486 E. HUNTINGTON SOLAR HYPOTHESIS OF CLIMATIC CHANGES 



temperature, as is evident from the fact that in figure 1 the sun-spot 

 curve has had to be inverted in order to correspond to the temperature 

 curve. This does not mean that the slight additional heat received from 

 the sun during times of many sun-spots does not produce its due effect 

 in warming the earth. It merely suggests that at the times when the sun 

 is active and is unusually well supplied with spots two agencies are at 

 work in modifying the earth's temperature. One of these is the increased 

 temperature of the sun's surface ; but the effect of this is so small that it 

 is not merely nullified, but actually reversed by the other agency. Wliat 

 that other agency may be we must now proceed to investigate. 



The experiences of every day show that tlie temperature of any part 

 of the earth's surface depends on two chief factors : One of these is the 

 amount of heat received from the sun ; the other is the winds, which not 

 only act directly, but which cause ocean currents, and thus transport 

 large bodies of heat from equatorial regions to ])laces such as the Xortli 

 Atlantic and western Europe. If variations in the actual mean tempera- 

 ture of the sun are too small to be of appreciable importance, as they 

 seem to be, the winds remain as by far the most important determinant 

 of variations in terrestrial temperature. Their importance seems greater 

 than is often realized, for they carry heat from place to place not only 

 horizontally, as is universally recognized, but also vertically — a fact which 

 people who are not meteorologists are apt to lose sight of. The intensity 

 of both kinds of movement may and does vary. Our task will be to see 

 wliat connection this appears to have with changes in the sun and then 

 with possible causes of glaciation. 



Present staUis of the solar hypothesis — Newcomb's conclusions as to 

 temperature. — Before proceeding to this task, it is necessary to obtain a 

 clear conception of the exact status of our present knowledge of the rela- 

 tion of sun-spots and climate and of the reasons for and against l)elieving 

 that any relation really exists. In considering this the reader must re- 

 member that previous studies have been based on the natural assumption 

 that if such a relationship exists it must be due to changes in solar tem- 

 perature. According to the hypothesis here to be developed, on the con- 

 trars% it may be due merely to a redistribution of the present amount of 

 heat, both horizontally and vertically. 



One of the most thorough investigations of the relation of solar and 

 terrestrial phenomena was made by N'ewcomb.^*' His conclusions arc 

 based on a comprehensive study of terrestrial temperatures at periods of 



'*» A soarch for fluctuations in the sun's thermal radiations through their influence on 

 terrestrial temperature, by Simon Newcomh. Trans. Am. Phil. Soc. n. s.. vol. 21. 100«. 

 p. V. 



