ALEXANDER VON HUMBOLDT 359 



decrement of magnetic force from the poles to the equator as the most 

 important result of my American voyage." The subject arrested the 

 attention of the British Association, which made special arrangements 

 for its careful study. While living at Quito, Humboldt gave what he 

 deemed first-hand study to the nature and cause of earthquakes and 

 arrived at conclusions which were strengthened, as he believed, by 

 similar studies in the same region by Bousingault, twenty-three years 

 later. Bousingault's treatise on earthquakes, Humboldt accepted as the 

 best and most authoritative ever written. Its theories will hardly be 

 regarded as final by scientists of our time. Eocks, Humboldt declares, 

 without any qualification are in the process of formation and disinte- 

 gration. He divides them into eruptive, sedimentary, metamorphic and 

 conglomerate rocks. The importance of the subject of paleontology is 

 recognized in " Cosmos," but is treated almost as if it were a new 

 science. Agassiz's work on " Fossil Fishes," in which more than 1,700 

 species were described, is given the honor it deserves. But open minded 

 as Humboldt was to every suggestion of scientific men and ready to 

 accept any well-authenticated statement, he was very cautious about 

 departures from old and prevailing theories. Since his time, meteorol- 

 ogy, as he predicted it would, has become a science of much practical 

 value. Geology, mineralogy and paleontology have made giant strides. 

 Chemistry has almost entirely changed its character, even its termi- 

 nology has become new. The advance in physics almost defies descrip- 

 tion. Since Humboldt died Lord Kelvin, Clerk Maxwell of Edinburgh 

 and Herz of Germany have done their epoch-making work on light. 

 Lines of magnetic force and the character of the magnetic field are 

 better understood than when Faraday gave his attention to them and 

 through his discoveries received the warmest praise from Humboldt. 

 Electricity as a science and in its practical applications has developed 

 one might say almost entirely since 1859. Of radium and radio-activity, 

 whose secrets Monsieur and Madame Curie and Eutherford have done 

 so much to make known, Humboldt knew nothing. Nor had he any 

 conception of the character and extent of the revelations from the 

 heavenly bodies which studies in astro-physics have brought. But of 

 science as it was in his day, and for some years after his death, he was 

 a master and as competent as he himself believed and as others admit 

 him to have been to make such general statements concerning its 

 triumphs and promise as to show the careful reader of " Cosmos " even 

 now the foundations upon which the scientific progress of the last half 

 century has rested. 



