geography of plants. Linnaaus and some of his successors had observed some of the more palpable phenomena of the migra- tions of plants, without, however, considering elevation or temperature. It remained for Hum- boldt to bring together the vast series of facts collected from the most remote points, to com- bine them with his own observations, to show their connection with the laws of physics, and to develop the principles in accordance with which the infinitely numerous forms of the vegetable world have been spread over the earth. He was the first to see that this dis- tribution is connected with the temperature of the air, as well as with the altitudes of the surface on which they grow, and he systema- tized his researches into a general exposition of the laws by which the distribution of plants is regulated. Connected with this subject he iiuule those extensive investigations into the mean temperature of a large number of places on the surface of the globe which led to the drawing of the isothermal lines, so important in their influence in shaping physical geography and giving accuracy and simplicity to the mode of representing natural phenomena. By as- sociating many important questions with bot- any, he made it one of the most attractive of the natural sciences. He showed the pow- erful influence exercised by vegetable nature upon the soil, upon the character of a people, and upon the historical development of the human race. This view of the connection be- tween the physical sciences and human history opened a path which has been followed by a school of subsequent investigators with novel and important results. Though wholly free from mystical meanings and obscure phrase- ology, his works are marked by poetical con- ceptions of nature wherever it is his aim to present broad and complete pictures. His de- lineations of the tropical countries give delight to readers who have no special knowledge of or interest in natural history. At the beginning of this century even the coasts of the immense Spanish colonies in America were scarcely known, and but little confidence was placed in the best maps. More than 700 places of which he made astronomical measurements were calculated anew by Oltmanns, whose work (2 vols., Paris, 1808-'10) forms the fourth part of Humboldt's " Travels." He himself made the map of the Orinoco and the Magdalena, and the greater part of the atlas of Mexico. He travelled with the barometer in his hands from Bogota to Lima, ascended the peaks of Teneriife, Chimborazo, and numerous other mountains, and made 459 measurements of al- titude, which were often confirmed by trigo- nometrical calculations. His measurements in Germany and Siberia, combined with those made by other travellers, furnished valuable results to geography, and were the foundation of theories of the dispersion of plants and ani- mals. Climatology was intimately connected with his researches. By his daily record of the meteorological, thermometrical, and electrical phenomena of the countries through which he passed, he instituted the science of comparative climatology. He was the first to entertain the idea of estimating the average elevation of con- tinents above the sea, previous geographers and geologists having considered only the altitude of mountain chains and of the lower lands. His principal works in this department are : Phy- sique generate et geologic (Paris, 1807); Essai geognostique sur le gisement des rochet dans les deux hemispheres (1823-'6); and Fragments de geologie et climatologie asiatique (2 vols., 1831 ; translated into German by Lowenberg, Berlin, 1832). The phenomena of the volcanoes of South America and Italy he keenly observed and explained. With Bonpland he made very important observations on the sites, uses, and structure of plants. His principal botanical works are Essai sur la geographie des plantes (Paris, 1805), and De Distribution e GeograpTii- ca Plantarum secundum Cceli Temperiem et Altitudinem Montium (1817). The rich her- barium collected by him and Bonpland con- tained more than 5,000 species of phaneroga- mous plants, of which 3,500 were new. They were arranged and illustrated by Humboldt,