Friedrieh Heinrich Alexander Von Humboldt, baron, a German naturalist, born in Berlin, Sept. 14, 1769, died there, May 6, 1859. He was less than ten years old at the death of his father, who had been adjutant of Duke Ferdinand of Brunswick in the seven years' war, and afterward a Prussian royal councillor. He and his elder brother Wilhelm were educated at home, with special care in the natural sciences. In 1787 he studied at the university of Frankfort-on-the-Oder, returned to Berlin in the following year, and applied himself to the technology of manufactures and to the Greek language. An acquaintance with the botanist Willdenow led him to study the cryp-togamous plants and the family of grasses. He passed a year (1789-90) at the university of Gottingen, studying philology under Heyne, and extending his knowledge of natural history under the guidance of Blumenbach, Lichten-berg, and others. His first published work, the fruit of an excursion from the university, was Ueber die Basalte am Rhein, nebst Unter-svchungen uber Syenit und Basanit der Alten (Berlin, 1790). A rapid journey which he made in 1790, in company with George Forster, through the Low Countries, England, and France, gave him a desire to visit the tropics.

He returned to Germany with the purpose of devoting himself to finance, and repaired to a mercantile academy at Hamburg, where he learned bookkeeping, familiarized himself with counting-house affairs, and practised the modern languages. On a visit to his mother in the following year he obtained permission to engage in practical mining; and he went to the mining academy at Freiberg, where for eight months he enjoyed the private instruction of Werner and the friendship of Freiesleben, Von Buch, and Del Rio, the last of whom 12 years later he found settled in Mexico. He wrote while there a description of the subterranean flora and an account of his experiments on the color of plants withdrawn from the light and surrounded by irrespirable gases, entitled Flora Subterranea Fribergensis, et Aphorismi ex Pliysiologia Chemica Planta-rum, which first appeared in 1793. With Freiesleben he made the first geognostic description of one of the Bohemian mountain ranges. In 1792 he was appointed assessor in the mining department, and subsequently became superior mining officer in the Fichtelgebirge. In 1793-'4 he explored the mining districts in Upper Bavaria, Galicia, and various parts of Prussia. In 1794 he accompanied the minister Hardenberg to Frankfort, and was employed in his cabinet correspondence.

On his return he experimented on the nature of fire-damp in mines. In 1795 he made a geognostic journey through Tyrol, Lombardy, and Switzerland. In 1796 he was sent on a mission to the headquarters of Gen. Moreau in Swabia. From the time when he first heard of Gal-vani's discovery he had accumulated materials for his work Ueber die gereizte Muskel- und Nervenfaser, nebst Vermuthungen fiber den chemischen Process des Lebens in der Thier-und Pflanzenwelt (2 vols., Berlin, 1797-9). He also familiarized himself with practical astronomy, especially with the use of the sextant for determining geographical positions. On the death of his mother he resolved to prosecute his purpose of a great scientific expedition. Leaving Baireuth in 1797, he passed three months at Jena, and then began a second journey to Italy, with a desire to see the volcanoes Vesuvius, Stromboli, and Etna. The disturbed condition of Italy made his purpose impracticable, and he passed the winter in Salzburg and Berchtesgaden, occupied with meteorological observations.

There he accepted the invitation of Lord Bristol to accompany him on an excursion to Upper Egypt, intending also to proceed to Syria and Palestine. He visited Paris to procure the requisite scientific instruments, but in May, 1798, he learned that Lord Bristol had been arrested at Milan charged with having secret political designs in Egypt. Remaining in Paris, he became intimate with the future companion of his travels, the young botanist Bonpland. At this time the public were interested in the voyage of circumnavigation which the directory had decreed and put under the command of Capt. Baudin. The expedition was to explore the E. and W. coasts of South America from Buenos Ayres to Panama, to touch at many islands of the South sea, New Zealand, and Madagascar, and to return by the cape of Good Hope. Humboldt received permission to join the expedition, and to leave it when and where he wished. After several months of suspense, the necessities of war obliged the government to postpone the undertaking.

