THE EARTH AND THE SUN 501 



solar data of sun-spots, it is probable that the resemblance between the 

 two curves would he still closer. It may be that the occurience of 

 earthquakes and eruptions lags somewhat behind the change in the 

 number of sun-spots, but the lag is so slight that it does not appear 

 where the unit of measurement is a year, although it might if the 

 unit were a month. It seems to be impossible to avoid the conclusion 

 that the marked coincidence between telluric and solar activity indi- 

 cates a relation of some sort between the internal phenomena of the 

 earth and the sun. 



As to what that relation may be we have as yet no clue. The best 

 that we can do is to speculate. It may be, perchance, that there is 

 some cosmic source of energy as yet unknown, which pulsates through 

 the universe causing both the earth and the sun to respond, each accord- 

 ing to its kind. Possibly changes in the amount or in the nature 

 of the energy emitted by the sun engender corresponding changes in the 

 earth in some manner as yet beyond our ken. 



At the present time, as we have seen, changes in the sun appear 

 to he coincident with climatic and telluric changes in the earth. So 

 far as we can judge, the climatic changes, though on a very small scale, 

 seem to be of the same nature as the great climatic changes of the 

 various glacial periods of earlier geological times. The telluric 

 changes, also on a very small scale, are apparently of the same nature 

 as the great movements of the past by which mountains have been 

 formed and continents uplifted. It is notable that according to the 

 general opinion of geologists the three best known and most severe 

 climatic changes through which the earth has passed have been closely 

 associated with profound modifications of the earth's crust. The 

 glacial period which occurred just before the Cambrian period, far 

 back near the beginning of legible geological records, was followed by 

 a great change in the distribution of land and sea. Again after the 

 prolonged period of comparative stability known as the Paleozoic era 

 there ensued the severe Permian glaciation composed of many glacial 

 epochs separated by warm epochs. At approximately the same time, or 

 shortly afterward, there was a great uplifting of the continents and the 

 formation of mountain ranges such as the Appalachians. Finally the 

 last great glacial period, that of the Pleistocene and Pliocene was also 

 a time of great mountain-building, when the Alps, the Sierra Nevadas, 

 and the Himalayas received a marked uplift giving them their present 

 altitude. 



It thus appears that in geologic history the greatest known climatic 

 changes have been closely associated with remarkable telluric changes. 

 It appears that at present climatic and telluric changes on a small scale 

 are coincident with or follow closely upon changes in the sun. The 

 question at once arises whether there may not have been a similar 



