52 COLONSAY 



overestimate the rainfall of many localities ; the eighties, a 

 dry decade that would cause us to underestimate it. 



Winds. In the more exposed of the Western Isles the 

 prevalence of strong winds has a most detrimental effect 

 on the growth of many plants, particularly those that are 

 not native but have been introduced to the islands. During 

 the early part of the growing season the tender leaves and 

 shoots of trees in exposed positions become prematurely 

 battered and brown, and are rendered unfit for carrying on 

 the complicated processes that are so vital to the well- 

 being of the plant. Not infrequently the young leaves are 

 torn off the trees by the force of the wind before they are 

 fully developed. Owing to the preponderance of westerly 

 winds, trees in exposed positions acquire a characteristic 

 one-sided shape, the greater part of their development being 

 in the easterly direction. Autumn gales frequently damage 

 the fruit crop by stripping the fruit off the trees. Often 

 when a gale or stormy weather is approaching from the west 

 a rising swell on the sea gives premonitory warning of its 

 advance several days beforehand, even though the air around 

 may be comparatively still. 



Directions from which the wind blew at Du Hirteach 

 Lighthouse (15 miles W.N.W. of Colonsay) during 1898 : 

 K, 44 days; N.E., 19 days; E., 28 days; S.E., 37 days; 

 S., 58 days ; S.W., 69 days ; W., 59 days ; N.W., 49 days ; 

 calm or variable, 2 days. 



Sunshine. The percentage of sunshine on the West Coast 

 is greater than might be expected, taking into consideration 

 the heavy rainfall of the West Coast when compared with 

 that of the East. In 1906 bright sunshine at Oban was 

 28 per cent (average rainfall 60 inches), and in Edinburgh 

 31| per cent (rainfall 26 inches). The average sunshine for 

 Stornoway for 25 years is 29 per cent. In spring, when 



