CLIMATE 47 



Formerly the mildness of our winters was generally 

 attributed to the influence of the Gulf Stream, which was 

 supposed to flow across the Atlantic in a never-ending stream 

 of warmer waters to our shores. This long-established 

 theory has of late years lost its weight with many investi- 

 gators. It is found that the Gulf Stream has almost ceased 

 to exist a little to the east of the Banks of Newfoundland ; 

 and the most recent authorities attribute the favourable 

 temperature conditions of the North Atlantic directly to 

 the influence of the prevailing south-westerly winds, and 

 indirectly to a surface drift of warmer waters which these 

 winds drive before them. The prevailing winds on the 

 American side of the Atlantic, on the other hand, are from 

 the north-east, bringing to lower latitudes the icy conditions 

 of the Arctic Circle. The prevalence of our balmy south- 

 westerly winds is due to the existence of a permanent area 

 of high pressure near the Azores, and a permanent area 

 of low pressure near Iceland. 1 



Although no record of the climate of Colonsay is available, 

 an approximate idea of its character may be formed from 

 the returns of surrounding meteorological stations (v. p. 48). 

 The island's vegetation is also a good indication of the 

 nature of its climate, and if we had no other means of 

 information much could still be learned, with regard to _ the 

 general meteorological conditions prevailing, from a careful 

 survey of the island's flora. Moss- and lichen-coated trees 

 indicate a moisture-laden atmosphere; spongy and mossy 

 pastures, and an abundance of rushes, sedges, and other 

 plants of wet situations point to an unstinted and a well- 

 distributed rainfall. Trees and plantations leaning east- 



1 " Address on the Climate of the British Isles," by Andrew Watt, 

 M.A., F.R.S.E., Secretary of the Scottish Meteorological Society 

 (Scottish Geographical Magazine, April 1908). Much of the informa- 

 tion herein contained has been gleaned from Mr "Watt's interesting 

 paper. 



