THE NEW SCIENCE OF METEOROLOGY 



tinction. Even such problems as why the magnetic 

 pole does not coincide with the geographical, and why 

 the force of terrestrial magnetism decreases from the 

 magnetic poles to the magnetic equator, as Hum- 

 boldt first discovered that it does, excite them only to 

 lukewarm interest; for magnetism, they say, is not 

 known to have any connection whatever with climate 

 or weather. 



EVAPORATION, CLOUD FORMATION, AND DEW 



There is at least one form of meteor, however, of 

 those that interested our forebears whose meteorologi- 

 cal importance they did not overestimate. This is the 

 vapor of water. How great was the interest in this 

 familiar meteor at the beginning of the century is at- 

 tested by the number of theories then extant regarding 

 it; and these conflicting theories bear witness also to 

 the difficulty with which the familiar phenomenon of 

 the evaporation of water was explained^. 



Franklin had suggested that air dissolves water much 

 as water dissolves salt, and this theory was still popu- 

 lar, though Deluc had disproved it by showing that 

 water evaporates even more rapidly in a vacuum than 

 in air. Deluc' s own theory, borrowed from earlier 

 chemists, was that evaporation is the chemical union 

 of particles of water with particles of the suppositi- 

 tious element heat. Erasmus Darwin combined the 

 two theories, suggesting that the air might hold a 

 variable quantity of vapor in mere solution, and in 

 addition a permanent moiety in chemical combination 

 with caloric. 



Undisturbed by these conflicting views, that strange- 



