158 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 70 



Africa, and in North America, he found that in all of these seven 

 regions the temperature nearly simultaneously sank. The tempera- 

 ture decrease in Germany amounted to more than 2° C. Neverthe- 

 less he found a rise in the temperature toward the end of the year 

 that did not correspond with variations in the observed value of the 

 solar constant. This he explained by increased tranparency in the 

 atmosphere which had been noticed in September of this year. 



Though Langley stated these results with great reserve and cau- 

 tion, they seem to indicate that the temperature on the surface of the 

 earth varies directly with the solar radiation, a conclusion which, 

 however, was strongly shaken by later investigations. 



Abbot and Fowle (1908) collected the anomalies of monthly 

 temperature for forty-seven stations in different parts of the earth. 

 Since they assumed that the temperature of the earth would vary 

 directly with the variations in the received solar radiation, they 

 chose stations which were inland as far as possible, where the direct 

 solar radiation would make itself most felt without experiencing 

 much the equalizing influence of the ocean. 



Their forty-seven stations were ranged in eight regions : North 

 America (15), South America (i), middle and east Europe (8), 

 North Africa (2), South Africa (2), North Asia (7), South 

 Asia (6), Australia (6). The curves for each of these regions ap- 

 pear to be very irregular, but the mean for each year for all regions 

 and all temperatures shows an eleven-year period that varies op- 

 positely to the sun spots. Their curve (1908, pi. XXV-A) shows 

 also well-marked three or four divisions of the eleven-year period, 

 particularly in the last period, 1889 to 1900. Though they do not 

 call attention to this, it seems very similar to the periods of sun spots,- 

 prominences, and magnetic elements as shown in our figure 95. In 

 this publication these authors are inclined to the view that tempera- 

 ture variations follow directly variations of the solar radiation re- 

 ceived, and consequently that this will be less at sun spot maxi- 

 mum, which, however, is a view they later found to be erroneous 

 (1913-a). 



In a later work (1913-b) Abbot and Fowle investigated the de- 

 pendence between volcanic eruptions and variations in the air tem- 

 perature of the earth. They came thereby to the conclusion that the 

 solar radiation which reaches us is diminished by the masses of 

 volcanic dust, which are thrown out by powerful explosive volcanic 

 eruptions and distributed at great heights in the atmosphere. Such 

 eruptions are those of Krakatao in August 1883, Mt. Pelee (Mar- 