Thus disappointed in his hopes of travel, Humboldt accepted an invitation to accompany the Swedish consul Skjoldebrand, who had been appointed to carry presents to the dey of Algiers, and he intended to proceed by way of Tunis to Egypt. The delay of the Swedish frigate, and the news from Barbary that during the war bet ween, the Turks and French every person arriving from a French port was thrown into prison, thwarted this purpose. He therefore, in company with Bon-pland, resolved to spend the winter in Spain; and passing through Perpignan, Barcelona, Montserrat, and Valencia, making botanical, astronomical, and magnetic observations by the way, they reached Madrid in February, 1799. He was received with distinguished favor, and the Saxon minister at Madrid, Baron Forell, having overcome the scruples of the Spanish government and procured for him an interview with King Charles IV., all the Spanish possessions in Europe, America, and the East Indies were opened to him, with free permission to use all instruments for astronomical and geodetic observations, the measurement of mountains, the collection of objects of natural history, and investigations of every kind that might lead to the advancement of science. Such extensive privileges had never before been granted to any traveller.

He left Madrid, measuring the elevations on his way through Old Castile, Leon, and Galicia, and on June 5, 1799, embarked with Bonpland in the frigate Pizarro from Corunna. Avoiding the English cruisers, they reached Tene-riffe on June 19, where they tarried to ascend the peak and to make many observations on the natural features of the island, and arrived at Cumana, in Venezuela, July 16, 1799. After exploring the Venezuelan provinces for 18 months, residing the latter part of the time at Caracas, they set out for the interior from Puerto Cabello over the grassy plains of Cala-bozo to the river Apure, a branch of the Orinoco. In Indian canoes they made their way to the most southern post of the Spaniards, Fort San Carlos, on the Rio Negro, within two degrees of the equator. They could have advanced only by taking their boats over land, and therefore returned through the Cassiquiare to the Orinoco, which they followed to Angostura, proceeding thence to Cumana. This journey through wild and unfrequented regions was the first which furnished any positive knowledge of the long disputed bifurcation of the Orinoco. They sailed to Havana, but after a few months hastened to seek some southern port, hearing a false report that Bau-din, whom they had promised to join, had appeared on the W. coast of South America. They embarked in March, 1801, from Batabano, on the S. coast of Cuba. The season of the year forbade the execution of their plan of going to Cartagena and Panama, and they sailed for 54 days up the river Magdalena to Honda, in order to reach the high plateau of Bogota. Thence they made excursions to the most remarkable natural features of the surrounding country.

In September, 1801, in spite of the rainy season, they began to journey southward, passed Ibagua, the Cordillera de Quindiu (at an altitude of 12,000 ft., their highest encampment by night), Cartago, Po-payan, Almaguer, and the lofty plain of Los Pastos, and reached Quito, after experiencing the greatest difficulties for four months, Jan. 6, 1802. The next five months they passed in investigations of the elevated vale of Quito, and of the snow-capped volcanoes which surround it, ascending some of these to heights not before attained. On Chimborazo they reached (June 23, 1802) the altitude of 19,286 ft., about 3,500 ft. higher than the point reached by La Condamine on the Corazon in 1738, and they were prevented only by a deep crevasse from advancing to the summit. They were joined at Quito by a young scholar, Carlos Montufar, son of the marquis of Selvalegre, who attended them throughout their wanderings in Peru and Mexico and back to Paris. Over the pass of the Andes in the paramo of Asuay, by Cuenca and Loja, they descended into the vale of the upper Amazon at Jaen de Bracamoras, and traversing the plateau of Ca-jamarca, by the mountain city Micuipampa (upward of 11,000 ft. high, near the silver mines of Chota), they reached the western declivity of the Peruvian Andes. From the summit of Guangamarca (about 9,500 ft. high) they enjoyed for the first time the long-sought view of the Pacific. They reached the coast at Tru-jillo,and travelled through the sandy deserts of Lower Peru to Lima. After one of the principal designs of their Peruvian journey, the observation of the transit of Mercury over the sun, was fulfilled, they embarked from Callao in December, 1802, and reached Acapulco in Mexico, March 23, 1803. They arrived in the city of Mexico in April, remained there a few months, and then visited Guanajuato and Valladolid, the province of Michoacan near the Pacific coast, and the volcano of Jorullo, which had first broken out in 1759, and returned by way of Toluca to the capital, where they remained long enough to arrange their rich collections and to reduce their various observations to order.

