34 [338] 



DARWIN AND HUMBOLDT. 



had mainly consisted in maps and the 

 delineation of the characteristic plants 

 and animals. Humboldt devised a 

 new method, equally impressive to 

 the eye and comprehensive in its out- 

 lines. Impressed by the fact that 

 vegetation changes its character as it 

 ascends upon the side of high mount- 

 ains, — thus presenting successive ter- 

 races upon their slopes, — he conceived 

 the idea, already suggested by his ex- 

 amination of the Peak of Teneriffe, of 

 drawing upon the outline of a conical 

 mountain the different aspects of its 

 surface from the level of the sea to 

 its highest peak. Thus he could ex- 

 hibit at a glance all the successive 

 zones of vegetation. Afterward he 

 extended these comparisons to the 

 temperate and arctic zones, and 

 ascertained that, as we proceed 

 further north, the gradation of the 

 vegetation, at the level of the ocean, 

 corresponds to its succession upon 

 mountain slopes, — until, toward the 

 Arctics, it assumes a remarkable 

 resemblance to the plants found near 

 the line of perpetual snows under the 

 Tropics. But this is not all. The 

 intervening expanse from North to 

 South, as far as the equator, and then 

 in reverse order to the Antarctic 

 regions, also exhibits, in proportion to 

 the elevation of the land, a vegetation 

 characterized by intermediate forms. 



In the same way he reproduced the 

 general appearance of the inequalities 

 of the earth's surface by drawing ideal 

 sections across the regions described. 

 In the first place, through Spain, af- 

 terward from La Guayra to Caraccas 

 across the Cunibre, from Cartagena 

 to Santa Fe de Bogota, and finally 

 through the whole continent of 

 America, from Acapulco to Vera 

 Cruz. And this not by mere ap- 

 proximations, but founding his pro- 

 files upon his own barometric and 

 astronomical observations, which he 

 multiplied to such an extent that his 

 works are to this day the chief source 

 of information concerning the physical 

 geography of the regions visited by 

 him. 



Not satisfied with this, he under- 



took to represent, in like manner, the 

 internal structure of the earth, draw- 

 ing similar charts upon which the 

 relative position of the rocks, with 

 signs to indicate their mineralogical 

 character, is faithfully portrayed. The 

 first chart of this kind was drawn by 

 him in Mexico in 1804, and presented 

 to the School of Mines of that city. 

 It was afterward published in the 

 Atlas of the American Journey. — We 

 are thus indebted to him for the 

 whole of that graphic method which 

 has made it possible to delineate, in 

 visible outlines, the true characterist- 

 ics of physical phenomena ; for after- 

 ward this method was applied to the 

 representation of the oceanic currents, 

 the direction of the prevalent winds, 

 the tidal waves, the rise and fall of 

 our lakes and rivers, the amount of 

 rain falling upon different parts of the 

 earth's surface, the magnetic phenom- 

 ena, the lines of equal average tem- 

 perature, the relative height of our 

 plains, table-lands and mountain 

 chains, their internal structure, and 

 the distribution of plants and animals. 

 Even the characteristic features of 

 the History of Mankind are now 

 tabulated in the same way upon our 

 ethnographical maps, in which the 

 distribution of the races, the high- 

 ways of navigation and commerce, 

 the difference among men as to lan- 

 guage, culture, creeds, nay, even the 

 records of our census, the estimates of 

 the wealth of nations, down to the 

 statistics of agriculture and the aver- 

 ages of virtue and vice, are represent- 

 ed. In short, every branch of mental 

 activity has been vivified by this 

 process, and has undergone an entire 

 transformation under its influence. 



His paper upon the isothermal lines 

 was published in the " Memo ires de 

 la Societe cPArcu-eil" a scientific 

 club to which, in the beginning of 

 this century, the most eminent men 

 of the age belonged. Though a mere 

 sketch, the first delineation of the 

 curves uniting different points of the 

 earth's surface which possess the 

 same average annual temperature un- 

 der varying latitudes, exhibits already 



