THE CENTURY'S PROGRESS IN METEOROLOGY 



bilities that the science of the future may reveal associa- 

 tions between the weather and sun-spots, auroras, and 

 terrestrial magnetism that as yet are hardly dreamed of. 

 Until such time, however, these phenomena must feel 

 themselves very grudgingly admitted to the inner circle 

 of meteorology. More and more this science concerns 

 itself, in our age of concentration and specialization, 

 with weather and climate. Its votaries no longer con- 

 cern themselves with stars or planets or comets or shoot- 

 ing-stars once thought the very essence of guides to 

 weather wisdom ; and they are even looking askance at 

 the moon, and asking her to show cause why she also 

 should not be excluded from their domain. Equally 

 little do they care for the interior of the earth, since 

 they have learned that the central emanations of heat 

 which Mairan imagined as a main source of aerial 

 warmth can claim no such distinction. Even such prob- 

 lems as why the magnetic pole does not coincide with 

 the geographical, and why the force of terrestrial mag- 

 netism decreases from the magnetic poles to the mag- 

 netic equator, as Humboldt 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. 



in 



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

 that interested our forebears, whose meteorological im- 

 portance 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 attested by the 

 number of theories then extant regarding it; and these 

 conflicting theories bear witness also to the difficulty 



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