NO. 4 TEMPERATURE VARIATIONS IN THE NORTH ATLANTIC I7I 



As above indicated, there occurred in 1894 or 1895 a remarkable 

 break in the regularity of the curves of the two kinds of spectro- 

 scopic lines for sun spots and at the same time there occurred ac- 

 cording to the meteorological publications of India irregularities in 

 the precipitation there. Besides it is to be remarked, although not 

 called attention to by the Lockyers, that for the years after 1890 both 

 the summer and the winter curves of air pressure in Bombav run 

 in opposite direction to the variations in the prominences, while the 

 curve for April to September for Cordoba runs in the same direction 

 as the variations of the prominences for these years. That is to 

 say, the curves for the two stations from this time are relatively 

 inverted.* 



Later (1904-1908) Sir Norman and William Lockyer have ex- 

 tended their investigations to other regions of the earth and found 

 that the two opposite types of air pressure variations have very wide 

 extensions. The region in which the air pressure varies directly 

 with the prominences extends over the whole Indian Ocean, Aus- 

 tralia, South Africa, northwards over Arabia, Persia, North Africa, 

 South Europe to Iceland and Greenland, and from there further 

 over the region of Northern Canada to Alaska, while in South 

 America, Western North Africa, the greater part of North Amer- 

 ica and the Pacific Ocean, as well as in east Asia, Siberia, and the 

 most northerly part of Russia and of Scandinavia the air pressure 

 variations are generally inverted with respect to the prominences. 

 In one part of this region, as for example in southwest and middle 

 Europe, most easterly Canada and other places, the variations run 

 partly in one and partly in the other direction and the curves which 

 express the variations in these regions have therefore a mixed type. 

 As we shall see, this division of the earth into different regions 

 where the variations have opposing directions agrees in its princi- 

 pal feature with Hildebrandsson's division of the earth's surface 

 into different action centers where the variations occur inverted. 



There appears to be a conflict between this result of the two 

 . Lockyers, that in India the air pressure in their three years' period 

 varies directly with the prominences and. for example, in Siberia 

 oppositely, and the proof which Chambers, Broun, Hill, Archibald, 

 Blanford and others have furnished that in the eleven-year sun 

 spot period the pressure in India varies in the opposite direction to 



* It is, however, worth noting that the air jiressure curves for Bombay in this 

 time had in part a better direct agreement with tlie curves for the variations 

 of the heliographic latitudes of sun spots. 



