NO. 4 TEMPERATURE VARIATIONS IN THE NORTH jVTLANTIC I73 



United States the air pressure varied directly and the temperature 

 oppositely as the sun spots and the magnetic forces. He also noted 

 the shorter variations of a few years' period which he estimated 

 at two and three-fourths years, and from this he concluded that 

 there are four such periods in the eleven-year sun spot cycle. This 

 is, as a comparison of the Bigelow curves with those of the two 

 Lockyers shows, exactly the same short period that the Lockyers 

 observed and whose duration they assigned at three and a half or 

 3.7 years. This w'ell-marked period was also clearly shown in 

 Bigelow's curve of 1894. The differences in the determination of 

 its length are dependent upon the fact that the two Lockyers assume 

 that there are three such periods in the eleven-year sun spot period. 

 This was indeed the case in the time interval 1880 to 1890, which 

 was the one principally investigated by them. Bigelow found also 

 (1902, 1903) the same opposing relation which the two Lockyers 

 had found between the air pressure variations in the different parts 

 of the earth. He divided these variations into three kinds: First, 

 those where the variation goes directly with the prominences ; second, 

 where it goes opposed to the prominences ; and third, those in which 

 now one and now the other type prevails and which he spoke of as 

 the indifferent type. The charts which he gives illustrating the dis- 

 tribution of these different types of air pressure variations agree in 

 general with the charts which the two Lockyers published in the fol- 

 lowing years. 



Later (1908) Bigelow found that while the air pressure varia- 

 tions for the eleven-year period over the whole United States go 

 in opposite direction to the sun spots and the prominences, it is 

 otherwise with the short period of about three years, for in this 

 they have the same direction as the prominences in the western 

 United States and the Pacific Ocean, while they go in the opposite 

 direction to the prominences in the states east of the Rocky Moun- 

 tains. As already remarked, Bigelow is of the impression that 

 the variations in the air pressure over the earth and particularly in 

 the United States depend in great part on variations in what 

 he calls " magnetic radiation " of the sun. This radiation influences 

 directly, he thinks, the air pressure and the atmospheric circula- 

 tion and thereby indirectly affects the temperature. 



Dr. Richter (1902) compared five yearly smoothed curves of 

 air pressure at different stations in Europe with curves for the sun 

 spots, the Northern Lights, and the yearly variations magnetic 

 dechnation for a series of years from about 1830 to about 1880. 