In January, 1804, after having measured the volcano of Toluca and the Cofre de Perote, they descended through the oak forests of Jalapa to Vera Cruz, where they escaped from the then prevalent yellow fever. They compared their barometric measurement of the eastern declivity of the highland of Mexico with that which they had formerly completed of the western declivity, and made a profile of the country from sea to sea, the first that was ever given of any entire country. On March 7, 1804, Humboldt sailed from the coast of Mexico for Havana, where during a two months' residence he completed the materials for his Es8ai politique sur l'ile de Cuba (Paris, 1826). He embarked thence with Bonpland and Montufar for Philadelphia, enjoyed a friendly reception at Washington from President Jefferson, and leaving the new world landed at Bordeaux, Aug. 3, 1804, having spent five years in America, and gained a larger store of observations and collections in all departments of natural science, in geography, statistics, and ethnography, than all previous travellers. He selected Paris for his residence, and remained there till March, 1805, arranging his numerous collections and manuscripts, and experimenting with Gay-Lussac in the laboratory of the polytechnic school on the chemical elements of the atmosphere.

He was accompanied by Gay-Lussac in a visit to Rome and Naples, and also by Von Buch on his return through Switzerland to Berlin, where, after an absence of nine years, he arrived Nov. 16, 1805. In the hope of modifying the ignominious treaty of Tilsit by negotiation, the government resolved in 1808 to send the young brother of the king, Prince "William of Prussia, to the emperor Napoleon at Paris. During the French occupation of Berlin Humboldt had been busy in his garden, making hourly observations of the magnetic declination, and he now received the command of the king to accompany Prince William on his mission. As the condition of Germany made it impracticable to publish there his large scientific works, he was permitted by Frederick William III., as one of the eight foreign members of the French academy of sciences, to remain in Paris, which was his residence, excepting brief periods of absence, from 1808 to 1827. There appeared his Voyage aux regions equinoxiales du nouveau monde (3 vols, fol., with an atlas, Paris, 1809-25; translated into German, 6 vols., Stuttgart, 1825-'32). When in 1810 his elder brother resigned the direction of educational affairs in Prussia to become ambassador at Vienna, the former post was urged upon Alexander von Humboldt; but he declined it, as the publication of his astronomical, zoological, and botanical works was not yet far advanced.

He had also already decided upon a second scientific expedition through upper India, the region of the Himalaya, and Thibet, in preparation for which he was diligently learning the Persian language. He accepted from Count Rumiantzeff in 1812 an invitation to accompany a Russian expedition over Kashgar and Yarkand to the highlands of Thibet, but the outbreak of war between Russia and France caused the abandonment of the plan. The political events between the peace of Paris and the congress of Aix-la-Chapelle gave him occasion for several excursions. He went to England in the suite of the king of Prussia in 1814, again in company with Arago when his brother Wilhelm was appointed ambassador to London, and again in 1818 with Valenciennes from Paris to London and from London to Aix-la-Chapelle, where the king and Hardenberg wished to have him near them during the congress. He also accompanied the king to the congress of Verona and thence to Rome and Naples, and in 1827, at the solicitation of the monarch, gave up his residence in Paris, and returned by way of London and Hamburg to Berlin, where in the following winter he delivered public lectures on the cosmos. In 1829 began a new era in his active career.

