336 PHYSICAL GEOGRAPHY. 



its meridian altitude. According to the testimony of navi- 

 gators (Scoresby, Parry, Ross, and Franklin), as collected 

 by Arago, it is undoubted that in general in the high northern 

 regions, between 70 and 75 of latitude, electric explosions 

 are exceedingly rare. ( 418 ) 



The meteorological portion of the description of nature, 

 which we are now concluding, shews thatthe various processes 

 which the vast aerial ocean presents, the absorption of 

 light, the disengagement of heat, the variation of elastic force, 

 the hygrometric condition, and the electric tension, are all so 

 intimately connected, that each separate meteorological pro- 

 cess is simultaneously modified by all the rest. This com- 

 plexity of disturbing causes, (which reminds us involuntarily 

 of those which the near, and especially the small, cosmical 

 bodies, the satellites, comets, and shooting stars, encounter in 

 their course through space), makes it very difficult to give 

 the full interpretation of meteorological phsenomena; and 

 the same cause greatly limits or wholly precludes the possi- 

 bility of that prediction of atmospheric changes, which would 

 be so important for agriculture and horticulture, for navi- 

 gation, and for the convenience and pleasures of life. Those 

 who place the value of meteorology not in the knowledge of 

 the phsenomena themselves, but in this problematical power 

 of prediction, are imbued with a firm persuasion that this 

 branch of science, for the sake of which so many journeys 

 in distant mountain regions have been undertaken, has for 

 centuries achieved no progress whereof to boast. The confi- 

 dence which they refuse to physical philosophers they bestow 

 on changes of the moon, and on certain days long marked 

 in the calendar. 



Great deviations from the mean distribution of teua- 



