122 ABOUT THE WEATHER. 



earth, that blowing from the poles to the equator, and 

 that returning to the poles. Let us imagine a place in the 

 region of what I have called the changeable weather, say 

 in Germany, and let us assume that this spot lies directly 

 in the direction of the Polar current. A north wind blows, 

 the air is cold, the sky serene and remaining so while the 

 wind gradually changes, and at last appears as a true east 

 wind, the dry, highly oxygenated Polar air of which is so 

 perilous to those whose lungs are affected. This wind 

 blows until another replaces it, and this is none other 

 than the Equatorial current which always begins as a 

 south wind, and the meeting of this with the east pro- 

 duces the south-east wind, having an intermediate direc- 

 tion ; in this the moist, warm air of the Equatorial current 

 is cooled down by the cold Polar current, and constrained 

 to deposit part of the water it contains in the form of 

 clouds, snow or rain. Gradually the Equatorial current 

 acquires the mastery ; in the south wind it becomes warm 

 and bright and so remains till the Equatorial current 

 gradually diverges round to the west. The northern Polar 

 current alone can take its place at a change, and the mixture 

 of this with the moist air in the north-west wind, again 

 gives rise to abundant atmospheric precipitation. These 

 are the cold, damp days in which those persons suffer so 

 much who have nervous complaints. 



Thus it goes on, in the same order, which is now first 

 scientifically enounced from the long known facts, in 

 that which Dove has named the law of the circulation of 

 the wind, and we can now prophecy the weather with great 

 certainty even in these regions, only not for defined periods 

 of time, since we are ignorant of the circumstances regulat- 

 ing the duration of one or other current in their strifes in 

 the south-east or north-west quadrants. 



