PKEBEIs^T STATUS OF SOLAR HYPOTHESIS 489 



himself guardedly. On page 341 of tlie work already cited, Neweoiiib 

 says: 



"Altboiigli the reality of this 11-year fluctuation [both solar and terrestrial] 

 seems to be beyond serious doubt, the amplitude being several times its prob- 

 able error, its amount is too small to produce any important direct effect upon 

 meteorological phenomena." 



Again, on page 384, he puts in italics the last part of the following 

 quotation : 



"It follows as the final result of the present investigation that all the ordi- 

 nary phenomena of temperatitre, rainfall, and winds are due to purely terres- 

 trial causes, and that no changes occur in the sun's radiation which have any 

 influence upon them J' 



N"ewcomb's opinion carries great weight. Nevertheless, while his con- 

 clusions as to the difference in temperature between periods of maximum 

 and minimum sun-spots seem to be unassailable, his conclusion as to 

 changes in meteorological phenomena stands on quite a different basis. It 



following table, which I have modified so as to place the sun-spot cycles in the order 



Difference between temperature at times of 

 maximum and minimum spots. 



of their intensity. 



Difference between 



First year of maximum and '^- ^ 



sun-spot cycle. minimum sun-spot ABO 



numbers. North '^Vyr^r^^nai South 



Temperate 7^!!o Temperate 



Zone. ^*^"^- Zone. 



1833 126 ■ 2.2 5.1 



1867 .' 126 -0.1 1.7 2.9 



1844 116 0.5 ' 1.5 2.2 



1855 88 2.8 1.2 2.0 



1889 80 0.6 2.4 1.7 



1822 61 1.4 2.4 



1878 59 1.8 2.1 1.3 



1811 45 3.2 



In the north temperate and tropical zones the table supports Koppen's conclusion, 

 but in the south temperate zone there is a perfectly regular decrease in range of tem- 

 perature in harmony with the decrease in range of spottedness. The north temperate 

 and tropical zones contain large masses of land, and the figures for temperature repre- 

 sent the conditions as influenced by the irregular circulation and other peculiar condi- 

 tions of continents. The south temperate zone contains so little land that it may be 

 regarded as representing marine conditions. If similar conditions are characteristic 

 of the ocean as a M^hole — except in the parts where large bodies of heated water are 

 brought in from other latitudes — the mean temperature of the entire earth would prob- 

 ably rise and fall in harmony with the sun-spots, not only when parts of the same 

 sun-spot cycle are compared, but when different cycles are compared. 



The last part of KOppen's paper is devoted to a discussion of the effect of volcanoes 

 on temperature. He comes to the conclusion that no important effect seems as yet to 

 be proved. He bases this chiefly on the fact that if volcanic dust is a main factor in 

 causing a reduction of temperature, years showing a large minus departure of tempera- 

 ture ought to be more numerous than years showing a large plus departure. The 

 contrary is the case. 



11'' Henryk Arctowski : L'Enchainment des variations climatiques Bruxelles, 1909. 



