50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 70 



cannot be decided with certainty." The last remark can scarcely 

 be entirely correct, for the action cannot be equally strongly distri- 

 buted at all times, but must be greatest behind the stronger winds. 



The only published observations on variations of the intensity of 

 the southeast trade winds relate to St. Helena, for the years 1892 to 

 1898 and are very insufficient for a proper comparison between the 

 relations of the wind and temperature variations. They can only 

 give certain qualitative impressions without elevating the investiga- 

 tion to a quantitative basis. 



W. Koppen has investigated the question " On What is the High 

 Temperature of Europe and the North Atlantic Dependent?" 

 (1911). He arrives at the conclusion that in part at least the varia- 

 tions of the yearly seasons depend upon the cloudiness which in 

 Europe is greatest in the winter and least in summer, both condi- 

 tions tending to an increase of the temperature. Furthermore, he 

 attributes a part to the prevailing winds which are southwesterly. 

 Of far the most considerable influence on the high temperature in 

 Europe are the warm ocean currents which bathe the west and 

 northwest coast. Koppen does not deal with the periodic and non- 

 periodic variations, but contents himself with a statement that it 

 has long been known that the simple nearness of warm water and 

 its action on climate is not decisive, but that the direction of prevail- 

 ing winds makes it influential. He says, " their influence can only 

 be felt when it is borne by the winds.'" He thinks besides that there 

 cannot yet be accurately estimated the relative efifects on the warm- 

 ing of Europe of the different factors, the water-masses of the Gulf 

 Stream, the prevailing winds, and the cloudiness, even though one 

 should be satisfied with a rough approximation. 



Commander Campbell Hepworth, (1910) compared the variation 

 in the surface temperature in the North Atlantic with the variation 

 of the strength of the trade winds. He is of the opinion that there 

 is a distinct dependence between the two, and such that variations 

 in the strength of the northeast and southeast trade winds in a series 

 of months or in a single month are roughly mirrored by the dis- 

 tribution of surface temperatures of the North Atlantic Ocean in 

 the corresponding series of months or single month of the follow- 

 ing year. That the dependence is not always distinct, he attributes 

 to the fact that many other causes influence the temperature of the 

 ocean surface, and tend to hide the influence he points out. Particu- 

 larly the activity of the Labrador Stream and the Gulf Stream are 

 of importance in this connection and also the strength and duration 



