296 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 70 



the thirty-six-month means, in order to eliminate the longer periods 

 (cf. fig. 94, MK, fig. 96, I, III). 



There is undoubtedly to a certain extent, an agreement between 

 these two curves and the barometric curves I-IX (fig. 107) for 

 high-pressure regions as well as low-pressure regions of our globe. 

 In some years the maxima or minima of the solar and magnetic 

 curves are found in all barometric curves I-IX (e. g., the maxima 

 C, K, R, S, the minima h, r) , while in other years the maxima and 

 minima of curves S and M are only found in some barometric 

 curves (e. g., the maxima B, E, G, H, L, M, P, etc). 



It may be noticed that according to all these curves the baro- 

 metric fluctuations occur always somewhat later, and often several 

 months later, than the corresponding fluctuations in sun spots, and 

 in magnetic declination at Christiania. 



On the other hand it may also be noticed that some barometric 

 fluctuations, especially the maximum of the high-pressure regions 

 (fig, 107) and the minimum of the low-pressure regions (fig. 108) 

 of 1878-79, and the minimum of the high-pressure regions and the 

 maximum of the low-pressure regions of 1880-81, do not correspond 

 to any similar fluctuations in sun spots and magnetic declination, as 

 exhibited by our curves in figure 107, though there may possibly be 

 some slight indications in curve M. 



On the whole, however, figure 107 demonstrates that there is the 

 same rhythm in the barometric fluctuations as in the fluctuations of 

 sun spots and magnetic declination, and we may infer that an in- 

 crease of solar activity causes on the average an increase of atmos- 

 pheric circulation of our globe by raising the chief barometric 

 maxima and lowering the chief minima. 



FLUCTUATIONS IN TERRESTRIAL TEMPERATURES COMPARED WITH 



FLUCTUATIONS IN AIR PRESSURE AND SOLAR RADIATION 



STUDIED BY TWELVE-MONTH MEANS 



According to the results of our investigations, as described before 

 in this paper, the fluctuations in temperature at the earth's surface 

 are chiefly due to fluctuations in the atmospheric circulation, which 

 again are caused by variations in solar radiation. The nature of 

 the changes of temperature at the various stations, whether posi- 

 tive or negative, depends on the situation of the station in relation 

 to the barometric centers of action. In regions where an in- 

 creased activity of the centers of action will cause more cooling 

 winds, the effect will naturally be a lowering of temperature, and 



