212 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 70 



THE AIR PRESSURE VARIATIONS AND THE VARIATIONS IN SOLAR 

 ACTIVITY. CONFUTATION OF EARLIER AUTHORS 



As remarked above, an apparent contradiction exists among the 

 results of earlier investigators with reference to the periodicity of 

 air pressure variations in dififerent regions of the earth. On the 

 one hand, Chambers, Broun, Hill, Blanford and others found that 

 the air pressure variations, for example in the Indo-Malayan region, 

 have an eleven-year period during which the air pressure varies 

 oppositely to the sun spots, while the variations occur in the same 

 sense as sun spots in west Siberia, in Russia, etc. On the other 

 hand both Lockyers found a three year or 3.7 year period in the air 

 pressure variations in Bombay and the Indo-Malayan region in 

 which the air pressure varies directly with the prominences. In 

 other words the air pressure variations appear to go in these short 

 periods directly as the variations of solar activity and opposite to 

 the co'urse which they follow in the longer period of eleven years. 



Examining this matter more closely, we find, as remarked above, 

 that the curves published by the two Lockyers (1902, p. 501) show 

 not so complete an agreement between the variations of the promi- 

 nences and the air pressure variations as one would have expected 

 from their publication. In the period from 1880 to 1890, which 

 the two Lockyers investigated, the observations of the Osserva- 

 torio del Collegio Romano show three very well-marked periods in 

 the prominences in the run of the eleven-year sun spot period, and 

 in the same time interval there appear air pressure variations in 

 Bombay with corresponding periods. But in the time after 1890 the 

 Lockyers' own curves show that the air pressure in Bombay varied 

 oppositely to the prominences. This appears also in our figure 71, 

 where curve VIII-B indicates the air pressure variations in Bom- 

 bay and the curves R and T-C show the variations in the promi- 

 nences. The curves R are according to the observations of the 

 Osservatoria del Collegio Romano and P-C the observations in 

 Palermo and Catania (see pi. 20-S).'' While the Roman promi- 



^ In " Memorie delta Societa degli Spettroscopisti Italiani " the Italian as- 

 tronomers Tacchini, Ricco, and in part also Mascari, have given papers on the 

 observations of the solar prominences in the observatories of Rome, Palermo 

 and Catania for the years from 1871 till the present. But the observations 

 extend over unequal numbers of years for the different observatories. In 

 Rome the publications extend from the year 1871 to 1900; for Palermo, from 

 1878 to 1893 ; and for Catania for all years since 1892. According to these 

 reports we have prepared an illustration of the number of observed promi- 

 nences per observation day for each month and for each observatory. It 



