THE CENTURY'S PROGRESS IN METEOROLOGY 



one. Little danger that the memoirs of such a band 

 would be relegated to the dusty shelves where most 

 proceedings of societies belong no milk-for-ba^es fare 

 would be served to such a company. 



The particular paper which here interests us closes 

 this third and last volume of memoirs. It is entitled Des 

 lignes isothermes et de la distribution de la chaleur sur le 

 globe. The author is Alexander Plumboldt. Needless 

 to say, the topic is handled in a masterly manner. The 

 distribution of heat on the surface of the globe, on the 

 mountain-sides, in the interior of the earth ; the causes 

 that regulate such distribution; the climatic results 

 these are the topics discussed. But what gives epochal 

 character to the paper is the introduction of those iso- 

 thermal lines, circling the earth in irregular course, join- 

 ing together places having the same mean annual tem- 

 perature, and thus laying the foundation for a science of 

 comparative climatology. 



It is true the attempt to study climates comparatively 

 was not new. Mairan had attempted it in those papers 

 in which he developed his bizarre ideas as to central 

 emanations of heat. Euler had brought his profound 

 mathematical genius to bear on the topic, evolving the 

 " extraordinary conclusion that under the equator at 

 midnight the cold ought to be more rigorous than at 

 the poles in winter." And in particular Richard Kir- 

 wan, the English chemist, had combined the mathemat- 

 ical and the empirical methods, and calculated temper- 

 atures for all latitudes. But Humboldt differs from all 

 these predecessors in that he grasps the idea that the 

 basis of all such computations should be not theory, but 

 fact. He drew his isothermal lines not where some oc- 

 cult, calculation would locate them on an ideal globe, 



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