He undertook, under the patronage of the czar Nicholas, an expedition to northern Asia, the Chinese Dzungaria, and the Caspian sea, which was magnificently fitted out by the influence of the minister, Count Cancrin. The exploration of mines of gold and platinum, the discovery of diamonds outside of the tropics, astronomical and magnetic observations, and geognostic and botanical collections, were the principal results of this undertaking, in which Humboldt was accompanied by Ehrenberg and Gustav Rose. Their course lay through Moscow, Kazan, and the ruins of old Bulgari to Yekaterinburg, the gold mines of the Ural, the platinum mines at Nizhni Tagilsk, Bogoslovsk, Verkhoturye, and Tobolsk, to Barnaul, Schlangenberg, and Ustkamengorsk in the Altai region, and thence to the Chinese frontier. From the snow-covered Altai mountains the travellers turned toward the southern part of the Ural range, and, attended by a body of armed Cossacks, traversed the great steppe of Ishim, passed through Petropavlovsk, Omsk, Miyask, the salt lake of Ilmen, Zlatusk, Taganai, Orenburg, Uralsk (the principal seat of the Uralian Cossacks), Saratov, Dubovka, Tzaritzyn, and the Moravian settlement Sarepta, to Astrakhan and the Caspian sea.

They visited the Calmuck chieftain Sered Jab, and returned by Voronezh, Tula, and Moscow. The entire journey of over 10,-000 miles was made in nine months; its results are given in Rose's Mineralogisch-geognostische Reise nach dem Ural, Altai und dem Kaspischen Meere (2 vols., Berlin, 1837-42), and in Humboldt's Asie centrale, reclierches sur les chaines de montagnes et la climatologie comparee (3 vols., Paris, 1843; translated into German by Mahlmann, 2 vols., Berlin, 1843-'4). This expedition extended the knowledge of telluric magnetism, since in consequence of it the Russian imperial academy established a series of magnetic and meteorological stations from St. Petersburg to Peking, an example which was followed by the British government in the southern hemisphere. The convulsions of 1830 gave a more political direction to Humboldt's activity for several years, without interrupting his scientific career. He had accompanied the crown prince of Prussia in May, 1830, to Warsaw, to the last constitutional diet opened by the emperor Nicholas in person, and he attended the king to the baths of Teplitz. On the news of the French revolution 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 nouveau 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 resided in Paris several months in 1847-8, from which time he lived in Prussia, usually in Berlin, pursuing his scientific labors in his advanced age with undiminished zeal and energy. - 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 elevations, 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. Linnaeus and some of his successors had observed some of the more palpable phenomena of the migrations of plants, without, however, considering elevation or temperature. It remained for Humboldt to bring together the vast series of facts collected from the most remote points, to combine 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 distribution is connected with the temperature of the air, as well as with the altitudes of the surface on which they grow, and he systematized his researches into a general exposition of the laws by which the distribution of plants is regulated.

Connected with this subject he made 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 associating many important questions with botany, he made it one of the most attractive of the natural sciences. He showed the powerful 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 between 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 phraseology, his works are marked by poetical conceptions of nature wherever it is his aim to present broad and complete pictures. His delineations 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 Teneriffe, Chimborazo, and numerous other mountains, and made 459 measurements of altitude, which were often confirmed by trigonometrical 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 animals. 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 continents 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: Physique generate et geologie (Paris, 1807); Essai geognostique sur le gisement des roches 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 Distributione Geographi-ca Plantarum secundum Cozli Temperiem et Altitudinem Montium (1817). The rich herbarium collected by him and Bonpland contained more than 5,000 species of phanerogamous plants, of which 3,500 were new. They were arranged and illustrated by Humboldt, Bonpland, and Kunth, in the following works, which form the sixth part of his "Travels:" Plantes equinoxiales, recueillies au Mexique, dans l'ile de Cuba, etc. (2 vols., 1809 et seq., with 144 plates); Monographic des melastomes et autre8 genres du meme ordre (2 vols., 1809-'23, with 120 colored plates); Nova Genera et Species Plantarum, etc. (7 vols., 1815-25, with 700 plates); Mimoses et autres plantes legumineu-ses du nouveau continent (1819-'24, with 60 plates); Synopsis Plantarum, etc. (4 vols., 1822-'6); Revision des graminees (2 vols., 1829-'34, with 220 colored plates). The zoological results of his travels are contained in his Recueil d" observations de zoologie et d'ana-tomie comparee (2 vols., 1805-32), in the publication of which he was aided by Cuvier, Latreille, and Valenciennes. Another costly work, the Vues des Cordilleres et monuments des peuples indigenes de l'Amerique (1810, with 69 plates), contains elaborate pictures of the scenery of the Andes and of the monuments of the ancient civilization of the aborigines.

