PREHISTORIC SCIENCE 



and the reports of travellers, there was nothing to sug- 

 gest to early man the limit of the earth. He did, in- 

 deed, find in his wanderings, that changed climatic con- 

 ditions barred him from farther progress; but beyond 

 the farthest reaches of his migrations, the seemingly 

 flat land-surfaces and water-surfaces stretched away 

 unbroken and, to all appearances, without end. It 

 would require a reach of the philosophical imagination 

 to conceive a limit to the earth, and while such imag- 

 inings may have been current in the prehistoric period, 

 we can have no proof of them, and we may well post- 

 pone consideration of man's early dreamings as to the 

 shape of the earth until we enter the historical epoch 

 where we stand on firm ground, ja-u/v- 



2. Primitive man must, from a very early period, 

 have observed that the sun gives heat and light, and 

 that the moon and stars seem to give light only and 

 no heat. It required but a slight extension of this 

 observation to note that the changing phases of the 

 seasons were associated with the seeming approach and 

 recession of the sun. This observation, however, 

 could not have been made until man had migrated 

 from the tropical regions, and had reached a stage of 

 mechanical development enabling him to live in sub- 

 tropical or temperate zones. Even then it is con- 

 ceivable that a long period must have elapsed before a 

 direct causal relation was felt to exist between the 

 shifting of the sun and the shifting of the seasons; 

 because, as every one knows, the periods of greatest 

 heat in summer and greatest cold in winter usually 

 come some weeks after the time of the solstices. Yet, 

 the fact that these extremes of temperature are asso- 



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