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THE AMERICAN MUSEUM JOURNAL 



art' all sorts of apparent contradictions. 

 For instance, it has been proved l)eyond 

 Cjuestion that when sunspots are numer- 

 ous the temperature of the earth's sur- 

 face is lower than usual, and that it rises 

 steadily toward a maximum at the time 

 when the sunspots are at a minimum. 

 This looks like a clear case of solar 

 control of terrestrial climate. To be 

 sure the difference between the tempera- 

 tures at maximum and minimum spots 

 is scarcely a degree Fahrenheit, but that 

 is enough to be significant. The ap- 

 parent agreement between sunspots and 

 temperature however, has been more of a 

 puzzle than a help in solving the prob- 

 lem of the causes of climatic changes, 

 ('areful measurements of the sun's 

 radiation at several observatories have 

 shown beyond ciuestion that when sun- 

 spots are numerous, the sun sends out 

 more heat than usual, whereas the earth 

 is cooler than usual. 



Many similar contradictions are found. 

 For instance, tropical hurricanes in- 

 crease in close harmony with the num- 

 ber of sunspots. The same is true of 

 tropical rainfall in general, when the 

 whole torrid zone is considered. In 

 indi\iflual areas however, the opposite 

 condition is found to prevail. Again, 

 the le\el of Lake Michigan has been 

 carefully recorded for many years. 

 When it is compared with the sunspot 

 numbers from 18()() to lOlf) the two go 

 up and down approximately together 

 from 1800 to 1872; then they disagree 

 markedly for eight years; next they go 

 together for twelve years or till 1890; 

 again there is a disagreement for about 

 eight years; then comes agreement for 

 thirteen years until 1911; and finally 

 four years of disagreement. That is, 

 the lake level and the sunspot numbers 

 \'ary in fairly close harmony for about 

 thirty-eight years and fail to agree for 

 about eighteen years. There is enough 



agreement strongly to suggest a real 

 relationship, but enough disagreement 

 to warrant grave doubts. 



Still anotlier puzzling feature is found 

 in the degree of storminess in the United 

 States. The statistics of the Weather 

 Bureau show c|uite clearly that when 

 sunspots are numerous there are more 

 storms in the I'nited States as a whole 

 than when the spots are few. In Ari- 

 zona on the one side and in southern 

 Canada on the other, the figures for 

 successive years bear this out; but in 

 Kansas the opposite is true, for the 

 number of storms tends to decrease in 

 3'ears of many spots. Obviously we are 

 dealing with a very complex matter. 



Another type of relationship between 

 the sun and the earth has been found by 

 Arctowski. From a careful study of 

 many records he finds that temperature, 

 barometric pressure, rainfall, and other 

 meteorological conditions vary regularly 

 in little cycles having a length of from 

 two to three years. These variations 

 are so uniform in widely separated 

 latitudes and longitudes that they can 

 scarcely be due to anything except soine 

 outside cause such as the sun. More- 

 over they seem to agree with some of the 

 minor fluctuations of the sun, such as 

 the prominences, as has been shown by 

 See. Here again there seems to be an 

 unquestionable connection between the 

 earth and the sun, but it also is beset 

 with contradictions. In certain areas 

 Arctowski's little variations, which he 

 calls pleions, lag behind the standard 

 series which is most clearly developed 

 in tropical countries. What seems to 

 happen is that certain parts of the 

 earth's sm-face where the sun is shining 

 with full force, for instance the equa- 

 torial zone or the interior of a continent 

 during the summer, become highly 

 heated when the sun is imusually active. 

 The heat thus received moves slowlv 



