286 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 70 



ing during this period, with increasing values. In September and 

 October, 1909, the values of the '' solar constant " seem likewise on 

 the whole to have been decreasing while the values of pressure dif- 

 ference and temperature were on the whole increasing. 



Most curves, the temperature and pressure curves as well as the 

 solar curves, show indications of a period varying in length, mostly 

 between 25 and 27 or 28 days, in most cases about 27 days. There 

 are also frequent indications of a subdivision o'f this longer period 

 into a shorter period of half the length. 



The above results, that the pressure gradient as well as the tem- 

 perature at Bergen vary, on the whole, directly as the solar radia- 

 tion, agree with our earlier results obtained by a comparison be- 

 tween the monthly fluctuation in the relative numbers of sun spots, 

 and the monthly fluctuations in the pressure gradient of the North 

 Atlantic and in the temperature of Norway. We found (cf. fig. 92, 

 curves III, IV, and V) that especially during the period 1903 to 

 1911, the fluctuations in the sun spots from month to month are 

 as a rule repeated directly in the fluctuations of the pressure gradi- 

 ent, and of the temperature in Norway. The latter fluctuations 

 occur often a short while after those of the sun spots. We also 

 found that especially during the said period there was a conspicu- 

 ous period of eight months in the fluctuations in sun spots as well as 

 in the fluctuations in the pressure gradient and in the temperature 

 of Norway (cf. fig. 92). 



FLUCTUATIONS IN AIR PRESSURE AND SUN SPOTS STUDIED BY 

 TWELVE-MONTH MEANS 



We have continued our investigations, by means of consecutive 

 twelve-month means, on the fluctuations in temperature and air 

 pressure at stations in dififerent regions of the globe. 



We much regret that for very important high-pressure as well as 

 low-pressure regions of our globe there are no satisfactory series 

 of barometric observations at hand. We may especially mention 

 the Pacific Ocean, the tropical low-pressure region of the Atlantic, 

 the high-pressure region of the South Atlantic and the Indian Ocean, 

 the antaretic low-pressure regions. It is therefore not possible, 

 at present, to discuss the barometric fluctuations (at the earth's sur- 

 face) of the atmosphere as a whole. We have been obliged to 

 limit our investigations to a comparatively small portion of the 

 globe's surface. 



