THE ENGINE OF THE AIR 167 



in vigorous expansion, and the Phoenicians were beginning to 

 explore the western limits of their inland sea. 



During the next millennium, after the warm moist Atlantic 

 period, a warm, dry period held Europe. The lake dwellings 

 grew up in the dried marshes around the Swiss lakes. This was 

 the beginning of the Neolithic culture in Europe, and the 

 so-called Bronze Age in the Mediterranean. As a matter of 

 fact, the ability to smelt bronze from copper and tin and use 

 it for weapons and utensils was probably brought by sea to 

 Europe as the Phoenicians, pushing out from Gibraltar, 

 sought the tin mines of Cornwall and the amber trade of the 

 Frisian coasts of Denmark. 



Then once again a radical fluctuation in the convection 

 system of the Ocean River and its winds must have come on 

 to increase the storm cycles and bring cooler weather and a 

 much heavier precipitation. The times were bad. In the year 

 1275 B.C. the lake dwellers of Switzerland were suddenly 

 flooded out. In the north, a few centuries afterward, the 

 stormy and bitter stretch of years come down to us in legend 

 as the Twilight of the Gods. This held on from 900 b.c. for 

 about five hundred years. 



In other chapters we have watched how the bold Mediter- 

 ranean peoples, enjoying less drastic climatic changes, were 

 pushing out through the Straits of Gibraltar both north and 

 south on tentative explorations of the Atlantic coasts. The 

 first thousand years of the Christian era opened warm and wet 

 for Europe, and then turned warm and dry, with a correspond- 

 ing stimulation in the Scandinavian and Teutonic countries 

 that led to conquests and migrations. Before we follow the 

 effects of the Atlantic storm cycles shifting north or south 

 across Europe we can trace in some detail what a relatively 

 slight improvement in the heating system of the Norwegian 

 Sea and the Arctic accomplished for the Norse. 



In 825 A.D. Irish monks sailed a day northward from Ice- 



