SCOTTISH GARDENS IN GENERAL 



permanent cause of the greater rainfall on our 

 western coasts, as compared with our eastern. 

 Hence, also, their superior mildness in winter; for 

 the latent heat, which was engaged in carrying 

 vapour, is released as soon as that vapour is con- 

 densed and falls out of the air, being instantly felt 

 in the form of warmth. The air current passing 

 inland deprived of such moisture as it has lost by 

 condensation, is deprived also of the heat which 

 enabled it to bring that moisture to the coast ; whence 

 the far greater severity of winter at Leicester 

 and Perth compared with western localities corre- 

 sponding to these places in latitude, such as Limerick 

 and Oban. Dr. Haughton has calculated that, on 

 the west coast of Ireland as much heat is derived 

 from rainfall as from the direct action of the sun. 



In another important respect vegetation is 

 affected and its character modified by the amount 

 of vapour in the air. Moisture, in the invisible 

 form of vapour, interferes almost as much with the 

 passage of heat from the sun to the earth, and 

 with the radiation of heat from the earth into space, 

 as it does when partially condensed into the form 

 of mist or cloud. In proportion, therefore, as the 

 air current discharges itself of vapour by precipita- 

 tion in passing over the high grounds of our western 

 seaboard, is there less interference with the access 

 of sunrays to the surface of midland and eastern 

 districts. This secures for these districts brighter, 

 hotter summers than in the west ; subject always w 



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