114 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. JO 



This transportation of cold water-masses from the north toward 

 the south by the wind involves this peculiarity, that the more north- 

 erly water-masses are generally in consequence of their lower 

 temperature of a higher density than the southerly and warmer 

 water-masses. The northerly water-masses can therefore not be 

 driven by the wind over the surface of the southern layers, but have 

 a tendency to sink below them though obviously there is a tendency 

 for these layers to mix by the action of the waves. Winds which 

 bring colder water into the region of warmer will therefore not 

 so easily produce considerable variations in the surface temperatures 

 as winds which blow water in the reverse direction from warmer 

 regions toward colder. On the other hand those winds which 

 transport colder water towards warmer regions of the sea have a 

 tendency to produce variations of the temperature in the upper 

 layers of the ocean underneath the surface, since by such winds 

 convection currents are set up in a vertical direction. But they 

 have also the tendency to carry the warmer water-masses of the 

 surface with them toward the south and to replace them with cooler. 



THE VARIATIONS IN HEIGHT OF THE WATER OF THE BALTIC SEA AS 



A PROOF OF THE ACTION OF THE WIND ON THE VARIATIONS OF 



THE SURFACE TEMPERATURE OF THE NORTH ATLANTIC 



That the winds are a strongly contributing cause of the observed 

 variations in the surface temperature in the Atlantic Ocean seems 

 to be shown by the notable agreement between the variations of 

 the temperature condition of the Atlantic Ocean in February and 

 the variations of the average height of the water for the whole 

 year in the North Sea and particularly in the Baltic Sea. We found 

 that if the surface temperature in the Middle Atlantic Ocean in 

 comparison with that on the east shore of the ocean in February 

 was low, then the yearly mean height of the water in the North 

 Sea, particularly in the Baltic Sea, and partially also on the Nor- 

 wegian coast was high ; while if the surface temperature was high 

 in the middle of the Atlantic Ocean in comparison with that at the 

 shore of it the reverse condition was found. That the winds are 

 of importance for this relation cannot be doubted. For we know 

 that the height of the water along the coast depends upon the air 

 pressure distribution and upon the winds, and it is therefore to be 

 assumed that the observed variations in the average height of the 

 water in the No'rth Sea and in the Baltic Sea is brought about in this 

 way. We must therefore logically conclude that the same cause 