The study of the great architectural works of the ancient Mexicans and Peruvians led Humboldt to investigations of their languages, records, early culture, and migrations. In this department his treatment was peculiar, for his Essai politique sur le royaume de la Nouvelle Espagne (2 vols., 1811) contained statistics united with the facts of natural history, and presented various doctrines of political economy from a new point of view. Especially original and influential were his reflections on the culture of the soil under different climates and on its effects upon civilization, and on the circulation of the precious metals. Besides his general works, he made many special investigations, as his treatise on the geography of the middle ages, in which he appears at once as historian, astronomer, and savant, his chemical labors with Gay-Lussac, his system of isothermal lines, his experiments on the gymnotus and on the respiration of fishes, and numerous contributions to physical geography. Soon after his return from America he gave a general sketch of the results of his inquiries in his Ansichten der Natur (Stuttgart, 1808), in which he aimed to present a picture of the physical world, exclusive of everything that relates to the turmoil of human society and the ambitions of individual men; and in the evening of his life he determined to give a systematic view of the results of his investigation and thought in the whole domain of natural science.

This was the design of his Kosmos (5 vols, Stuttgart, 1845-'62), which explains the physical universe according to its dependencies and relations, grasps nature as a whole moved and animated by internal forces, and by a comprehensive description shows the unity which prevails amid its variety. He lived to complete this work, but the last volume was published after his death. It was translated into almost all the European languages, and has been without an equal in giving an impulse to natural studies. To his personal influence is due nearly all that the Prussian government did for science in the latter part of his life. Agassiz says of him: "The personal influence he exerted upon science is incalculable. With him ends a great period in the history of science; a period to which Cuvier, Laplace, Arago, Gay-Lussac, De Candolle, and Robert Brown belonged." His personal habits were peculiar. He slept but four hours, rose at 6 in the winter and 5 in the summer, studied two hours, drank a cup of coffee, and returned to his study to answer letters, of which he received hundreds every day. From 12 to 2 he received visits, and then returned to study till the dinner hour.

From 4 till 11 he passed at the table, generally in company with the king, but sometimes at the meeting of learned societies or in the company of friends. At 11 he retired to his study, and his best books are said to have been written at midnight. Many of the works of Humboldt are now almost inaccessible on account of their great cost. A new edition of his select works was published in Stuttgart in 1874, in 36 numbers, including Kosmos, with a biographical sketch by Bernhard von Cotta; Ansichten der Natur, with scientific explanations; and Reise in die Aequinoctialgegenden des neuen Continents, by Hermann Hauff, the only authorized German translation of this work. English translations of his "Travels," "Views of Nature," and "Kosmos" are contained in Bonn's "Scientific Library," of which they constitute nine volumes. The translation of "Kosmos" has been republished in New York in 5 vols. 12mo. The centenary of Humboldt's birth, Sept. 14, 1869, was celebrated in Germany and the United States, and eulogies were pronounced by many of the foremost scientific men of the day, among whom were Bastian, Dove, Ehrenberg, Virchow, and Agassiz. Many biographies of him have been published, the best being Alexander von Humboldt, eine wissenschaftliche Biographie, edited by Karl Bruhns, a joint production of Ave-Lallemant, Carus, A. and H. W. Dove, Ewald, Grisebach, Lowenberg, Peschel, Wiedemann, Wandt, and the editor, aided by the friends and relatives of Humboldt, and by the Prussian government (3 vols., Leipsic, 1872; English translation by Jane and Caroline Lassells, "Life of Alexander von Humboldt," 2 vols., London, 1872). See also his Briefe an Varnhagen von Ense aus den Jahren 1827-'58, published by Ludmille Assing, with extracts from Varnhagen's diaries (Leipsic, 1860); and Les barons de Forell, by Alexandre Daguet (Lausanne, 1873), containing many letters of Humboldt and an interesting account of his negotiations in 'Madrid for the exploration of the Spanish possessions in both hemispheres.